Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0021051 (immunodeficiency)
 71,517 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The human immunodeficiency virus-1 protease inhibitor SD894 was evaluated as an inhibitor and inducer of cytochromes P450 (CYPs) in rats. After addition of 10 microM SD894 and 2 mM NADPH to liver microsomes from dexamethasone-treated rats, a type II spectrum appeared. Within 2 min, it was replaced by a type III spectrum, with absorbance maxima at 426 and 456 nm, similar to those observed with alkylamines (SKF-525A) and arylamines (p-chloroaniline). Preincubation of microsomes from dexamethasone-treated rats with SD894 and NADPH resulted in a time-dependent inhibition of testosterone 6beta-hydroxylation (CYP 3A1/2 activity), which was decreased to 25% of controls after 30 min. Testosterone 16beta-hydroxylation (CYP 2B1/2 activity) was unaffected under these conditions. Testosterone 6beta-hydroxylation rates in liver microsomes from pregnenolone 16alpha-carbonitrile-treated rats incubated with 10 microM SD894 and NADPH, washed, and reisolated by ultracentrifugation were reduced by 71%, whereas 16beta-hydroxylation was unaffected by SD894. Immunoblots of liver microsomes from rats dosed iv with SD894 or ip with TAO displayed increased CYP 2B1 and CYP 3A1 levels, respectively. Testosterone 6beta-hydroxylase activity in microsomes from TAO-treated rats was greater than controls. Preincubation of these microsomes with potassium ferricyanide produced an additional 50% increase, consistent with disruption of a metabolite-CYP complex. Microsomes from SD894-treated rats displayed a 3-fold increase in testosterone 16beta-hydroxylation. Potassium ferricyanide preincubation did not increase activity. Thus, although SD894 appears to inhibit CYP in vitro in a manner typical of other amine-containing, mechanism-based inhibitors, in vivo induction by 10 mg/kg daily doses of SD894 affects a different isozyme than does inhibition. The mechanism of induction is unknown.
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PMID:In vitro and in vivo effects of the arylamine human immunodeficiency virus protease inhibitor 4R-(4alpha,5alpha,6beta, 7beta)-1-[(3-(1-imidazoylcarbamoyl)phenyl)methyl]-3-[(3-aminophenyl)m ethyl]hexahydro-5,6-dihydroxy-4,7-bis(phenylmethyl)-2H-1, 3-diazepin-2-one (SD894) on rat hepatic cytochrome P450 2B and 3A. 939 33

DPC 681 (N-[(3-fluorophenyl)methyl]glycyl-N-[3-[((3-aminophenyl) sulfonyl)-2-(aminophenyl)amino]-(1S,2S)-2-hydroxy-1-(phenyl-methyl)propyl]-3-methyl-l-valinamide) is a potent peptide-like human immunodeficiency virus protease inhibitor that was evaluated in phase I clinical trials. In primary cultures of hepatocytes, DPC 681 significantly induced the testosterone 6beta-hydroxylase activity of rat CYP3A, but not human CYP3A4. Western blot analysis, however, demonstrated a 3-fold increase in expression of CYP3A4 protein by 20 microM DPC 681 in primary cultures of human hepatocytes. Subsequent studies showed that DPC 681 was a potent inhibitor of human CYP3A4 (IC50 = 0.039 microM) and rat CYP3A (IC50 = 1.62 microM). Moreover, DPC 681 was a mechanism-based inactivator of CYP3A4 with KI and kinact of 0.24 microM and 0.22 min-1, respectively. Thus, DPC 681 is both a potent inhibitor and a strong inducer of CYP3A4. Induction of CYP3A4 by DPC 681 was masked in vitro by autoinactivation, similar to the protease inhibitor ritonavir. In pharmacokinetic studies in healthy human volunteers and rats, DPC 681 was found to highly autoinduce its metabolism. Human volunteers dosed with DPC 681 at 600 mg twice daily for 14 days had a 75% decrease in the mean area under the concentration-time curve and a more than 3-fold increase in apparent clearance as compared with that on day 1. Because the primary route of DPC 681 clearance is via CYP3A metabolism, the increased clearance observed in clinical studies is due to induction of human CYP3A4 expression.
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PMID:Concurrent induction and mechanism-based inactivation of CYP3A4 by an L-valinamide derivative. 1292 Jan 73