Rifabutin

Rifabutin capsules are indicated for the prevention of disseminated Mycobacterium avium complex (MAC) disease in patients with advanced HIV infection.

• It is recommended that rifabutin capsules be administered at a dose of 300 mg once daily
• For those patients with propensity to nausea, vomiting, or other gastrointestinal upset, administration of rifabutin at doses of 150 mg twice daily taken with food may be useful
• Doses of Rifabutin capsules may be administered mixed with foods such as applesauce
• For patients with severe renal impairment (creatinine clearance less than 30 mL/min), consider reducing the dose of rifabutin by 50%, if toxicity is suspected
• No dosage adjustment is required for patients with mild to moderate renal impairment
• Reduction of the dose of rifabutin may also be needed for patients receiving concomitant treatment with certain other drugs (see PRECAUTIONS-Drug Interactions )
• Mild hepatic impairment does not require a dose modification
• The pharmacokinetics of rifabutin in patients with moderate and severe hepatic impairment is not known

• Safety and effectiveness of rifabutin for prophylaxis of MAC in children have not been established
• Limited safety data are available from treatment use in 22 HIV-positive children with MAC who received rifabutin in combination with at least two other antimycobacterials for periods from 1 to 183 weeks
• Mean doses (mg/kg) for these children were: 18.5 (range 15.0 to 25.0) for infants 1 year of age, 8.6 (range 4.4 to 18.8) for children 2 to 10 years of age, and 4.0 (range 2.8 to 5.4) for adolescents 14 to 16 years of age
• There is no evidence that doses greater than 5 mg/kg daily are useful. …

Clinical studies of rifabutin did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger patients. …

• Patients should be advised of the signs and symptoms of both MAC and tuberculosis, and should be instructed to consult their physicians if they develop new complaints consistent with either of these diseases
• In addition, since rifabutin may rarely be associated with myositis and uveitis, patients should be advised to notify their physicians if they develop signs or symptoms suggesting either of these disorders
• Urine, feces, saliva, sputum, perspiration, tears, and skin may be colored brown-orange with rifabutin and some of its metabolites
• Soft contact lenses may be permanently stained
• Patients to be treated with rifabutin should be made aware of these possibilities. …

• Rifabutin capsules are contraindicated in patients who have had clinically significant hypersensitivity to rifabutin or to any other rifamycins
• Rifabutin capsules are contraindicated in patients being treated with cabotegravir/rilpivirine prolonged-release injectable suspension (see PRECAUTIONS-Drug Interactions, Table 2 )

Effect of Rifabutin on the Pharmacokinetics of Other Drugs Rifabutin induces CYP3A enzymes and therefore may reduce the plasma concentrations of drugs metabolized by those enzymes. This effect may reduce the efficacy of standard doses of such drugs, which include itraconazole, clarithromycin, and saquinavir. Effect of Other Drugs on Rifabutin Pharmacokinetics Some drugs that inhibit CYP3A may significantly increase the plasma concentration of rifabutin. Therefore, carefully monitor for rifabutin associated adverse events in those patients also receiving CYP3A inhibitors, which include fluconazole and clarithromycin. …

Tuberculosis Rifabutin capsules must not be administered for MAC prophylaxis to patients with active tuberculosis. Patients who develop complaints consistent with active tuberculosis while on prophylaxis with rifabutin should be evaluated immediately, so that those with active disease may be given an effective combination regimen of anti-tuberculosis medications. Administration of rifabutin as a single agent to patients with active tuberculosis is likely to lead to the development of tuberculosis that is resistant both to rifabutin and to rifampin. There is no evidence that rifabutin is an effective prophylaxis against M. tuberculosis . Patients requiring prophylaxis against both M. …

Adverse Reactions from Clinical Trials Rifabutin capsules were generally well tolerated in the controlled clinical trials. Discontinuation of therapy due to an adverse event was required in 16% of patients receiving rifabutin, compared to 8% of patients receiving placebo in these trials. Primary reasons for discontinuation of rifabutin were rash (4% of treated patients), gastrointestinal intolerance (3%), and neutropenia (2%). The following table enumerates adverse experiences that occurred at a frequency of 1% or greater, among the patients treated with rifabutin in studies 023 and 027. …

Pregnancy Rifabutin should be used in pregnant women only if the potential benefit justifies the potential risk to the fetus. There are no adequate and well-controlled studies in pregnant or breastfeeding women. Reproduction studies have been carried out in rats and rabbits given rifabutin using dose levels up to 200 mg/kg (about 6 to 13 times the recommended human daily dose based on body surface area comparisons). …

No information is available on accidental overdosage in humans. Treatment While there is no experience in the treatment of overdose with rifabutin capsules, clinical experience with rifamycins suggests that gastric lavage to evacuate gastric contents (within a few hours of overdose), followed by instillation of an activated charcoal slurry into the stomach, may help absorb any remaining drug from the gastrointestinal tract. Rifabutin is 85% protein bound and distributed extensively into tissues (Vss:8 to 9 L/kg). …

تناولها عندما تتذكر، إلا إذا اقترب موعد الجرعة التالية. عندها تخطَّ الجرعة المنسية. لا تتناول جرعتين معًا أبدًا للتعويض. راجع النشرة، فبعض الأدوية مختلفة.