Arimidex Drug Information
Generic name: ANASTROZOLE
Aromatase Inhibitor [EPC]
Uses of Arimidex
- is an aromatase inhibitor indicated for:
- Adjuvant treatment of postmenopausal women with hormone receptor-positive early breast cancer ( 1.1 )
- First-line treatment of postmenopausal women with hormone receptor-positive or hormone receptor-unknown locally advanced or metastatic breast cancer ( 1.2 )
- Treatment of advanced breast cancer in postmenopausal women with disease progression following tamoxifen therapy. Patients with ER-negative disease and patients who did not respond to previous tamoxifen therapy rarely responded to ARIMIDEX ( 1.3 ) 1.1 Adjuvant Treatment ARIMIDEX is indicated for adjuvant treatment of postmenopausal women with hormone receptor-positive early breast cancer. 1.2 First-Line Treatment ARIMIDEX is indicated for the first-line treatment of postmenopausal women with hormone receptor-positive or hormone receptor-unknown locally advanced or metastatic breast cancer. 1.3 Second-Line Treatment ARIMIDEX is indicated for the treatment of advanced breast cancer in postmenopausal women with disease progression following tamoxifen therapy. Patients with ER-negative disease and patients who did not respond to previous tamoxifen therapy rarely responded to ARIMIDEX.
Dosage & Administration of Arimidex
Recommended Dose
The dose of ARIMIDEX is one 1 mg tablet taken once a day. For patients with advanced breast cancer, ARIMIDEX should be continued until tumor progression. ARIMIDEX can be taken with or without food.
For adjuvant treatment of early breast cancer in postmenopausal women, the optimal duration of therapy is unknown. In the ATAC trial, ARIMIDEX was administered for five years . No dosage adjustment is necessary for patients with renal impairment or for elderly patients .
Patients with Hepatic Impairment No changes in dose are recommended for patients
with mild-to-moderate hepatic impairment. ARIMIDEX has not been studied in patients with severe hepatic impairment .
Side Effects of Arimidex
- Serious adverse reactions with ARIMIDEX occurring in less than 1 in 10,000 patients, are: 1) skin reactions such as lesions, ulcers, or blisters; 2) allergic reactions with swelling of the face, lips, tongue, and/or throat. This may cause difficulty in swallowing and/or breathing; and 3) changes in blood tests of the liver function, including inflammation of the liver with symptoms that may include a general feeling of not being well, with or without jaundice, liver pain or liver swelling [see Adverse Reactions ( 6.2 )] . Common adverse reactions (occurring with an incidence of ≥10%) in women taking ARIMIDEX included: hot flashes, asthenia, arthritis, pain, arthralgia, hypertension, depression, nausea and vomiting, rash, osteoporosis, fractures, back pain, insomnia, headache, bone pain, peripheral edema, increased cough, dyspnea, pharyngitis and lymphedema. In the ATAC trial, the most common reported adverse reaction (>0.1%) leading to discontinuation of therapy for both treatment groups was hot flashes, although there were fewer patients who discontinued therapy as a result of hot flashes in the ARIMIDEX group. Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. In the early breast cancer (ATAC) study, the most common (occurring with an incidence of ≥10%) side effects occurring in women taking ARIMIDEX included: hot flashes, asthenia, arthritis, pain, arthralgia, pharyngitis, hypertension, depression, nausea and vomiting, rash, osteoporosis, fractures, back pain, insomnia, headache, peripheral edema and lymphedema, regardless of causality. ( 6.1 ) In the advanced breast cancer studies, the most common (occurring with an incidence of >10%) side effects occurring in women taking ARIMIDEX included: hot flashes, nausea, asthenia, pain, headache, back pain, bone pain, increased cough, dyspnea, pharyngitis and peripheral edema. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact ANI Pharmaceuticals, Inc. at 1-855-204-1431 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch 6.1 Clinical Trials Experience Adjuvant Therapy Adverse reaction data for adjuvant therapy are based on the ATAC trial [see Clinical Studies ( 14.1 )] . The median duration of adjuvant treatment for safety evaluation was 59.8 months and 59.6 months for patients receiving ARIMIDEX 1 mg and tamoxifen 20 mg, respectively. Adverse reactions occurring with an incidence of at least 5% in either treatment group during treatment or within 14 days of the end of treatment are presented in Table 1. Table 1 - Adverse reactions occurring with an incidence of at least 5% in either treatment group during treatment, or within 14 days of the end of treatment in the ATAC trial The combination arm was discontinued due to lack of efficacy benefit at 33 months of follow-up. Body system and adverse reactions by COSTART preferred term COSTART Coding Symbols for Thesaurus of Adverse Reaction Terms. A patient may have had more than 1 adverse reaction, including more than 1 adverse reaction in the same body system. ARIMIDEX 1 mg (N N=Number of patients receiving the treatment. = 3092) Tamoxifen 20 mg (N = 3094) Body as a whole Asthenia 575 (19) 544 (18) Pain 533 (17) 485 (16) Back pain 321 (10) 309 (10) Headache 314 (10) 249 (8) Abdominal pain 271 (9) 276 (9) Infection 285 (9) 276 (9) Accidental injury 311 (10) 303 (10) Flu syndrome 175 (6) 195 (6) Chest pain 200 (7) 150 (5) Neoplasm 162 (5) 144 (5) Cyst 138 (5) 162 (5) Cardiovascular Vasodilatation 1104 (36) 1264 (41) Hypertension 402 (13) 349 (11) Digestive Nausea 343 (11) 335 (11) Constipation 249 (8) 252 (8) Diarrhea 265 (9) 216 (7) Dyspepsia 206 (7) 169 (6) Gastrointestinal disorder 210 (7) 158 (5) Hemic and lymphatic Lymphedema 304 (10) 341 (11) Anemia 113 (4) 159 (5) Metabolic and nutritional Peripheral edema 311 (10) 343 (11) Weight gain 285 (9) 274 (9) Hypercholesterolemia 278 (9) 108 (3.5) Musculoskeletal Arthritis 512 (17) 445 (14) Arthralgia 467 (15) 344 (11) Osteoporosis 325 (11) 226 (7) Fracture 315 (10) 209 (7) Bone pain 201 (7) 185 (6) Arthrosis 207 (7) 156 (5) Joint Disorder 184 (6) 160 (5) Myalgia 179 (6) 160 (5) Nervous system Depression 413 (13) 382 (12) Insomnia 309 (10) 281 (9) Dizziness 236 (8) 234 (8) Anxiety 195 (6) 180 (6) Paresthesia 215 (7) 145 (5) Respiratory Pharyngitis 443 (14) 422 (14) Cough increased 261 (8) 287 (9) Dyspnea 234 (8) 237 (8) Sinusitis 184 (6) 159 (5) Bronchitis 167 (5) 153 (5) Skin and appendages Rash 333 (11) 387 (13) Sweating 145 (5) 177 (6) Special Senses Cataract Specified 182 (6) 213 (7) Urogenital Leukorrhea 86 (3) 286 (9) Urinary tract infection 244 (8) 313 (10) Breast pain 251 (8) 169 (6) Breast Neoplasm 164 (5) 139 (5) Vulvovaginitis 194 (6) 150 (5) Vaginal Hemorrhage Vaginal Hemorrhage without further diagnosis. 122 (4) 180 (6) Vaginitis 125 (4) 158 (5) Certain adverse reactions and combinations of adverse reactions were prospectively specified for analysis, based on the known pharmacologic properties and side effect profiles of the two drugs (see Table 2). Table 2 - Number of Patients with Pre-specified Adverse Reactions in ATAC Trial Patients with multiple events in the same category are counted only once in that category. ARIMIDEX N=3092 (%) Tamoxifen N=3094 (%) Odds-ratio 95% CI Hot Flashes 1104 (36) 1264 (41) 0.80 0.73 − 0.89 Musculoskeletal Events Refers to joint symptoms, including joint disorder, arthritis, arthrosis and arthralgia. 1100 (36) 911 (29) 1.32 1.19 − 1.47 Fatigue/Asthenia 575 (19) 544 (18) 1.07 0.94 − 1.22 Mood Disturbances 597 (19) 554 (18) 1.10 0.97 − 1.25 Nausea and Vomiting 393 (13) 384 (12) 1.03 0.88 − 1.19 All Fractures 315 (10) 209 (7) 1.57 1.30 − 1.88 Fractures of Spine, Hip, or Wrist 133 (4) 91 (3) 1.48 1.13 − 1.95 Wrist/Colles’ fractures 67 (2) 50 (2) Spine fractures 43 (1) 22 (1) Hip fractures 28 (1) 26 (1) Cataracts 182 (6) 213 (7) 0.85 0.69 − 1.04 Vaginal Bleeding 167 (5) 317 (10) 0.50 0.41 − 0.61 Ischemic Cardiovascular Disease 127 (4) 104 (3) 1.23 0.95 − 1.60 Vaginal Discharge 109 (4) 408 (13) 0.24 0.19 − 0.30 Venous Thromboembolic Events 87 (3) 140 (5) 0.61 0.47 − 0.80 Deep Venous Thromboembolic Events 48 (2) 74 (2) 0.64 0.45 − 0.93 Ischemic Cerebrovascular Event 62 (2) 88 (3) 0.70 0.50 − 0.97 Endometrial Cancer Percentages calculated based upon the numbers of patients with an intact uterus at baseline. 4 (0.2) 13 (0.6) 0.31 0.10 − 0.94 Ischemic Cardiovascular Events Between treatment arms in the overall population of 6186 patients, there was no statistical difference in ischemic cardiovascular events (4% ARIMIDEX vs. 3% tamoxifen). In the overall population, angina pectoris was reported in 71/3092 (2.3%) patients in the ARIMIDEX arm and 51/3094 (1.6%) patients in the tamoxifen arm; myocardial infarction was reported in 37/3092 (1.2%) patients in the ARIMIDEX arm and 34/3094 (1.1%) patients in the tamoxifen arm. In women with pre-existing ischemic heart disease 465/6186 (7.5%), the incidence of ischemic cardiovascular events was 17% in patients on ARIMIDEX and 10% in patients on tamoxifen. In this patient population, angina pectoris was reported in 25/216 (11.6%) patients receiving ARIMIDEX and 13/249 (5.2%) patients receiving tamoxifen; myocardial infarction was reported in 2/216 (0.9%) patients receiving ARIMIDEX and 8/249 (3.2%) patients receiving tamoxifen. Bone Mineral Density Findings Results from the ATAC trial bone substudy at 12 and 24 months demonstrated that patients receiving ARIMIDEX had a mean decrease in both lumbar spine and total hip bone mineral density (BMD) compared to baseline. Patients receiving tamoxifen had a mean increase in both lumbar spine and total hip BMD compared to baseline. Because ARIMIDEX lowers circulating estrogen levels it may cause a reduction in bone mineral density. A post-marketing trial assessed the combined effects of ARIMIDEX and the bisphosphonate risedronate on changes from baseline in BMD and markers of bone resorption and formation in postmenopausal women with hormone receptor-positive early breast cancer. All patients received calcium and vitamin D supplementation. At 12 months, small reductions in lumbar spine bone mineral density were noted in patients not receiving bisphosphonates. Bisphosphonate treatment preserved bone density in most patients at risk of fracture. Postmenopausal women with early breast cancer scheduled to be treated with ARIMIDEX should have their bone status managed according to treatment guidelines already available for postmenopausal women at similar risk of fragility fracture. Cholesterol During the ATAC trial, more patients receiving ARIMIDEX were reported to have an elevated serum cholesterol compared to patients receiving tamoxifen (9% versus 3.5%, respectively). A post-marketing trial also evaluated any potential effects of ARIMIDEX on lipid profile. In the primary analysis population for lipids (ARIMIDEX alone), there was no clinically significant change in LDL-C from baseline to 12 months and HDL-C from baseline to 12 months. In secondary population for lipids (ARIMIDEX+risedronate), there also was no clinically significant change in LDL-C and HDL-C from baseline to 12 months. In both populations for lipids, there was no clinically significant difference in total cholesterol (TC) or serum triglycerides (TG) at 12 months compared with baseline. In this trial, treatment for 12 months with ARIMIDEX alone had a neutral effect on lipid profile. Combination treatment with ARIMIDEX and risedronate also had a neutral effect on lipid profile. The trial provides evidence that postmenopausal women with early breast cancer scheduled to be treated with ARIMIDEX should be managed using the current National Cholesterol Education Program guidelines for cardiovascular risk-based management of individual patients with LDL elevations. Other Adverse Reactions Patients receiving ARIMIDEX had an increase in joint disorders (including arthritis, arthrosis and arthralgia) compared with patients receiving tamoxifen. Patients receiving ARIMIDEX had an increase in the incidence of all fractures (specifically fractures of spine, hip and wrist) [315 (10%)] compared with patients receiving tamoxifen [209 (7%)]. Patients receiving ARIMIDEX had a higher incidence of carpal tunnel syndrome [78 (2.5%)] compared with patients receiving tamoxifen [22 (0.7%)]. Vaginal bleeding occurred more frequently in the tamoxifen-treated patients versus the ARIMIDEX-treated patients 317 (10%) versus 167 (5%), respectively. Patients receiving ARIMIDEX had a lower incidence of hot flashes, vaginal bleeding, vaginal discharge, endometrial cancer, venous thromboembolic events and ischemic cerebrovascular events compared with patients receiving tamoxifen. 10-year median follow-up Safety Results from the ATAC Trial Results are consistent with the previous analyses. Serious adverse reactions were similar between ARIMIDEX (50%) and tamoxifen (51%).
- Cardiovascular events were consistent with the known safety profiles of ARIMIDEX and tamoxifen.
- The cumulative incidences of all first fractures (both serious and non-serious, occurring either during or after treatment) was higher in the ARIMIDEX group (15%) compared to the tamoxifen group (11%). This increased first fracture rate during treatment did not continue in the post-treatment follow-up period.
- The cumulative incidence of new primary cancers was similar in the ARIMIDEX group (13.7%) compared to the tamoxifen group (13.9%). Consistent with the previous analyses, endometrial cancer was higher in the tamoxifen group (0.8%) compared to the ARIMIDEX group (0.2%).
- The overall number of deaths (during or off-trial treatment) was similar between the treatment groups. There were more deaths related to breast cancer in the tamoxifen than in the ARIMIDEX treatment group. First-Line Therapy Adverse reactions occurring with an incidence of at least 5% in either treatment group of trials 0030 and 0027 during or within 2 weeks of the end of treatment are shown in Table 3. Table 3 - Adverse Reactions Occurring with an Incidence of at Least 5% in Trials 0030 and 0027 Body system Adverse Reaction A patient may have had more than 1 adverse event. Number (%) of subjects ARIMIDEX (N=506) Tamoxifen (N=511) Whole body Asthenia 83 (16) 81 (16) Pain 70 (14) 73 (14) Back pain 60 (12) 68 (13) Headache 47 (9) 40 (8) Abdominal pain 40 (8) 38 (7) Chest pain 37 (7) 37 (7) Flu syndrome 35 (7) 30 (6) Pelvic pain 23 (5) 30 (6) Cardiovascular Vasodilation 128 (25) 106 (21) Hypertension 25 (5) 36 (7) Digestive Nausea 94 (19) 106 (21) Constipation 47 (9) 66 (13) Diarrhea 40 (8) 33 (6) Vomiting 38 (8) 36 (7) Anorexia 26 (5) 46 (9) Metabolic and Nutritional Peripheral edema 51 (10) 41 (8) Musculoskeletal Bone pain 54 (11) 52 (10) Nervous Dizziness 30 (6) 22 (4) Insomnia 30 (6) 38 (7) Depression 23 (5) 32 (6) Hypertonia 16 (3) 26 (5) Respiratory Cough increased 55 (11) 52 (10) Dyspnea 51 (10) 47 (9) Pharyngitis 49 (10) 68 (13) Skin and appendages Rash 38 (8) 34 (8) Urogenital Leukorrhea 9 (2) 31 (6) Less frequent adverse experiences reported in patients receiving ARIMIDEX 1 mg in either Trial 0030 or Trial 0027 were similar to those reported for second-line therapy. Based on results from second-line therapy and the established safety profile of tamoxifen, the incidences of 9 pre-specified adverse event categories potentially causally related to one or both of the therapies because of their pharmacology were statistically analyzed. No significant differences were seen between treatment groups. Table 4 - Number of Patients with Pre-specified Adverse Reactions in Trials 0030 and 0027 Adverse Reaction A patient may have had more than 1 adverse reaction. Number (n) and Percentage of Patients ARIMIDEX 1 mg (N=506) n (%) NOLVADEX 20 mg (N=511) n (%) Depression 23 (5) 32 (6) Tumor Flare 15 (3) 18 (4) Thromboembolic Disease Includes pulmonary embolus, thrombophlebitis, retinal vein thrombosis. 18 (4) 33 (6) Venous 5 15 Coronary and Cerebral Includes myocardial infarction, myocardial ischemia, angina pectoris, cerebrovascular accident, cerebral ischemia and cerebral infarct. 13 19 Gastrointestinal Disturbance 170 (34) 196 (38) Hot Flushes 134 (26) 118 (23) Vaginal Dryness 9 (2) 3 (1) Lethargy 6 (1) 15 (3) Vaginal Bleeding 5 (1) 11 (2) Weight Gain 11 (2) 8 (2) Second-Line Therapy ARIMIDEX was tolerated in two controlled clinical trials (i.e., Trials 0004 and 0005), with less than 3.3% of the ARIMIDEX-treated patients and 4.0% of the megestrol acetate-treated patients withdrawing due to an adverse reaction. The principal adverse reaction more common with ARIMIDEX than megestrol acetate was diarrhea. Adverse reactions reported in greater than 5% of the patients in any of the treatment groups in these two controlled clinical trials, regardless of causality, are presented below: Table 5 - Number (n) and Percentage of Patients with Adverse Reactions in Trials 0004 and 0005 Adverse Reaction A patient may have had more than one adverse reaction. ARIMIDEX ARIMIDEX Megestrol Acetate 1 mg 10 mg 160 mg (N=262) (N=246) (N=253) n % n % n % Asthenia 42 (16) 33 (13) 47 (19) Nausea 41 (16) 48 (20) 28 (11) Headache 34 (13) 44 (18) 24 (9) Hot Flashes 32 (12) 29 (11) 21 (8) Pain 28 (11) 38 (15) 29 (11) Back Pain 28 (11) 26 (11) 19 (8) Dyspnea 24 (9) 27 (11) 53 (21) Vomiting 24 (9) 26 (11) 16 (6) Cough Increased 22 (8) 18 (7) 19 (8) Diarrhea 22 (8) 18 (7) 7 (3) Constipation 18 (7) 18 (7) 21 (8) Abdominal Pain 18 (7) 14 (6) 18 (7) Anorexia 18 (7) 19 (8) 11 (4) Bone Pain 17 (6) 26 (12) 19 (8) Pharyngitis 16 (6) 23 (9) 15 (6) Dizziness 16 (6) 12 (5) 15 (6) Rash 15 (6) 15 (6) 19 (8) Dry Mouth 15 (6) 11 (4) 13 (5) Peripheral Edema 14 (5) 21 (9) 28 (11) Pelvic Pain 14 (5) 17 (7) 13 (5) Depression 14 (5) 6 (2) 5 (2) Chest Pain 13 (5) 18 (7) 13 (5) Paresthesia 12 (5) 15 (6) 9 (4) Vaginal Hemorrhage 6 (2) 4 (2) 13 (5) Weight Gain 4 (2) 9 (4) 30 (12) Sweating 4 (2) 3 (1) 16 (6) Increased Appetite 0 (0) 1 (0) 13 (5) Other less frequent (2% to 5%) adverse reactions reported in patients receiving ARIMIDEX 1 mg in either Trial 0004 or Trial 0005 are listed below. These adverse experiences are listed by body system and are in order of decreasing frequency within each body system regardless of assessed causality. Body as a Whole: Flu syndrome; fever; neck pain; malaise; accidental injury; infection Cardiovascular: Hypertension; thrombophlebitis Hepatic: Gamma GT increased; SGOT increased; SGPT increased Hematologic: Anemia; leukopenia Metabolic and Nutritional: Alkaline phosphatase increased; weight loss Mean serum total cholesterol levels increased by 0.5 mmol/L among patients receiving ARIMIDEX. Increases in LDL cholesterol have been shown to contribute to these changes. Musculoskeletal: Myalgia; arthralgia; pathological fracture Nervous: Somnolence; confusion; insomnia; anxiety; nervousness Respiratory: Sinusitis; bronchitis; rhinitis Skin and Appendages: Hair thinning (alopecia); pruritus Urogenital: Urinary tract infection; breast pain The incidences of the following adverse reaction groups potentially causally related to one or both of the therapies because of their pharmacology, were statistically analyzed: weight gain, edema, thromboembolic disease, gastrointestinal disturbance, hot flushes, and vaginal dryness. These six groups, and the adverse reactions captured in the groups, were prospectively defined. The results are shown in the table below. Table 6 - Number (n) and Percentage of Patients with Pre-specified Adverse Reactions in Trials 0004 and 0005 Adverse Reaction Group ARIMIDEX ARIMIDEX Megestrol Acetate 1 mg 10 mg 160 mg (N=262) (N=246) (N=253) n (%) n (%) n (%) Gastrointestinal Disturbance 77 (29) 81 (33) 54 (21) Hot Flushes 33 (13) 29 (12) 35 (14) Edema 19 (7) 28 (11) 35 (14) Thromboembolic Disease 9 (3) 4 (2) 12 (5) Vaginal Dryness 5 (2) 3 (1) 2 (1) Weight Gain 4 (2) 10 (4) 30 (12) 6.2 Post-Marketing Experience These adverse reactions are reported voluntarily from a population of uncertain size. Therefore, it is not always possible to estimate reliably their frequency or establish a causal relationship to drug exposure. The following have been reported in post-approval use of ARIMIDEX:
- Hepatobiliary events including increases in alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, gamma-GT, and bilirubin; hepatitis
- Rash including cases of mucocutaneous disorders such as erythema multiforme and Stevens-Johnson syndrome
- Cases of allergic reactions including angioedema, urticaria and anaphylaxis [see Contraindications ( 4 )]
- Myalgia and hypercalcemia (with or without an increase in parathyroid hormone)
- Tendon disorders including tendon rupture, tendonitis, tenosynovitis, and tenosynovitis stenosans (trigger finger)
Warnings & Cautions for Arimidex
- In women with pre-existing ischemic heart disease, an increased incidence of ischemic cardiovascular events occurred with ARIMIDEX use compared to tamoxifen use. Consider risks and benefits. ( 5.1 , 6.1 )
- Decreases in bone mineral density may occur. Consider bone mineral density monitoring. ( 5.2 , 6.1 )
- Increases in total cholesterol may occur. Consider cholesterol monitoring. ( 5.3 , 6.1 )
- Embryo-Fetal Toxicity: ARIMIDEX may cause fetal harm. Advise patients of the potential risk to a fetus and to use effective contraception. ( 5.4 , 8.1 ) 5.1 Ischemic Cardiovascular Events In women with pre-existing ischemic heart disease, an increased incidence of ischemic cardiovascular events was observed with ARIMIDEX in the ATAC trial (17% of patients on ARIMIDEX and 10% of patients on tamoxifen). Consider risk and benefits of ARIMIDEX therapy in patients with pre-existing ischemic heart disease [see Adverse Reactions ( 6.1 )] . 5.2 Bone Effects Results from the ATAC trial bone substudy at 12 and 24 months demonstrated that patients receiving ARIMIDEX had a mean decrease in both lumbar spine and total hip bone mineral density (BMD) compared to baseline. Patients receiving tamoxifen had a mean increase in both lumbar spine and total hip BMD compared to baseline. Consider bone mineral density monitoring in patients treated with ARIMIDEX [see Adverse Reactions ( 6.1 )] . 5.3 Cholesterol During the ATAC trial, more patients receiving ARIMIDEX were reported to have elevated serum cholesterol compared to patients receiving tamoxifen (9% versus 3.5%, respectively) [see Adverse Reactions ( 6.1 )] . 5.4 Embryo-Fetal Toxicity Based on findings from animal studies and its mechanism of action, ARIMIDEX can cause fetal harm when administered to a pregnant woman. Anastrozole caused embryo-fetal toxicities in rats at maternal exposure that were 9 times the human clinical exposure, based on area under the curve (AUC). In rabbits, anastrozole caused pregnancy failure at doses equal to or greater than 16 times the recommended human dose on a mg/m 2 basis. Advise pregnant women and females of reproductive potential of the potential risk to a fetus. Advise females of reproductive potential to use effective contraception during therapy with ARIMIDEX and for at least 3 weeks after the last dose [see Use in Specific Populations ( 8.1 , 8.3 ) and Clinical Pharmacology ( 12.1 )] .
Drug Interactions with Arimidex
- Tamoxifen: Do not use in combination with ARIMIDEX. No additional benefit seen over tamoxifen monotherapy. ( 7.1 , 14.1 )
- Estrogen-containing products: Combination use may diminish activity of ARIMIDEX. ( 7.2 ) 7.1 Tamoxifen Co-administration of anastrozole and tamoxifen in breast cancer patients reduced anastrozole plasma concentration by 27%. However, the co-administration of anastrozole and tamoxifen did not affect the pharmacokinetics of tamoxifen or N-desmethyltamoxifen. At a median follow-up of 33 months, the combination of ARIMIDEX and tamoxifen did not demonstrate any efficacy benefit when compared with tamoxifen in all patients as well as in the hormone receptor-positive subpopulation. This treatment arm was discontinued from the trial [see Clinical Studies ( 14.1 )] . Based on clinical and pharmacokinetic results from the ATAC trial, tamoxifen should not be administered with anastrozole. 7.2 Estrogen Estrogen-containing therapies should not be used with ARIMIDEX as they may diminish its pharmacological action. 7.3 Warfarin In a study conducted in 16 male volunteers, anastrozole did not alter the exposure (as measured by C max and AUC) and anticoagulant activity (as measured by prothrombin time, activated partial thromboplastin time, and thrombin time) of both R- and S-warfarin. 7.4 Cytochrome P450 Based on in vitro and in vivo results, it is unlikely that co-administration of ARIMIDEX 1 mg will affect other drugs as a result of inhibition of cytochrome P450 [see Clinical Pharmacology ( 12.3 )] .
Pregnancy Safety for Arimidex
Pregnancy Risk Summary Based on findings from animal studies and its mechanism of action, ARIMIDEX may cause fetal harm when administered to a pregnant woman . There are no studies of ARIMIDEX use in pregnant women. Anastrozole caused embryo-fetal toxicities in rats at maternal exposure that were 9 times the human clinical exposure, based on area under the curve (AUC). In rabbits, anastrozole caused pregnancy failure at doses equal to or greater than 16 times the recommended human dose on a mg/m 2 basis. Advise pregnant women and females of reproductive potential of the potential risk to a fetus.
The background risk of major birth defects and miscarriage for the indicated population is unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively. Data Animal Data In animal reproduction studies, pregnant rats and rabbits received anastrozole during organogenesis at doses equal to or greater than 0.1 and 0.02 mg/kg/day, respectively, (about 1 and 1/3 the recommended human dose on a mg/m 2 basis, respectively). In both species, anastrozole crossed the placenta, and there was increased pregnancy loss (increased pre- and/or post-implantation loss, increased resorption, and decreased numbers of live fetuses). In rats, these effects were dose related, and placental weights were significantly increased at doses equal to or greater than 0.1 mg/kg/day.
Fetotoxicity, including delayed fetal development (i.e., incomplete ossification and depressed fetal body weights), occurred in rats at anastrozole doses of 1 mg/kg/day that produced peak plasma levels 19 times higher than serum levels in humans at the therapeutic dose (AUC 0-24hr 9 times higher). In rabbits, anastrozole caused pregnancy failure at doses equal to or greater than 1.0 mg/kg/day (about 16 times the recommended human dose on a mg/m 2 basis).
Pediatric Use of Arimidex
L (50.7-330.0 L).
The terminal elimination half-life was 46.8 h, which was similar to that observed in postmenopausal women treated with anastrozole for breast cancer. Based on a population pharmacokinetic analysis, the pharmacokinetics of anastrozole was similar in boys with pubertal gynecomastia and girls with McCune-Albright Syndrome.
Contraindications for Arimidex
Hypersensitivity ARIMIDEX is contraindicated in any patient who has shown a hypersensitivity reaction to the drug or to any of the excipients. Observed reactions include anaphylaxis, angioedema, and urticaria . Patients with demonstrated hypersensitivity to ARIMIDEX or any excipient
Overdosage Information for Arimidex
Clinical trials have been conducted with ARIMIDEX, up to 60 mg in a single dose given to healthy male volunteers and up to 10 mg daily given to postmenopausal women with advanced breast cancer; these dosages were tolerated. A single dose of ARIMIDEX that results in life-threatening symptoms has not been established. There is no specific antidote to overdosage and treatment must be symptomatic.
In the management of an overdose, consider that multiple agents may have been taken. Vomiting may be induced if the patient is alert. Dialysis may be helpful because ARIMIDEX is not highly protein bound.
General supportive care, including frequent monitoring of vital signs and close observation of the patient, is indicated.
Clinical Studies of Arimidex
Adjuvant Treatment of Breast Cancer in Postmenopausal Women
A multicenter, double-blind trial (ATAC) randomized 9,366 postmenopausal women with operable breast cancer to adjuvant treatment with ARIMIDEX 1 mg daily, tamoxifen 20 mg daily, or a combination of the two treatments for five years or until recurrence of the disease. The primary endpoint of the trial was disease-free survival (i.e., time to occurrence of a distant or local recurrence, or contralateral breast cancer or death from any cause). Secondary endpoints of the trial included distant disease-free survival, the incidence of contralateral breast cancer and overall survival. At a median follow-up of 33 months, the combination of ARIMIDEX and tamoxifen did not demonstrate any efficacy benefit when compared with tamoxifen in all patients as well as in the hormone receptor positive subpopulation.
This treatment arm was discontinued from the trial. Based on clinical and pharmacokinetic results from the ATAC trial, tamoxifen should not be administered with anastrozole . Demographic and other baseline characteristics were similar among the three treatment groups (see Table 7). Table 7 - Demographic and Baseline Characteristics for ATAC Trial Demographic Characteristic ARIMIDEX 1 mg (N N=Number of patients randomized to the treatment =3125) Tamoxifen 20 mg (N =3116) ARIMIDEX 1 mg plus Tamoxifen The combination arm was discontinued due to lack of efficacy benefit at 33 months of follow-up 20 mg (N =3125) Mean age (yrs.) 64.1 64.1
Age Range (yrs.) 38.1 - 92.8 32.8 - 94.9 37.0 - 92.2
Age Distribution (%) <45 yrs. 0.7 0.4 0.5 45-60 yrs. 34.6 35.0 34.5 >60 <70 yrs. 38.0 37.1 37.7 >70 yrs. 26.7 27.4
Mean Weight (kg) 70.8 71.1 71.3 Receptor Status (%) Positive Includes patients
who were estrogen receptor (ER) positive or progesterone receptor (PgR) positive, or both positive 83.5 83.1
Negative Includes patients with both ER negative and PgR negative receptor status
7.4 8.0
Other Includes all other combinations of ER and PgR receptor status unknown
8.8 8.6
Other Treatment (%) prior to Randomization Mastectomy 47.8 47.3 48.1 Breast conservation
Among the patients who had breast conservation, radiotherapy was administered to 95.0% of patients in the ARIMIDEX arm, 94.1% in the tamoxifen arm and 94.5% in the ARIMIDEX plus tamoxifen arm. 52.3 52.8
Neoadjuvant Tamoxifen 1.6 1.6 1.7 Primary Tumor Size (%) T1 (≤2 cm)
63.9 62.9
T2 (>2 cm and ≤5 cm) 32.6 34.2 32.9 T3 (>5 cm)
2.7 2.2
Nodal Status (%) Node positive 34.9 33.6 33.5 1-3 (# of nodes)
24.4 24.4 24.3 4-9 7.5 6.4 6.8 >9 2.9 2.7
Tumor Grade (%) Well-differentiated 20.8 20.5 21.2 Moderately differentiated 46.8 47.8 46.5
Poorly/undifferentiated 23.7 23.3
Not assessed/recorded 8.7 8.4 8.5 Patients in the two monotherapy arms of
the ATAC trial were treated for a median of 60 months (5 years) and followed for a median of 68 months. Disease-free survival in the intent-to-treat population was statistically significantly improved in the ARIMIDEX arm compared to the tamoxifen arm. In the hormone receptor-positive subpopulation representing about 84% of the trial patients, disease-free survival was also statistically significantly improved (HR = 0.83, 95% CI: 0.73, 0.94, p=0.0049) in the ARIMIDEX arm compared to the tamoxifen arm.
Figure 1 - Disease-Free Survival Kaplan Meier Survival Curve for all Patients Randomized to ARIMIDEX or Tamoxifen Monotherapy in the ATAC Trial (Intent-to-Treat) Figure 2 - Disease-Free Survival for Hormone Receptor-Positive Subpopulation of Patients Randomized to ARIMIDEX or Tamoxifen Monotherapy in the ATAC Trial The survival data with 68 months follow-up is presented in Table 9. In the group of patients who had previous adjuvant chemotherapy (N=698 for ARIMIDEX and N=647 for tamoxifen), the hazard ratio for disease-free survival was 0.91 (95% CI: 0.73 to 1.13) in the ARIMIDEX arm compared to the tamoxifen arm. The frequency of individual events in the intent-to-treat population and the hormone receptor-positive subpopulation are described in Table 8. Table 8 - All Recurrence and Death Events The combination arm was discontinued due to lack of efficacy benefit at 33 months of follow-up. Intent-To-Treat Population Patients may fall into more than one category.
Hormone Receptor-Positive Subpopulation ARIMIDEX 1 mg (N N=Number of patients randomized. =3125) Tamoxifen 20 mg (N =3116) ARIMIDEX 1 mg (N =2618) Tamoxifen 20 mg (N =2598) Median Duration of Therapy (mo) 60 60 60 60 Median Efficacy Follow-up (mo) 68 68 68 68 Loco-regional recurrence 119 149 76 101 Contralateral breast cancer 35 59 26 54 Invasive 27 52 21 48 Ductal carcinoma in situ 8 6 5 5 Unknown 0 1 (<0.1) 0 1 (<0.1) Distant recurrence 324 375 226 265 Death from Any Cause 411 420 296 301 Death breast cancer 218 248 138 160 Death other reason (including unknown) 193 172 158 141 A summary of the study efficacy results is provided in Table 9. Table 9 - ATAC Efficacy Summary The combination arm was discontinued due to lack of efficacy benefit at 33 months of follow-up. Intent-To-Treat Population Hormone Receptor-Positive Subpopulation ARIMIDEX 1 mg (N=3125) Tamoxifen 20 mg (N=3116) ARIMIDEX 1 mg (N=2618) Tamoxifen 20 mg (N=2598) Number of Events Number of Events Disease-free Survival 575 651 424 497 Hazard ratio 0.87 0.83 2-sided 95% CI 0.78 to 0.97 0.73 to 0.94 p-value 0.0127 0.0049 Distant Disease-free Survival 500 530 370 394 Hazard ratio 0.94 0.93 2-sided 95% CI 0.83 to 1.06 0.80 to 1.07 Overall Survival 411 420 296 301 Hazard ratio 0.97 0.97 2-sided 95% CI 0.85 to 1.12 0.83 to 1.14 10-year median follow-up Efficacy Results from the ATAC Trial In a subsequent analysis of the ATAC trial, patients in the two monotherapy arms were followed for a median of 120 months (10 years). Patients received study treatment for a median of 60 months (5 years) (see Table 10). Table 10 - Efficacy Summary Intent-To-Treat Population Hormone Receptor-Positive Subpopulation ARIMIDEX 1 mg (N=3125) Tamoxifen 20 mg (N=3116) ARIMIDEX 1 mg (N=2618) Tamoxifen 20 mg (N=2598) Number of Events Number of Events Disease-free Survival 953 1022 735 924 Hazard ratio 0.91 0.86 2-sided 95% CI 0.83 to 0.99 0.78 to 0.95 p-value 0.0365 0.0027 Overall Survival 734 747 563 586 Hazard ratio 0.97 0.95 2-sided 95% CI 0.88 to 1.08 0.84 to 1.06 Figure 3 - Disease-Free Survival Kaplan Meier Survival Curve for all Patients Randomized to ARIMIDEX or Tamoxifen Monotherapy in the ATAC Trial (Intent-to-Treat) (a) a The proportion of patients with 120 months’ follow-up was 29.4%. Figure 4 - Disease-Free Survival for Hormone Receptor-Positive Subpopulation of Patients Randomized to ARIMIDEX or Tamoxifen Monotherapy in the ATAC Trial (b) b The proportion of patients with 120 months’ follow-up was 29.8%. Figure-1 Figure-2 figure 3 figure 4
First-Line Therapy in Postmenopausal Women with Advanced Breast Cancer Two double-blind, controlled
clinical studies of similar design (0030, a North American study and 0027, a predominately European study) were conducted to assess the efficacy of ARIMIDEX compared with tamoxifen as first-line therapy for hormone receptor positive or hormone receptor unknown locally advanced or metastatic breast cancer in postmenopausal women. A total of 1021 patients between the ages of 30 and 92 years old were randomized to receive trial treatment. Patients were randomized to receive 1 mg of ARIMIDEX once daily or 20 mg of tamoxifen once daily.
The primary endpoints for both trials were time to tumor progression, objective tumor response rate, and safety. Demographics and other baseline characteristics, including patients who had measurable and no measurable disease, patients who were given previous adjuvant therapy, the site of metastatic disease and ethnic origin were similar for the two treatment groups for both trials. The following table summarizes the hormone receptor status at entry for all randomized patients in trials 0030 and 0027. Table 11 - Demographic and Other Baseline Characteristics Number (%) of subjects Trial 0030 Trial 0027 Receptor status ARIMIDEX 1 mg (N=171) Tamoxifen 20 mg (N=182) ARIMIDEX 1 mg (N=340) Tamoxifen 20 mg (N=328) ER ER=Estrogen receptor and/or PgR PgR=Progesterone receptor 151 162 154 144 ER unknown, PgR unknown 19 20 185 183 For the primary endpoints, trial 0030 showed that ARIMIDEX had a statistically significant advantage over tamoxifen (p=0.006) for time to tumor progression; objective tumor response rates were similar for ARIMIDEX and tamoxifen.
Trial 0027 showed that ARIMIDEX and tamoxifen had similar objective tumor response rates and time to tumor progression (see Table 12 and Figures 5 and 6). Table 12 below summarizes the results of trial 0030 and trial 0027 for the primary efficacy endpoints. Table 12 - Efficacy Results of First-line Treatment Endpoint Trial 0030 Trial 0027 ARIMIDEX 1 mg (N=171) Tamoxifen 20 mg (N=182) ARIMIDEX 1 mg (N=340) Tamoxifen 20 mg (N=328) Time to progression (TTP) Median TTP (months) 11.1 5.6 8.2
Number (%) of subjects who progressed 114 (67%) 138 (76%) 249 (73%)
247 (75%) Hazard ratio (LCL LCL=Lower Confidence Limit ) Tamoxifen:ARIMIDEX 1.42 1.01 2-sided 95% CI CI=Confidence Interval p-value Two-sided Log Rank 0.006 0.920 Best objective response rate Number (%) of subjects with CR CR=Complete Response + PR PR=Partial Response 36 (21.1%) 31 (17.0%) 112 (32.9%) 107 (32.6%) Odds Ratio (LCL ) ARIMIDEX:Tamoxifen 1.30 1.01 Figure 5 - Kaplan-Meier probability of time to disease progression for all randomized patients (intent-to-treat) in Trial 0030 Figure 6 - Kaplan-Meier probability of time to progression for all randomized patients (intent-to-treat) in Trial 0027 Results from the secondary endpoints were supportive of the results of the primary efficacy endpoints. There were too few deaths occurring across treatment groups of both trials to draw conclusions on overall survival differences. figure 5 figure 6
Second-Line Therapy in Postmenopausal Women with Advanced Breast Cancer who had Disease
Progression following Tamoxifen Therapy Anastrozole was studied in two controlled clinical trials (0004, a North American study; 0005, a predominately European study) in postmenopausal women with advanced breast cancer who had disease progression following tamoxifen therapy for either advanced or early breast cancer. Some of the patients had also received previous cytotoxic treatment. Most patients were ER-positive; a smaller fraction were ER-unknown or ER-negative; the ER-negative patients were eligible only if they had a positive response to tamoxifen.
Eligible patients with measurable and non-measurable disease were randomized to receive either a single daily dose of 1 mg or 10 mg of ARIMIDEX or megestrol acetate 40 mg four times a day. The studies were double-blinded with respect to ARIMIDEX. Time to progression and objective response (only patients with measurable disease could be considered partial responders) rates were the primary efficacy variables. Objective response rates were calculated based on the Union Internationale Contre le Cancer (UICC) criteria.
The rate of prolonged (more than 24 weeks) stable disease, the rate of progression, and survival were also calculated. Both trials included over 375 patients; demographics and other baseline characteristics were similar for the three treatment groups in each trial. Patients in the 0005 trial had responded better to prior tamoxifen treatment.
Of the patients entered who had prior tamoxifen therapy for advanced disease (58% in Trial 0004; 57% in Trial 0005), 18% of these patients in Trial 0004 and 42% in Trial 0005 were reported by the primary investigator to have responded. In Trial 0004, 81% of patients were ER-positive, 13% were ER-unknown, and 6% were ER-negative. In Trial 0005, 58% of patients were ER-positive, 37% were ER-unknown, and 5% were ER-negative.
In Trial 0004, 62% of patients had measurable disease compared to 79% in Trial 0005. The sites of metastatic disease were similar among treatment groups for each trial. On average, 40% of the patients had soft tissue metastases; 60% had bone metastases; and 40% had visceral (15% liver) metastases. Efficacy results from the two studies were similar as presented in Table 13. In both studies there were no significant differences between treatment arms with respect to any of the efficacy parameters listed in the table below.
Table 13 - Efficacy Results of Second-line Treatment ARIMIDEX 1 mg ARIMIDEX 10 mg Megestrol Acetate 160 mg Trial 0004 ( N. America ) (N=128) (N=130) (N=128) Median Follow-up (months) Surviving Patients 31.3 30.9
Median Time to Death (months) 29.6 25.7 26.7 2 Year Survival Probability
(%) 62.0 58.0
Median Time to Progression (months) 5.7 5.3 5.1 Objective Response (all patients)
(%) 12.5 10.0
Stable Disease for >24 weeks (%) 35.2 29.2 32.8 Progression (%) 86.7
85.4
Trial 0005 ( Europe, Australia, S. Africa ) (N=135) (N=118) (N=125) Median
Follow-up (months) 31.0 30.9
Median Time to Death (months) 24.3 24.8 19.8 2 Year Survival Probability
(%) 50.5 50.9
Median Time to Progression (months) 4.4 5.3 3.9 Objective Response (all patients)
(%) 12.6 15.3
Stable Disease for >24 weeks (%) 24.4 25.4 23.2 Progression (%) 91.9
89.8
When data from the two controlled trials are pooled, the objective response
rates and median times to progression and death were similar for patients randomized to ARIMIDEX 1 mg and megestrol acetate. There is, in this data, no indication that ARIMIDEX 10 mg is superior to ARIMIDEX 1 mg. Table 14 - Pooled Efficacy Results of Second-line Treatment Trials 0004 & 0005 (Pooled Data) ARIMIDEX 1 mg N=263 ARIMIDEX 10 mg N=248 Megestrol Acetate 160 mg N=253 Median Time to Death (months) 26.7 25.5 22.5 2 Year Survival Probability (%) 56.1 54.6
Median Time to Progression 4.8 5.3 4.6 Objective Response (all patients) (%)
12.5 12.5 12.3
Drug information sourced from the FDA. This content is for informational purposes only and does not constitute medical advice. Consult a healthcare professional before making any medication decisions.
Ready to save on Arimidex?
Compare prescription prices at over 70,000 pharmacies and start saving today—no enrollment required.
Compare Arimidex Prices