 Rifampicin
Bactericidal
action against a wide range of organisms. Can kill intracellular
organisms as also semidormant or persistant ones. Generally reserved
for treatment of tuberculosis and leprosy and opportunistic atypical
mycobacterial infections suck as those in HIV positive or AIDS patients.
Inhibits the enzyme DNA-dependent RNA polymerase resulting in suppression
of nucleic acid synthesis.
Indications
& Dosage:
Oral
–
Tuberculosis: Part of multidrug regimens. Adults 450 or 600mg/day
for the first 2 months and then 10-15mg/kg three times a week for
further 4-6 months. Max 900mg/day. Children:10-20 mg/kg daily. Max:
600mg/day.
Leprosy: Given along with clofazimine and dapsone. Adults over 35kg:
450mg once a month. Children 10-14 years: 450mg once a month. Low
weight:12-15 mg/kg once a month.
Prophylaxis of Meningococcal Infections:Adults: 600mg b.i.d. Infants:
3-12 months:5 mg/kg b.i.d. Prophylaxis of Meningitis due to H.Influenzae
Type B: 20mg/kg once a day for 4 days. Neonates under 1 month: 10mg/kg/day.
Composition:
Each
Capsule Contains
(a)
Rifampicin B.P. 300mg.
(b)
Rifampicin B.P. 450mg.
Composition
(Suspension 60ml):
Each
5ml SUSP contains
Rifampicin
100mg.
Safety
Alert:
CL:
Hypersens to erythromycin. History of jaundice.
SP: Cholestatic hepatitis & reversible abnormalities
in LFT may be associated with prolonged or repeated therapy. History
of hepatic disorders. Pregnancy, lactation.
INT POT-HAZ: Reduces therapeutic effect of penicillins.
May potentiate action of carbamazepine, cyclosporine, theophylline
and warfarin. Terfenqdine toxicity increased. Others – theophylline
reduces plasma concentration of erythromycin. Increases serum digoxin
levels. Antibacterialactivity potentiated by acetazolamide and sodium
bicarbonate.
ADR POT-LT: Hepatotoxicity-cholestatic jaundice,
raised serum transaminases and eosinophilia. Rarely Stevens-Johnsons
syndrome. Others – Rash, Nausea, vomiting, G.I. discomfort,
ototoxicity with high doses and associated renal failure.
LAB INT: False elevation of plasma-glutamic oxaloacetic
transaminase if a colorimetric assay is used.
INT FOOD: Absorption affected to variable extent
for different esters.
Base: Rate but not extent of absorption reduced.
Estolate: Peak levels and bioavailabilty increased.
Ethylsuccinate: Peak levels and bioavailabilty reduced.
Stearate: Bioavailability increased immediately before food but
reduced when taken after food.
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