DELAVIRDINE IS AN INHIBITOR OF CYP3A ISOFORM AND OTHER CYP ISOFORMS TO A LESSER EXTENT INCLUDING CYP2C9, CYP2D6, AND CYP2C19. COADMINISTRATION OF RESCRIPTOR AND DRUGS PRIMARILY METABOLIZED BY CYP3A (E.G., HMG-COA REDUCTASE INHIBITORS, AND SILDENAFIL) MAY RESULT IN INCREASED PLASMA CONCENTRATIONS OF THE COADMINISTERED DRUG THAT COULD INCREASE OR PROLONG BOTH ITS THERAPEUTIC OR ADVERSE EFFECTS.
DELAVIRDINE IS METABOLIZED PRIMARILY BY CYP3A, BUT IN VITRO DATA SUGGEST THAT DELAVIRDINE MAY ALSO BE METABOLIZED BY CYP2D6. COADMINISTRATION OF RESCRIPTOR AND DRUGS THAT INDUCE CYP3A, SUCH AS RIFAMPIN, MAY DECREASE DELAVIRDINE PLASMA CONCENTRATIONS AND REDUCE ITS THERAPEUTIC EFFECT. COADMINISTRATION OF RESCRIPTOR AND DRUGS THAT INHIBIT CYP3A MAY INCREASE DELAVIRDINE PLASMA CONCENTRATIONS.
ANTICONVULSANT AGENTS: PHENYTOIN, PHENOBARBITAL, CARBAMAZEPINE , HERBAL PRODUCTS LIKE ST. JOHN'S WORT (HYPERICUM PERFORATUM) & ANTIMYCOBACTERIALS LIKE RIFABUTIN, RIFAMPIN MAY LEAD TO LOSS OF VIROLOGIC RESPONSE AND POSSIBLE RESISTANCE TO RESCRIPTOR OR TO THE CLASS OF NON -NUCLEOSIDE REVERSE TRANSCRIPTASE INHIBITORS.
ANTIHISTAMINES: ASTEMIZOLE, TERFENADINE, GI MOTILITY AGENT LIKE CISAPRIDE & NEUROLEPTIC LIKE PIMOZIDE ARE CONTRAINDICATED DUE TO POTENTIAL FOR SERIOUS AND/OR LIFE -THREATENING REACTIONS SUCH AS CARDIAC ARRHYTHMIAS.
ANTIMYCOBACTERIALS: RIFABUTIN, RIFAMPIN MAY LEAD TO LOSS OF VIROLOGIC RESPONSE AND POSSIBLE RESISTANCE TO RESCRIPTOR OR TO THE CLASS OF NON -NUCLEOSIDE REVERSE TRANSCRIPTASE INHIBITORS OR OTHER COADMINISTERED ANTIVIRAL AGENTS.
ERGOT DERIVATIVES: DIHYDROERGOTAMINE, ERGONOVINE, ERGOTAMINE, METHYLERGONOVINE CONTRAINDICATED DUE TO POTENTIAL FOR SERIOUS AND/OR LIFE -THREATENING REACTIONS SUCH AS ACUTE ERGOT TOXICITY CHARACTERIZED BY PERIPHERAL VASOSPASM AND ISCHEMIA OF THE EXTREMITIES AND OTHER TISSUES.
HMG -COA REDUCTASE INHIBITORS LIKE LOVASTATIN, SIMVASTATIN, ATORVASTATIN & CERIVASTATIN: POTENTIAL FOR SERIOUS REACTIONS SUCH AS RISK OF MYOPATHY INCLUDING RHABDOMYOLYSIS.
SEDATIVE/HYPNOTICS: ALPRAZOLAM, MIDAZOLAM, TRIAZOLAM, CONTRAINDICATED DUE TO POTENTIAL FOR SERIOUS AND/OR LIFE -THREATENING REACTIONS SUCH AS PROLONGED OR INCREASED SEDATION OR RESPIRATORY DEPRESSION.