Rifampicin Delavirdine

Delavirdine No Contraindicated because of the marked decrease in concentrations of delavirdine when administered with rifampicin... 

Concomitant use of inducers of cytochrome P450, such as rifampicin, rifabutin, phenytoin, phenobarbital, or carba-mazepine, should be avoided, since they significantly reduce delavirdine plasma concentrations (4). 

Rifabutin and rifampicin (rifampin) cause a very marked fall in delavirdine plasma levels rifabutin levels are raised when the delavirdine dose is increased to compensate for this. Rifabutin does not affect efavirenz levels, whereas efavirenz decreases rifabutin levels. There is usually no important interaction between rifabutin and nevirapine, although some patients may have a higher risk of rifabutin adverse effects. 

In a controlled study in 7 HIV-positive patients taking delavirdine mesilate 400 mg three times daily for 30 days, the addition of rifabutin 300 mg daily from days 16 to 30 eaused a fivefold increase in the delavirdine elearanee, and an 84% fall in the steady-state plasma levels. This was presumably due to the enzyme-indueing effeets of the rifabutin. A similar study using rifampicin in place of rifabutin found that rifampicin caused a 27-fold increase in clearance of delavirdine, and the steady-state plasma levels became almost undetectable. ... 

It has been recommended that the combination of delavirdine and rifampicin should be considered as contraindicated because the effects of the interaction are so large. The CDC in the US and the manufacturer recommend that neither rifabutin nor rifampicin should be used with delavirdine. 

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See also in sourсe #XX -- [ ]

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