Delavirdine mesylate – also known under the code PF-00596729 and the development name U-90152S – is a potent non-nucleoside reverse transcriptase inhibitor (NNRTI) of HIV-1, first described in 1993 and later approved as Rescriptor. The Delavirdine mesylate molecular weight is 552.68 g/mol. The Delavirdine mesylate molecular structure is based on a bisheteroarylpiperazine scaffold: an indole-2-carbonyl group linked via a piperazine to a 2-aminopyridine with a methanesulfonamide on the indole ring. The mesylate salt form (CAS 147221-93-0) is the standard research-grade formulation, freely soluble in DMSO.
Application of Delavirdine mesylate
The primary research applications center on HIV-1 reverse transcriptase biology, NNRTI resistance mechanisms, and CYP3A-mediated drug interaction studies. Unlike nevirapine and efavirenz – which induce CYP enzymes – Delavirdine mesylate inhibits CYP3A4, giving it a distinct pharmacokinetic interaction profile studied in combination antiretroviral research. The Delavirdine mesylate structure also serves as a scaffold reference for medicinal chemistry programs developing next-generation NNRTIs with improved resistance profiles.
In Vitro
Delavirdine mesylate selectively inhibits HIV-1 reverse transcriptase over other cellular polymerases, with IC50 values of 0.26 μM for HIV-1 RT, 440 μM for DNA polymerase α, and >550 μM for DNA polymerase δ – a >1000-fold selectivity window that makes the compound suitable as a research tool without confounding cytotoxic effects. In peripheral blood lymphocytes, it blocked replication of 25 primary HIV-1 isolates – including AZT- and ddI-resistant variants – with a mean ED50 of 0.066 μM, while causing less than 8% reduction in lymphocyte viability at 100 μM.
In Vivo
In HIV-1-infected patients, hepatic CYP3A activity was markedly reduced after exposure at all tested doses; delavirdine mesylate could maximally inhibit 70–75% of baseline CYP3A values with an IC50 of approximately 0.9 μmol/L. This inhibition is reversible – activity returns to baseline within one week after discontinuation – a pharmacodynamic property relevant when modeling drug washout in combination regimen studies.
Biochemical and Physiological Actions
Delavirdine binds directly to reverse transcriptase and blocks both RNA-dependent and DNA-dependent DNA polymerase activities without competing with template:primer or deoxynucleoside triphosphates. This non-competitive binding mode explains why resistance mutations in the NNRTI binding pocket are the primary escape route. The Delavirdine mesylate chemical structure engages a hydrophobic pocket adjacent to the RT catalytic center, inducing a conformational change that restricts polymerase mobility. In vitro and in vivo data show that delavirdine also reduces CYP2C9, CYP2D6, and CYP2C19 activity and inhibits its own metabolism, producing nonlinear steady-state kinetics.
Features and Benefits of Delavirdine mesylate
Delavirdine mesylate occupies a specific niche among NNRTI reference compounds: it combines a characterized RT inhibition profile with documented CYP3A inhibitory activity absent in other approved NNRTIs. For researchers studying NNRTI-RT interactions, resistance profiling against nucleoside-resistant isolates, or CYP-mediated pharmacokinetic drug interactions in antiretroviral combinations, the compound provides a cross-validated dataset spanning biochemical assays, primary cell models, and clinical PK studies.
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