Levofloxacin (Page 15 of 16)

14.9 Inhalational Anthrax (Post-Exposure)

The effectiveness of levofloxacin for this indication is based on plasma concentrations achieved in humans, a surrogate endpoint reasonably likely to predict clinical benefit. Levofloxacin has not been tested in humans for the post-exposure prevention of inhalation anthrax. The mean plasma concentrations of levofloxacin associated with a statistically significant improvement in survival over placebo in the rhesus monkey model of inhalational anthrax are reached or exceeded in adult and pediatric patients receiving the recommended oral and intravenous dosage regimens [see Indications and Usage (1.13) and Dosage and Administration (2.1, 2.2)].

Levofloxacin pharmacokinetics have been evaluated in adult and pediatric patients. The mean (± SD) steady state peak plasma concentration in human adults receiving 500 mg orally or intravenously once daily is 5.7 ± 1.4 and 6.4 ± 0.8 mcg/mL, respectively; and the corresponding total plasma exposure (AUC0 — 24 ) is 47.5 ± 6.7 and 54.6 ± 11.1 mcg.h/mL, respectively. The predicted steady-state pharmacokinetic parameters in pediatric patients ranging in age from 6 months to 17 years receiving 8 mg/kg orally every 12 hours (not to exceed 250 mg per dose) were calculated to be comparable to those observed in adults receiving 500 mg orally once daily [see Clinical Pharmacology (12.3)].

In adults, the safety of levofloxacin for treatment durations of up to 28 days is well characterized. However, information pertaining to extended use at 500 mg daily up to 60 days is limited. Prolonged levofloxacin therapy in adults should only be used when the benefit outweighs the risk.

In pediatric patients, the safety of levofloxacin for treatment durations of more than 14 days has not been studied. An increased incidence of musculoskeletal adverse events (arthralgia, arthritis, tendinopathy, gait abnormality) compared to controls has been observed in clinical studies with treatment duration of up to 14 days. Long-term safety data, including effects on cartilage, following the administration of levofloxacin to pediatric patients is limited [see Warnings and Precautions (5.10), Use in Specific Populations (8.4)].

A placebo-controlled animal study in rhesus monkeys exposed to an inhaled mean dose of 49 LD50 (~2.7 X 106) spores (range 17 to 118 LD50 ) of B. anthracis (Ames strain) was conducted. The minimal inhibitory concentration (MIC) of levofloxacin for the anthrax strain used in this study was 0.125 mcg/mL. In the animals studied, mean plasma concentrations of levofloxacin achieved at expected Tmax (one hour post-dose) following oral dosing to steady-state ranged from 2.79 to 4.87 mcg/mL. Steady-state trough concentrations at 24 hours post-dose ranged from 0.107 to 0.164 mcg/mL. Mean (SD) steady-state AUC0 to 24 was 33.4 ± 3.2 mcg.h/mL (range 30.4 to 36 mcg.h/mL). Mortality due to anthrax for animals that received a 30-day regimen of oral levofloxacin beginning 24 hrs post-exposure was significantly lower (1/10), compared to the placebo group (9/10) [P = 0.0011, 2-sided Fisher’s Exact Test]. The one levofloxacin treated animal that died of anthrax did so following the 30-day drug administration period.

15 REFERENCES

1. Clinical and Laboratory Standards Institute. Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria That Grow Aerobically. Approved Standard – Eighth Edition. Clinical and Laboratory Standards Institute document M7-A8, Vol. 29, No. 2, CLSI, Wayne, PA, January 2009.

2. Clinical and Laboratory Standards Institute. Performance Standards for Antimicrobial Disk Susceptibility Tests. Approved Standard – Tenth Edition. Clinical and Laboratory Standards Institute document M2-A10, Vol. 29, No. 1, CLSI, Wayne, PA, January 2009.

16 HOW SUPPLIED/STORAGE AND HANDLING

16.1 Levofloxacin Tablets

Levofloxacin Tablets are available containing 250 mg or 500 mg of levofloxacin, USP.

The 250 mg tablets are yellow film-coated, round, unscored tablets debossed with M on one side of the tablet and 1215 on the other side. They are available as follows:

NDC 51079-034-20 — Unit dose blister packages of 100 (10 cards of 10 tablets each).

The 500 mg tablets are yellow film-coated, modified capsule shaped, unscored tablets debossed with M 1217 on one side of the tablet and blank on the other side. They are available as follows:

NDC 51079-035-20 — Unit dose blister packages of 100 (10 cards of 10 tablets each).

Store at 20° to 25°C (68° to 77°F). [See USP Controlled Room Temperature.]

17 PATIENT COUNSELING INFORMATION

See FDA-Approved Medication Guide (17.5)

17.1 Antibacterial Resistance

Antibacterial drugs including levofloxacin should only be used to treat bacterial infections. They do not treat viral infections (e.g., the common cold). When levofloxacin is prescribed to treat a bacterial infection, patients should be told that although it is common to feel better early in the course of therapy, the medication should be taken exactly as directed. Skipping doses or not completing the full course of therapy may (1) decrease the effectiveness of the immediate treatment and (2) increase the likelihood that bacteria will develop resistance and will not be treatable by levofloxacin or other antibacterial drugs in the future.

17.2 Administration with Food, Fluids and Concomitant Medications

Patients should be informed that levofloxacin tablets may be taken with or without food. The tablet should be taken at the same time each day.

Patients should drink fluids liberally while taking levofloxacin tablets to avoid formation of a highly concentrated urine and crystal formation in the urine.

Antacids containing magnesium or aluminum, as well as sucralfate, metal cations such as iron, and multivitamin preparations with zinc or didanosine should be taken at least 2 hours before or 2 hours after oral levofloxacin tablet administration.

17.3 Serious and Potentially Serious Adverse Reactions

Patients should be informed of the following serious adverse reactions that have been associated with levofloxacin or other fluoroquinolone use:

  • Tendon Disorders: Patients should contact their healthcare provider if they experience pain, swelling, or inflammation of a tendon, or weakness or inability to use one of their joints; rest and refrain from exercise; and discontinue levofloxacin treatment. The risk of severe tendon disorders with fluoroquinolones is higher in older patients usually over 60 years of age, in patients taking corticosteroid drugs, and in patients with kidney, heart or lung transplants.
  • Exacerbation of Myasthenia Gravis: Patients should inform their physician of any history of myasthenia gravis. Patients should notify their physician if they experience any symptoms of muscle weakness, including respiratory difficulties.
  • Hypersensitivity Reactions: Patients should be informed that levofloxacin can cause hypersensitivity reactions, even following the first dose. Patients should discontinue the drug at the first sign of a skin rash, hives or other skin reactions, a rapid heartbeat, difficulty in swallowing or breathing, any swelling suggesting angioedema (e.g., swelling of the lips, tongue, face, tightness of the throat, hoarseness) or other symptoms of an allergic reaction.
  • Hepatotoxicity: Severe hepatotoxicity (including acute hepatitis and fatal events) has been reported in patients taking levofloxacin. Patients should inform their physician and be instructed to discontinue levofloxacin treatment immediately if they experience any signs or symptoms of liver injury including: loss of appetite, nausea, vomiting, fever, weakness, tiredness, right upper quadrant tenderness, itching, yellowing of the skin and eyes, light colored bowel movements or dark colored urine.
  • Convulsions: Convulsions have been reported in patients taking fluoroquinolones, including levofloxacin. Patients should notify their physician before taking this drug if they have a history of convulsions.
  • Neurologic Adverse Effects (e.g., dizziness, lightheadedness, increased intracranial pressure): Patients should know how they react to levofloxacin before they operate an automobile or machinery or engage in other activities requiring mental alertness and coordination. Patients should notify their physician if persistent headache with or without blurred vision occurs.
  • Diarrhea: Diarrhea is a common problem caused by antibiotics which usually ends when the antibiotic is discontinued. Sometimes after starting treatment with antibiotics, patients can develop watery and bloody stools (with or without stomach cramps and fever) even as late as 2 or more months after having taken the last dose of the antibiotic. If this occurs, patients should contact their physician as soon as possible.
  • Peripheral Neuropathies: If symptoms of peripheral neuropathy including pain, burning, tingling, numbness and/or weakness develop, patients should discontinue treatment and contact their physician.
  • Prolongation of the QT Interval: Patients should inform their physician of any personal or family history of QT prolongation or proarrhythmic conditions such as hypokalemia, bradycardia or recent myocardial ischemia; if they are taking any Class IA (quinidine, procainamide) or Class III (amiodarone, sotalol) antiarrhythmic agents. Patients should notify their physicians if they have any symptoms of prolongation of the QT interval, including prolonged heart palpitations or a loss of consciousness.
  • Musculoskeletal Disorders in Pediatric Patients: Parents should inform their child’s physician if their child has a history of joint-related problems before taking this drug. Parents of pediatric patients should also notify their child’s physician of any tendon or joint-related problems that occur during or following levofloxacin therapy [see Warnings and Precautions (5.10) and Use in Specific Populations (8.4)].
  • Photosensitivity/Phototoxicity: Patients should be advised that photosensitivity/phototoxicity has been reported in patients receiving fluoroquinolone antibiotics. Patients should minimize or avoid exposure to natural or artificial sunlight (tanning beds or UVA/B treatment) while taking fluoroquinolones. If patients need to be outdoors when taking fluoroquinolones, they should wear loose-fitting clothes that protect skin from sun exposure and discuss other sun protection measures with their physician. If a sunburn-like reaction or skin eruption occurs, patients should contact their physician.

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