Rifabutin is generaly well tolerated. Some of the adverse reactions reported are- Flu-like syndrome, hepatitis, hemolysis, arthralgia, myositis, chest pressure or pain with dyspnea, skin discoloration, seizure, parathesia, confusion, non-specific T wave changes on ECG.

Drug/Food interactions- High fat meals slow the rate of absorption without influencing the extent. Rifabutin doses may be mixed with foods such as apple sauce.

Hypersenstivity to the drug or to any of their rifamycins

Special precautions-

Monitoring- Because rifabutim n may be associated with neutropenia, and more rarely thrombocytopenia, consider obtaining hematologic studies periodically in patients receiving prophylaxis.

Warnings-

Active tuberculosis- rifabutin prophylaxis must not be administered to patients with active tuberculosis. Immediately evaluate patients who develop complaints consistent with active tuberculosis while on rifabutin prophylaxis so that with active disease may be given an effective combination regimen of antituberculosis medication.

Fertility impairment- fertility was impaired in male rats given 160mg/kg (32 times the recommended human daily dose)

Pregnancy- Use in pregnant women only if the potential benefit justifies the potential risk to the fetus.

Lactation- Decide whether to discontinue the drug or discontinue nursing, taking into account the importance of the drug to the mother.

Children- Safety and efficacy in children have not been established.

Indications:

Prevention of disseminated Mycobacterium avium complex (MAC ) disease in patients with advanced HIV infection

Dosage:

Usual dose- 300mg once daily at doses of 150mg twice daily

Overdosage- Treatment-

1.No experience in the treatment of overdose with rifabutin.

2. Clinical experience with rifamycins suggest that gastric lavage to evaciuate gastric contents (within a few hours of overdose) followed by instillation of an activated charcoal slurry into stomach, may help absorb, any remaining drug from the GI tract

3. Hemodoalysis nor forced diuresis is expected to enhance the systemic elimination of unchanged rifabutin from the body in a patient with rifabutin overdose.

Missed dose-

1. If you miss a dose of this medicine, take it as soon as possible.

2. However, if it is almost time for next dose, skip the missed dose and go back to your regular dosing schedule.

3. Do not double doses.

1. Advise patients of the signs and synptoms of both MAc and tubrerculosis, and instruct them to consult their physician, if they develop new complaints consistent with either of these diseases.

2. Since, Ribabutin may rarely be associated with myosistis and uveitis, advise patients to notify their physicians if they develop signs or symptoms suggesting either of these disorders.

3. Urine, feces, saliva, sputum, pespiration, tears, and skin may colored brown-orange with rifabutin and some of its metabolites. Make patients aware of these disorders.

4. Patients using oral contraceptives should consider changing to non-hormnal methods of birth control since ribabutin, like rifampin, may decrease their efficacy

Pharmacology-

Rifabutin, an anti-mycobacterial agent, is a semisynthetic ansamysin antibiotic derved from rifamycin S, Rifabutin inhibits DNA -dependent RNA polymerase in suseptible strains of Escherericha coli, and Bacillus subtilis but not in mamalian cells.

Pharmcokinetics-

Following a single dose of 300mg to healthy volunteers rifabutin was readily absorbed from GI tract with mean plasma levels Cmax of 375ng.ml, attained in 3.3 hours.The mean terminal half-lfe is 45 hours (range 16 to 69 hours)

High fat meals slow the rate of absorption without influencing the extent. Rifabutin doses may be mixed with foods such as apple sauce.

Pregnancy:

Use in pregnant only if the potential benefit justifies the potential risk to the fetus

Lactation:

Not known whether Ribabutin is excreted in breast milk.

Use with caution on nursing mothers

Children-

Safety and efficacy in children have not been established.