Codeine Rifampin

D6 Tricyclic antidepressants (TCAs), benztropine, perphenazine, clozapine, haloperidol, codeine/oxycodone, risperidone, class Ic antiarrhythmics, 3 blockers, trazodone, paroxetine, maprotiline, amoxapine, duloxetine, mirtazapine (partly), venlafaxine, bupropion Fluoxetine, paroxetine, duloxetine, hydroxybupropion, methadone, cimetidine, haloperidol, quinidine, ritonavir Phenobarbital, rifampin... 

Caraco Y, Sheller J, Wood AJJ. Pharmacogenetic determinants of codeine induction by rifampin The impact on codeine s respiratory, psychomotor... 

Opioids 2-3 days typically Up to 6 days with sustained-release formulations Up to 1 week with prolonged or heavy use Since the assay was made to detect morphine, detection of other opioids, such as codeine, oxycodone, hydrocodone, and other semisynthetic opioids, may be limited. Some synthetic opioids, e.g., fentanyl and meperidine, may not be detected. Drugs such as rifampin and some fluoroquinolones may cause false-positive results depending on the assay. 

Zidovudine (AZT) is an HIV reverse transcriptase inhibitor and chain terminator that is extensively glucuronidated (70% of the dose) primarily by UGT2B7. Metabolism of AZT is induced by rifampin (PXR), ritonavir, tipranavir, and efavirenz. Zidovudine clearance is inhibited by methadone (McCance-Katz, 1998) (opiates like codeine and morphine are UGT2B7 substrates), fluconazole Trapnell, 1998, atovaquone (Lee, 1996), and valproate (Lertora, 1994). Rifampin increased the formation clearance to AZT-glucuronide by twofold (Gallicano, 1999). 

As discussed above, the analgesic effect of codeine depends greatly on its abihty to be metabolized to morphine. In patients in whom large amounts of codeine have been administered without relief, the possibility of a polymorphism of the CYP2D6 enzyme must be considered. Medications that inhibit CYP2D6 may reduce or even completely block the conversion of codeine to morphine. These include selective serotonin reuptake inhibitors (SSRls), cimetidine, and antidepressants such as buproprion. On the other hand agents that induce CYP450 isozymes, such as rifampin and dexamethasone, increase the conversion rate and increase the risk of adverse events. 

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