Drug Monograph on Rifampicin - page 7
Keywords: rifampicin, drug monograph, pharmacology, efficay, therapeutic uses, pharmacodynamics, Prophylaxis of meningococcal meningitis rifampin rifadin SA infections tuberculosis essay on rifampicin pharmacokinetics absorption distribution matabolism excretion bmj referecing
By Einstein10 on 30/12/2009
Level: Foundation Degree
Page Number: 7 of 11 pages: 1 2 3 4 5 6 7 8 9 10 11
sensitivity and can result in thrombocytopenic purpura, in the case of which the drug should be ceased and not administered further. There have been reports of cerebral haemorrhage as well as other fatalities when rifampicin has continued to be administered despite the appearance of purpura. Harmless orange/pink colour to bodily fluids including sweat, tears, urine.
Soft contact lenses can be permanently stained
Common side effects include: GI effects including anorexia, nausea, abdominal discomfort, vomiting, and diarrhoea 6,7 headache, drowsiness 7,8
Table 8- 33,38 Adverse Drug Reactions of Rifampicin
Drug Interactions
Rifampicin activates the nuclear pregnane X receptor (PXR), which induces a change in activity within the cytochromes P450, glucuronosyltransferases and p-glycoprotein 39.
Rifampicin is a potent inducer of Cytochrome P450 enzymes 39, and this induction results from the activation of PXR. The activated PXR then functions as a ligand activated transcription factor, and on binding to the PXR receptor activates the transcription of CYP 3A4 and many other genes2.
UGT-glucuronosyltransferase 1A can be induced by rifampicin. 40 This compound metabolises drugs and other compounds via glucuronidation. Induction of increased amounts of UGT may result in increased rates of clearance of drugs as well as other substances e.g steroids, toxins 41.
Potentially hazardous interactions 35-41
Drug Reaction
rosiglitazone rifampicin reduced the plasma concentrations of rosiglitazone by 65% and the half-life from 3.9-1.5 hours. Rosiglitazone is a thiazolidinedione and is metabolised by CYP 2c8 and CYP2C9
cyclosporine
Cyclosporine is an immunosuppressant and is primarily metabolised by CYP3A4 in the liver. Concomitant use of cyclosporine and rifampicin resulted in the dose of cyclosporine to be increased approximately 3 fold in order to maintain the therapeutic effect
Simvastatin
Simvastatin is used to treat elevated levels of cholesterol and is metabolised by CYP3A4.
Using simvastatin alongside rifampicin leads to decreased efficacy of simvastatin.
A study showed that treating healthy volunteers with rifampicin at a dose of 600mg daily for 5 days and then giving the subjects a single 40mg dose of simvastatin reduced plasma concentrations of simvastatin by 87% in comparison to the control group
antidiabetic drugs
Rifampicin reduces the serum levels and the potential of some antidiabetic drugs (Sulfonylurea’s, thiazolidinedione) to lower blood glucose levels
antiepileptic drugs Reduce the efficacy of anti-epileptic drugs e.g. phenytoin by reducing serum levels of the drug and therefore induce fits
Contra-indications
Rifampicin is contraindicated in patients with known hypersensitivy to the drug or any of its excipients 42
Jaundice 42
In patients with severe hepatic disease
Contra-indicated when given alongside saquinavir/ritonavir as this combination increases the risk of hepatotoxicity 43
Rifampicin
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