Bronchitol (Page 2 of 5)

7 DRUG INTERACTIONS

No formal drug interaction studies have been conducted with mannitol, the active ingredient in BRONCHITOL.

8 USE IN SPECIFIC POPULATIONS

8.1 Pregnancy

Risk Summary

There are no adequate and well-controlled studies of BRONCHITOL in pregnant women. The available data on BRONCHITOL use in pregnant women are not sufficient to inform any drug-associated risks for major birth defects and miscarriage. Based on animal reproduction studies, no evidence of structural alterations was observed when mannitol was administered to pregnant rats and mice during organogenesis at doses up to approximately 20 and 10 times, respectively, the maximum recommended daily inhalation dose (MRDID) in humans [see Data ]. There are risks to the mother associated with cystic fibrosis in pregnancy [see Clinial Considerations]. BRONCHITOL should be used during pregnancy only if the potential benefit justifies the potential risk to the mother and fetus.

The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the United States 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

In animal reproduction studies, oral administration of mannitol to pregnant rats and mice during the period of organogenesis did not cause fetal structural alterations. The mannitol dose in rats and mice was approximately 20 and 10 times the maximum recommended human daily inhalation dose (MRDID) in humans, respectively, (on a mg/m² basis at maternal doses of 1600 mg/kg/day in both species).

8.2 Lactation

Risk Summary

It is not known whether BRONCHITOL is excreted in human breast milk. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for BRONCHITOL and any potential adverse effects on the breastfed child from BRONCHITOL or from the underlying maternal condition.

8.4 Pediatric Use

BRONCHITOL is not indicated for use in children and adolescents. The safety and effectivenss of BRONCHITOL have not been established in pediatric patients for cystic fibrosis. Patients aged 6 years to 17 years were included in two 26-week, double-blind clinical trials (Trials 2 and 3). In these trials, 154 patients under 18 years of age received BRONCHITOL and 105 patients received control (50 mg inhaled mannitol). Hemoptysis was reported in 12 of 154 (7.8%) patients who received BRONCHITOL and in 2 of 105 (1.9%) patients who received control.

8.5 Geriatric Use

Clinical trials of BRONCHITOL did not include sufficient numbers of patients with cystic fibrosis who were 65 years of age and older to allow evaluation of safety and efficacy in this population.

8.6 Hepatic and Renal Impairment

Clinical trials of BRONCHITOL did not include patients with hepatic or renal impairment. No specific dose recommendations for these patient populations are available. However, an increase in systemic exposure of mannitol can be expected in patients with renal impairment based on the kidney being its primary route of elimination.

10 OVERDOSAGE

Susceptible persons may experience bronchoconstriction from an overdosage. If excessive coughing and bronchoconstriction occurs, immediately administer an inhaled short-acting bronchodilator and other medical treatments as necessary.

11 DESCRIPTION

BRONCHITOL (mannitol) inhalation powder contains D-Mannitol (referred to throughout as mannitol) as the active ingredient. Mannitol is a hexahydric sugar alcohol, with the following chemical name hexane-1,2,3,4,5,6-hexol and chemical structure:

Mannitol is a white or almost white crystalline powder or free-flowing granules with an empirical formula of C₆ H₁₄ O₆ and molecular weight of 182.2. Mannitol is freely soluble in water, and very slightly soluble in alcohol. Mannitol shows polymorphism.

BRONCHITOL contains mannitol powder spray dried into particles of respirable size filled into clear, colorless hard gelatin capsules. There are no inactive ingredients in BRONCHITOL.

The accompanying white plastic inhaler is comprised of a mouthpiece, blue piercing buttons, capsule chamber, and a removable cap. A blister pack consists of 10 capsules, each containing 40 mg mannitol. After a capsule is placed in the capsule chamber and pierced by firmly pressing and releasing the buttons on the side of the device, the powder within the capsule becomes exposed and ready for dispersion into the airstream generated by the patient upon inhalation through the mouthpiece. Under standardized in vitro test conditions, the inhaler delivers 32.2 mg of mannitol per inhalation when tested at a flow rate of 60 L/min for 2 seconds. The actual amount of drug delivered to the lungs will depend on patient factors, such as inspiratory flow profile.

12 CLINICAL PHARMACOLOGY

12.1 Mechanism of Action

The precise mechanism of action of BRONCHITOL in improving pulmonary function in cystic fibrosis patients is unknown.

12.2 Pharmacodynamics

The pharmacodynamics of mannitol are unknown.

12.3 Pharmacokinetics

Absorption

Following oral inhalation of 635 mg, the mean mannitol peak plasma concentration (Cmax) was 13.71 mcg/mL while the mean extent of systemic exposure (AUC) was 73.15 mcg•hr/mL. The mean time to peak plasma concentration (Tmax) after oral inhalation was 1.5 hour.

Distribution

Based on intravenous administration, the volume of distribution of mannitol was 34.3 L.

Elimination

Metabolism

Mannitol is metabolized in a CYP-independent manner through the glycolytic pathway via dehydrogenation to fructose. The extent of metabolism of mannitol appears to be small. This is evident from a urinary excretion of about 87% of unchanged drug after an intravenous dose to healthy patients.

Excretion

Following oral inhalation, the elimination half-life of mannitol was 4.7 hours. The mean terminal elimination half-life for mannitol in plasma remained unchanged regardless of the route of administration (oral, inhalation, and intravenous). The urinary excretion rate versus time profile for mannitol was consistent for all routes of administration. The total clearance after intravenous administration was 5.1 L/hr while the renal clearance was 4.4 L/hr. Therefore, the clearance of mannitol was predominately via the kidney. Following inhalation of 635 mg of mannitol in 18 healthy patients, about 55% of the total dose was excreted in the urine as unchanged mannitol. Following oral or intravenous administration of a 500 mg dose, the corresponding values were 54% and 87% of the dose, respectively.

Specific Populations

Patients with Hepatic and Renal Impairment: Formal pharmacokinetic studies using BRONCHITOL have not been conducted in patients with hepatic or renal impairment. Since the drug is eliminated primarily via the kidney, an increase in systemic exposure can be expected in renally impaired patients.

Drug Interaction Studies

No formal drug interaction studies have been conducted with BRONCHITOL.

13 NONCLINICAL TOXICOLOGY

13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility

Carcinogenesis

In 2-year carcinogenicity studies in rats and mice mannitol did not show evidence of carcinogenicity at oral dietary concentrations up to 5% (or 7,500 mg/kg on a mg/kg basis). These doses were approximately 55 and 30 times the MRHDID, respectively, on a mg/m² basis.

Mutagenesis

Mannitol tested negative in the following assays: bacterial gene mutation assay, in vitro mouse lymphoma assay, in vitro chromosomal aberration assay in WI-38 human cells, in vivo chromosomal aberration assay in rat bone marrow, in vivo dominant lethal assay in rats, and in vivo mouse micronucleus assay.

Impairment of Fertility

The effect of inhaled mannitol on fertility has not been investigated.