Kitabis Pak (Page 2 of 5)

6.2 Postmarketing Experience

The following adverse reactions have been identified during post approval 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: Some of these reports occurred in patients with previous or concomitant treatment with systemic aminoglycosides. Patients with hearing loss frequently reported tinnitus. [see Warnings and Precautions (5.2)]

Skin and subcutaneous tissue disorders

Hypersensitivity, pruritus, urticaria, rash

Nervous system disorders

Aphonia, dysgeusia

Respiratory, thoracic, and mediastinal disorders

Bronchospasm [see Warnings and Precautions (5.1)] , oropharyngeal pain

7 DRUG INTERACTIONS

7.1 Drugs with Neurotoxic, Nephrotoxic or Ototoxic Potential

Concurrent and/or sequential use of tobramycin inhalation solution with other drugs with neurotoxic, nephrotoxic, or ototoxic potential should be avoided if possible.

7.2 Diuretics

Some diuretics can enhance aminoglycoside toxicity by altering aminoglycoside concentrations in serum and tissue. Tobramycin inhalation solution should not be administered concomitantly with ethacrynic acid, furosemide, urea, or intravenous mannitol.

8 USE IN SPECIFIC POPULATIONS

8.1 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 [Warnings and Precautions (5.5)]. Although there are no available data on KITABIS PAK use in pregnant women 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 [see Clinical Pharmacology (12.3)]. 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 reproductive toxicity studies have been conducted with tobramycin inhalation solution. 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 ≥40 mg/kg/day were severely maternally toxic to rabbits and precluded the evaluation of adverse developmental outcomes. Ototoxicity was not evaluated in offspring during non-clinical reproductive toxicity studies with tobramycin.

8.2 Lactation

Risk Summary

There are no data on the presence of tobramycin inhalation solution in either human or animal milk, the effects on the breastfed infant, or the effects on milk production. Limited published data on other formulations of tobramycin in lactating women indicate that tobramycin is present in human milk. However, systemic absorption of tobramycin following inhaled administration is expected to be minimal [see Clinical Pharmacology (12.3)]. Tobramycin may cause alteration in the intestinal flora of the breastfeeding infant (see Clinical Considerations). The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for KITABIS PAK and any potential adverse effects on the breastfed infant from KITABIS PAK or from the underlying maternal condition.

Clinical Considerations

Tobramycin may cause intestinal flora alteration. Advise a woman to monitor the breastfed infant for loose or bloody stools and candidiasis (thrush, diaper rash).

8.4 Pediatric Use

The safety and efficacy of tobramycin inhalation solution have not been studied in pediatric patients under 6 years of age.

8.5 Geriatric Use

Clinical studies of tobramycin inhalation solution did not include patients aged 65 years and over. Tobramycin is known to be substantially excreted by the kidney, and the risk of adverse reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, it may be useful to monitor renal function [see Warnings and Precautions (5.3)].

10 OVERDOSAGE

Signs and symptoms of acute toxicity from overdosage of IV tobramycin might include dizziness, tinnitus, vertigo, loss of high-tone hearing acuity, respiratory failure, and neuromuscular blockade. 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.

11 DESCRIPTION

KITABIS PAK contains tobramycin inhalation solution, USP and the PARI LC PLUS Reusable Nebulizer (PARI LC PLUS). Tobramycin inhalation solution is a sterile, clear, slightly yellow, non-pyrogenic, aqueous solution with the pH and salinity adjusted specifically for administration by a compressed air driven PARI LC PLUS Reusable Nebulizer. The chemical formula for tobramycin is C H N O and the molecular weight is 467.52. Tobramycin is

O-3-amino-3-deoxy-α-D-glucopyranosyl-(1→4)-O-[2,6-diamino-2,3,6-trideoxy-a-D-ribo — hexopyranosyl-(1→6)]-2-deoxy-L-streptamine. The structural formula for tobramycin is:

Structural Formula
(click image for full-size original)

Each single-use 5 mL ampule contains 300 mg tobramycin and 11.25 mg sodium chloride in sterile water for injection. Sulfuric acid and sodium hydroxide are added to adjust the pH to 6.0. Nitrogen is used for sparging. The formulation contains no preservatives. The inhalation solution has an osmolality in the range 135 to 200 mOsmol/kg.

The PARI LC PLUS Reusable Nebulizer has the following performance characteristics with tobramycin inhalation solution [measured using Next Generation Impactor (NGI) at 15 L/min continuous flow, standard conditions (50%RH, 23°C)]: (1) Delivered Dose: 174 mg; (2) Fine Particle Dose (< 5μm): 97 mg; (3) Nebulization Time: 13 min.; (4) Mass Median Aerodynamic Diameter: 4.3 μm; (5) Geometric Standard Deviation (GSD): 2.2 μm.

12 CLINICAL PHARMACOLOGY

12.1 Mechanism of Action

Tobramycin is an aminoglycoside antibacterial [see Microbiology (12.4)].

12.3 Pharmacokinetics

Absorption

Tobramycin inhalation solution contains tobramycin, a cationic polar molecule that does not readily cross epithelial membranes.1 The bioavailability of tobramycin inhalation solution may vary because of individual differences in nebulizer performance and airway pathology. 2 Following administration of tobramycin inhalation solution, tobramycin remains concentrated primarily in the airways.

Sputum Concentrations

Ten minutes after inhalation of the first 300 mg dose of tobramycin inhalation solution, the average concentration of tobramycin was 1237 mcg/g (ranging from 35 to 7414 mcg/g) in sputum. Tobramycin does not accumulate in sputum; after 20 weeks of therapy with the tobramycin inhalation solution regimen, the average concentration of tobramycin at ten minutes after inhalation was 1154 mcg/g (ranging from 39 to 8085 mcg/g) in sputum. High variability of tobramycin concentration in sputum was observed. Two hours after inhalation, sputum concentrations declined to approximately 14% of tobramycin levels at ten minutes after inhalation.

Serum Concentrations

The average serum concentration of tobramycin one hour after inhalation of a single 300 mg dose of tobramycin inhalation solution by cystic fibrosis patients was 0.95 mcg/mL. After 20 weeks of therapy on the tobramycin inhalation solution regimen, the average serum tobramycin concentration one hour after dosing was 1.05 mcg/mL.

Distribution

Following administration of tobramycin inhalation solution, tobramycin remains concentrated primarily in the airways. Binding of tobramycin to serum proteins is negligible.

Elimination

Metabolism

Tobramycin is not metabolized.

Excretion

The elimination half-life of tobramycin from serum is approximately 2 hours after intravenous (IV) administration. Assuming tobramycin absorbed following inhalation behaves similarly to tobramycin following IV administration, systemically absorbed tobramycin is eliminated principally by glomerular filtration. Unabsorbed tobramycin, following tobramycin inhalation solution administration, is likely eliminated primarily in expectorated sputum.

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