Bethkis Drug Information
Generic name: TOBRAMYCIN
Aminoglycoside Antibacterial [EPC]
Uses of Bethkis
is indicated for the management of cystic fibrosis patients with Pseudomonas aeruginosa. Safety and efficacy have not been demonstrated in patients under the age of six years, patients with FEV 1 less than 40% or greater than 80% predicted, or patients colonized with Burkholderia cepacia . BETHKIS is an inhaled aminoglycoside antibacterial indicated for the management of cystic fibrosis patients with Pseudomonas aeruginosa. Safety and efficacy have not been demonstrated in patients under the age of six years, patients with a forced expiratory volume in one second (FEV 1 ) less than 40% or greater than 80% predicted, or patients colonized with Burkholderia cepacia.
Dosage & Administration of Bethkis
Dosage Bethkis is for oral inhalation only .
The recommended dosage of BETHKIS for patients six years of age and older is to administer one single-use ampule (300 mg/4 mL) twice daily by oral inhalation in repeated cycles of 28 days on drug, followed by 28 days off drug. The doses should be taken as close to 12 hours apart as possible and not less than 6 hours apart. The 300 mg/4 mL dose of BETHKIS is the same for patients regardless of age or weight.
BETHKIS has not been studied in patients less than six years old. If patients miss a dose, they should take it as soon as possible anytime up to 6 hours prior to their next scheduled dose. If less than 6 hours remain before the next dose, wait until their next scheduled dose.
Administration Instructions
BETHKIS is administered by oral inhalation using a hand-held PARI LC PLUS Reusable Nebulizer with a PARI Vios Air compressor over an approximately 15 minute period and until sputtering from the output of the nebulizer has occurred for at least one minute. BETHKIS should not be diluted or mixed with dornase alfa or other medications in the nebulizer. BETHKIS is not for subcutaneous, intravenous, or intrathecal administration.
Further patient instructions on how to administer BETHKIS are provided in the Patient’s Instructions for Use. BETHKIS should not be used if it is cloudy, if there are particles in the solution, or if it has been stored at room temperature for more than 28 days.
Side Effects of Bethkis
Clinical Trials Experience
Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in clinical trials of drugs cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. The data described below reflect exposure to BETHKIS in two placebo-controlled studies in 305 cystic fibrosis patients. Patients receiving BETHKIS ranged in age from 6 to 31 years.
In Study 1, an eight week study, 29 patients received BETHKIS versus 30 patients who received placebo for a total of four weeks on drug and four weeks off drug. All patients were ≤ 30 years of age (mean age 12.6 years) and 46% were females. 52.5% of patients were 6 to 12 years of age while 30.5% of patients were 13-17 years old. Only 16.5% of patients were adults (> 17 years old). Eighty percent (80%) of patients were chronically colonized with Pseudomonas aeruginosa while 20.3% of patients were initially or intermittently colonized with Pseudomonas aeruginosa during the study.
More patients in the placebo group discontinued/dropped out of Study 1 than in the BETHKIS group (23% vs 3.4%, respectively). Five patients in the placebo group compared to none in the BETHKIS group discontinued/dropped out because of treatment-emergent adverse events (TEAEs) such as pulmonary exacerbations and respiratory disorders. In Study 2, a 24 week study, 161 patients received BETHKIS versus 85 patients who received placebo in alternating four week on-off cycles for three cycles. All patients were ≤ 46 years of age (mean age 14.8 years) and 45% were females. 41% of patients were 6-12 years old while 29% of patients were 13-17 years old.
Only 30% were adults (>17 years). Eighty-seven percent (87%) of patients were chronically colonized with P. aeruginosa. Only 13% were either initially or intermittently colonized with P. aeruginosa during the study. More patients in the placebo group discontinued/dropped out of Study 2 than in the BETHKIS group (9.4% vs 4.3%, respectively). Of these, 3 patients in the BETHKIS group (1.9%) compared to 2 patients in the placebo group (2.4%) withdrew due to a TEAE. The most common TEAEs causing patients to discontinue from the study drug are respiratory, thoracic, and mediastinal disorders.
The most common adverse experiences reported were respiratory disorders, consistent with the underlying disease in the patient population being evaluated and these were similarly distributed between both BETHKIS- and placebo-treated patients. The following adverse reactions were reported in at least 5% of Bethkis-treated patients and at rates ≥ 2% more common compared to the placebo-treated patients: decreased forced expiratory volume, rales, red blood cell sedimentation rate increased, and dysphonia (Table 1). Table 1: Patients with Selected Treatment-Emergent Adverse Reactions Occurring in ≥ 2% of BETHKIS Patients Adverse Reactions BETHKIS N=190 (%) Placebo N=115 (%) Forced expiratory volume decreased 59 (31%) 33 (29%) Rales 36 (19%) 18 (16%) Red blood cell sedimentation rate increased 16 (8%) 6 (5%) Dysphonia 11 (6%) 2 (2%) Wheezing 10 (5%) 4 (4%) Epistaxis 6 (3%) 0 Pharyngolaryngeal pain 5 (3%) 2 (2%) Bronchitis 5 (3%) 1 (1%) Tonsillitis 4 (2%) 0 Diarrhea 3 (2%) 1 (1%) Eosinophilia 3 (2%) 0 Immunoglobulins increased 3 (2%) 0
Postmarketing Experience
The following adverse reactions have been identified during postapproval use of tobramycin inhalation solution. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Ear and labyrinth disorders: Hearing loss, Tinnitus Skin and subcutaneous tissue disorders : Hypersensitivity, pruritus, urticaria, rash Nervous system disorders : Aphonia, dysgeusia Respiratory, thoracic, and mediastinal disorders: Bronchospasm , oropharyngeal pain Metabolism and Nutrition Disorders: Decreased appetite
Warnings & Cautions for Bethkis
Ototoxicity Ototoxicity with use of
BETHKIS Caution should be exercised when prescribing BETHKIS to patients with known or suspected auditory or vestibular dysfunction. Findings related to ototoxicity as measured by audiometric evaluations and auditory adverse event reports were similar between BETHKIS and placebo in controlled clinical trials. Hearing loss was reported in two (1.1%) BETHKIS-treated patients and in one (0.9%) placebo-treated patient during clinical studies.
Additionally, dizziness and vertigo, both of which may be manifestations of vestibular forms of ototoxicity, were observed in similar numbers of BETHKIS- and placebo-treated patients. Dizziness occurred in two (1.1%) BETHKIS-treated patients and one (0.9%) placebo-treated patient and vertigo occurred in two (1.1%) BETHKIS-treated patients versus no placebo patients in clinical studies. None of the BETHKIS patients discontinued their therapy due to hearing loss, dizziness or vertigo.
Tinnitus may be a sentinel symptom of ototoxicity. No reports of tinnitus occurred in patients during clinical studies with BETHKIS, but because it has been observed with inhaled tobramycin solutions , onset of this symptom warrants caution. Ototoxicity, manifested as both auditory and vestibular toxicity, has been reported with parenteral aminoglycosides.
Vestibular toxicity may be manifested by vertigo, ataxia or dizziness. Patients with known or suspected auditory or vestibular dysfunction should be closely monitored when taking BETHKIS. Monitoring may include obtaining audiometric evaluations and serum tobramycin levels. If ototoxicity is noted, the patient should be managed as medically appropriate, including potentially discontinuing BETHKIS. Risk of Ototoxicity Due to Mitochondrial DNA Variants Cases of ototoxicity with aminoglycosides have been observed in patients with certain variants in the mitochondrially encoded 12S rRNA gene (MT-RNR1), particularly the m.1555A>G variant.
Ototoxicity occurred in some patients even when their aminoglycoside serum levels were within the recommended range. Mitochondrial DNA variants are present in less than 1% of the general US population, and the proportion of the variant carriers who may develop ototoxicity as well as the severity of ototoxicity is unknown. In case of known maternal history of ototoxicity due to aminoglycoside use or a known mitochondrial DNA variant in the patient, consider alternative treatments other than aminoglycosides unless the increased risk of permanent hearing loss is outweighed by the severity of infection and lack of safe and effective alternative therapies.
Nephrotoxicity Caution should be exercised when prescribing
BETHKIS to patients with known or suspected renal dysfunction. Nephrotoxicity was not seen during BETHKIS clinical studies but has been associated with aminoglycosides as a class. Patients with known or suspected renal dysfunction or taking concomitant nephrotoxic drugs along with BETHKIS should have serum concentrations of tobramycin and laboratory measurements of renal function obtained at the discretion of the treating physician.
If nephrotoxicity develops, the patient should be managed as medically appropriate, including potentially discontinuing BETHKIS until serum concentrations fall below 2 mcg/mL. Twenty-six (14%) BETHKIS patients and 15 (13%) placebo patients had increases in serum creatinine of at least 50% over baseline. Follow-up values were obtained for 17 of the 26 BETHKIS patients, all of which decreased to serum creatinine values that were within normal laboratory ranges. Patients who experience an increase in serum creatinine during treatment with BETHKIS should have their renal function closely monitored.
Neuromuscular Disorders
BETHKIS should be used cautiously in patients with muscular disorders. Aminoglycosides, including tobramycin, may aggravate muscle weakness because of a potential curare-like effect on neuromuscular function. Neuromuscular blockade, respiratory failure, and prolonged respiratory paralysis may occur more commonly in patients with underlying neuromuscular disorders, such as myasthenia gravis or Parkinson’s disease.
Prolonged respiratory paralysis may also occur in patients receiving concomitant neuromuscular blocking agents. If neuromuscular blockade occurs, it may be reversed by the administration of calcium salts but mechanical assistance may be necessary.
Bronchospasm Bronchospasm has been reported with inhalation of tobramycin.
In clinical studies with BETHKIS, bronchospasm was observed in one (0.5%) BETHKIS-treated patient and in no placebo-treated patients. Wheezing occurred in ten (5%) BETHKIS-treated patients and four (4%) placebo-treated patients. Bronchospasm and wheezing should be treated as medically appropriate.
Laboratory Tests Audiograms Clinical studies of inhaled tobramycin solutions did not identify
hearing loss using audiometric tests which evaluated hearing up to 8000 Hz. Physicians should consider an audiogram for patients who show any evidence of auditory dysfunction, or who are at increased risk for auditory dysfunction. Tinnitus may be a sentinel symptom of ototoxicity, and therefore the onset of this symptom warrants caution.
Serum Concentrations In patients with normal renal function treated with BETHKIS, serum tobramycin concentrations range from approximately 0.06-1.89 mcg/mL one hour after dose administration and do not require routine monitoring. Serum concentrations of tobramycin in patients with renal dysfunction or patients treated with concomitant parenteral tobramycin should be monitored at the discretion of the treating physician . The serum concentration of tobramycin should only be monitored through venipuncture and not finger prick blood sampling. Contamination of the skin of the fingers with tobramycin may lead to falsely increased measurements of serum levels of the drug.
This contamination cannot be completely avoided by hand washing before testing. Renal Function The clinical studies of BETHKIS did not reveal any imbalance in the percentage of patients who experienced at least a 50% rise in serum creatinine from baseline in either the BETHKIS group (n=26, 14%) or the placebo group (n=15, 13%). Laboratory tests of urine and renal function should be conducted at the discretion of the treating physician.
Embryo-Fetal Toxicity Aminoglycosides can cause fetal harm when administered to a pregnant
woman. Aminoglycosides cross the placenta, and streptomycin has been associated with several reports of total, irreversible, bilateral congenital deafness in pediatric patients exposed in utero. However, systemic absorption of tobramycin following inhaled administration is expected to be minimal . Patients who use BETHKIS during pregnancy, or become pregnant while taking BETHKIS should be apprised of the potential hazard to the fetus .
Concomitant Use of Systemic Aminoglycosides Patients receiving concomitant
BETHKIS and parenteral aminoglycoside therapy should be monitored as clinically appropriate for toxicities associated with aminoglycosides as a class. Serum tobramycin levels should be monitored.
Drug Interactions with Bethkis
Drugs with Neurotoxic, Nephrotoxic, or Ototoxic Potential Concurrent and/or sequential use of
BETHKIS with other drugs with neurotoxic, nephrotoxic, or ototoxic potential should be avoided.
Diuretics Some diuretics can enhance aminoglycoside toxicity by altering antibiotic concentrations in
serum and tissue. Therefore, BETHKIS should not be administered concomitantly with ethacrynic acid, furosemide, urea, or intravenous mannitol. The interaction between inhaled mannitol and BETHKIS has not been evaluated.
Pregnancy Safety for Bethkis
Pregnancy Risk Summary Aminoglycosides can cause fetal harm. Published literature reports that use of streptomycin, an aminoglycoside, can cause total, irreversible, bilateral congenital deafness when administered to a pregnant woman . Although there are no available data on use of BETHKIS in pregnant women to be able to inform a drug-associated risk of major birth defects, miscarriage, or adverse maternal or fetal outcomes, systemic absorption of tobramycin following inhaled administration is expected to be minimal . There are risks to the mother associated with cystic fibrosis in pregnancy (see Clinical Considerations). In animal reproduction studies with subcutaneous administration of tobramycin in pregnant rats and rabbits during organogenesis there were no adverse developmental outcomes; however, ototoxicity was not evaluated in the offspring from these studies (see Data ). Advise pregnant women of the potential risk to a fetus. The estimated background risk of major birth defects and miscarriage for the indicated populations are unknown.
All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. 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. Clinical Considerations Disease-Associated Maternal and/or Embryo/Fetal Risk Cystic fibrosis may increase the risk for preterm delivery.
Data Animal Data No reproduction toxicology studies have been conducted with inhaled tobramycin. However, subcutaneous administration of tobramycin at doses of up to 100 (rat) or 20 (rabbit) mg/kg/day during organogenesis was not associated with adverse developmental outcomes. Subcutaneous doses of tobramycin ≥ 40mg/kg/day were severely maternally toxic to rabbits and precluded the evaluation of adverse developmental outcomes.
Ototoxicity was not evaluated in offspring during nonclinical reproductive toxicity studies with tobramycin.
Pediatric Use of Bethkis
Pediatric Use The safety and efficacy of BETHKIS have not been studied in pediatric cystic fibrosis patients under six years of age.
Contraindications for Bethkis
is contraindicated in patients with a known hypersensitivity to any aminoglycoside. BETHKIS is contraindicated in patients with a known hypersensitivity to any aminoglycoside.
Overdosage Information for Bethkis
No overdoses have been reported with BETHKIS in clinical trials. Signs and symptoms of acute toxicity from overdosage of intravenous tobramycin might include dizziness, tinnitus, vertigo, loss of high-tone hearing acuity, respiratory failure, neuromuscular blockade, and renal impairment. Administration by inhalation results in low systemic bioavailability of tobramycin.
Tobramycin is not significantly absorbed following oral administration. Tobramycin serum concentrations may be helpful in monitoring overdosage. In all cases of suspected overdosage, physicians should contact the Regional Poison Control Center for information about effective treatment.
In the case of any overdosage, the possibility of drug interactions with alterations in drug disposition should be considered.
Clinical Studies of Bethkis
Two, double-blind, randomized, placebo-controlled, parallel group clinical studies (Study 1 and Study 2), which randomized and dosed 306 patients, were conducted in cystic fibrosis patients with P. aeruginosa. The osmolality of the drug formulation used in these studies differed from the to-be-marketed product. To rely upon the efficacy and safety established in the placebo-controlled studies, an additional study was conducted as a bridge to the to-be-marketed drug.
The bridging study assessed the efficacy and tolerability of aerosolized Tobramycin Inhalation Solution with osmolality similar to BETHKIS over a 4-week treatment in 324 patients with cystic fibrosis. Results of this study showed that the Tobramycin Inhalation Solution in this study had similar efficacy as that seen in the placebo-controlled studies. The compressors in the placebo-controlled studies and the bridging study differed from the PARI VIOS compressor to be used with BETHKIS. In vitro cascade impaction studies demonstrated that the various compressors used in the clinical trials delivered equivalent doses and respirable fractions of the to-be-marketed BETHKIS and TOBI with the marketed compressor (PARI VIOS) when used with the same nebulizer (PARI LC Plus Reusable nebulizer). All subjects enrolled in both efficacy studies had baseline FEV 1 % predicted ≥ 40% and ≤ 80% (mean baseline FEV 1 of 60% of predicted normal) and infected with P. aeruginosa.
Subjects who were less than 6 years of age, or who had a baseline creatinine of ≥ 1.5 mg/dL, or who had Burkholderia cepacia isolated from sputum were excluded. A total of 190 patients, 29 in Study 1 and 161 in Study 2, received BETHKIS therapy on an outpatient basis. Of these, 55% were males and 45% were females.
Eighty-two (43.2%) patients were between 6 and 12 years of age, 54 (28.4%) patients were between 13 and 17 years of age, and the remaining 54 (28.4%) patients were greater than 17 years of age. Of the patients who received BETHKIS, only 89.7% of patients in Study 1 had at least one concomitant medication, while all patients in Study 2 also received at least one concomitant medication. These concomitant medications include mucolytics, steroidal and nonsteroidal anti-inflammatory drugs, bronchodilators, rehabilitative physiotherapies and if necessary, antibiotics for bacterial infections other than P. aeruginosa.
Study 1 Study 1 was a double-blind, single cycle study that randomized 59 patients to receive BETHKIS (n=29) or placebo (n=30) for one cycle of treatment (28 days on treatment followed by 28 days off treatment). All patients were ≤ 30 years of age (mean age 12.6 years) and 46% were females. All randomized patients were included in the primary analysis except for one patient who had missing baseline information. BETHKIS significantly improved lung function compared with placebo as measured by the absolute change in FEV 1 % predicted from baseline to the end of Cycle 1 dosing in the primary analysis population.
Treatment with BETHKIS and placebo resulted in absolute increases in FEV 1 % predicted of 16% and 5%, respectively (LS mean difference = 11%; 95% CI: 3, 19; p=0.003). This analysis is adjusted for the covariate of baseline FEV 1 % predicted, using multiple imputation for missing data. Figure 1 shows the average change in FEV 1 % predicted over eight weeks. Study 2 Study 2 was a randomized, double-blind, 3-cycle, placebo-controlled trial.
A total of 247 eligible patients were randomized 2:1 to receive three cycles of BETHKIS (n=161) or placebo (n=86). As in Study 1, each cycle comprised 28 days on treatment followed by 28 days off treatment. All patients were ≤46 years of age (mean age 14.8 years) and 44.9% were females. In this study, two randomized patients in the placebo group were not included in the primary efficacy analysis; one withdrew consent without taking any trial medication and the other withdrew due to an adverse drug reaction.
BETHKIS significantly improved lung function compared with placebo as measured by the absolute change in FEV 1 % predicted from baseline to the end of Cycle 3 “ON” period. Treatment with BETHKIS and placebo resulted in absolute increases in FEV 1 % predicted of 7% and 1%, respectively (LS mean difference = 6%; 95% CI: 3, 10; p<0.001). This analysis is adjusted for the covariate of baseline FEV 1 % predicted, using multiple imputation for missing data. Figure 1 shows the average change in FEV 1 % predicted over 24 weeks from Study 2. Figure 1: FEV 1 % of Predicted Normal – Absolute Change from Baseline (Adjusted mean) - ITT Population In Study 2, 9.9% of patients treated with BETHKIS and 24.7% of patients who received placebo had unplanned hospitalizations due to the disease.
Also in Study 2, 6.2% of patients treated with BETHKIS and 16.5% of placebo patients received parenteral tobramycin. Figure 1
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.
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