Rapid quantification of delavirdine, a novel non-nucleoside reverse transcriptase inhibitor, in human plasma using isocratic reversed-phase high-performance liquid chromatography with fluorescence detection

Simple and rapid quantification of the non-nucleoside reverse transcriptase inhibitors nevirapine, delavirdine, and efavirenz in human blood plasma using high-performance liquid chromatography with ultraviolet absorbance detection

A simple reversed-phase high-performance liquid chromatography assay for the simultaneous quantitative determination of three HIV non-nucleoside reverse transcriptase inhibitors (nevirapine, delavirdine, and efavirenz) in human blood plasma is described. The method was validated over the range of 10 ng/ml to 50 microg/ml for nevirapine, 25 ng/ml to 25 microg/ml for delavirdine, and 10 ng/ml to 10 microg/ml for efavirenz. The method is accurate (average accuracies over eight concentrations ranging from 87.3 to 113%), and precise (within-day and between-day precision measures ranging from 0.12 to 7.9% and 0.26 to 5.9%, respectively). All three non-nucleoside reverse transcriptase inhibitors proved to be stable under various conditions. Due to its simplicity, this assay can readily be used for investigational or clinical monitoring of plasma concentrations.

Determination of delavirdine in very small volumes of plasma by high-performance liquid chromatography with fluorescence detection

Delavirdine is a newly developed anti-HIV-1 drug for AIDS therapy. This study describes a sensitive high-performance liquid chromatographic method for the determination of delavirdine in 50 microl of plasma. Samples were deproteinized with 150 microl of a solution of internal standard (cisapride 10 microg/ml) in acetonitrile. An aliquot of the supernatant was injected onto the column. HPLC separation was achieved on a C18 column with the mobile phase of acetonitrile-50 mM sodium dihydrogen phosphate (60:40, v/v) at a flow-rate of 1 ml/min. The eluants were measured by fluorescence detection with excitation at 295 nm and emission filtration at 425 nm. The retention time was about 5.3 min for delavirdine and 6.5 min for cisapride. The specificity was demonstrated, as there were no interferences from plasma samples of different batches in the regions of peak interest. Calibration curves were linear from 25 to 25000 ng/ml. The limit of quantitation was 25 ng/ml. The within- and between-day precision (C.V.) was 9.3%, or less, and the accuracy was within 9.2% of the nominal concentration. The small sample volume needed is especially advantageous for the application both in pharmacokinetic studies in HIV-infected adults and pediatric patients, and in small animals, where limited samples are available.

Simultaneous determination of the HIV-protease inhibitors indinavir, amprenavir, ritonavir, saquinavir and nelfinavir in human plasma by reversed-phase high-performance liquid chromatography

A rapid, simple and sensitive high-performance liquid chromatographic (HPLC) assay has been developed for the simultaneous quantification of the HIV-protease inhibitors indinavir, amprenavir, ritonavir, saquinavir and nelfinavir in human plasma. The method involved the solid-phase extraction of the five drugs and the internal standard (I.S., verapamil) from 400 microl of human plasma. The HPLC analysis used a reversed-phase C18 analytical column and a mobile phase consisting of a gradient with 15 mM phosphate buffer (pH 5.75)-acetonitrile and UV monitoring. The method was linear over the therapeutic concentration range for the five HIV-protease inhibitors. The accuracy of the method ranged from 98.2 to 106.7% and the precision values ranged from 1.4 to 8.1% for intra-day precision and from 3.1 to 6.4% for the inter-day values.

High-performance liquid chromatographic method for the determination of HIV-1 non-nucleoside reverse transcriptase inhibitor efavirenz in plasma of patients during highly active antiretroviral therapy

A new high-performance liquid chromatographic method for the determination of efavirenz in human plasma is described. Quantitative recovery following liquid-liquid extraction with diethylether from 200 microl of human plasma was achieved. Subsequently, the assay was performed with 67 mM potassium dihydrogen phosphate-acetonitrile as a mobile phase, a XTerraRP 18 column protected with a Phenomenex C18 column and UV detection at 246 nm. Linear standard curves were obtained for concentrations ranging from 25 to 15,000 ng/ml. The calculated intra- and inter-day coefficients of variation were below 10%.

Delavirdine: a review of its use in HIV infection

Delavirdine, a bisheteroarylpiperazine derivative, is a non-nucleoside reverse transcriptase inhibitor (NNRTI) that allosterically binds to HIV-1 reverse transcriptase, inhibiting both the RNA- and DNA-directed DNA polymerase functions of the enzyme. Delavirdine in combination with nucleoside reverse transcriptase inhibitors (NRTIs) produced sustained reductions in plasma viral loads and improvements in immunological responses in large randomised, double-blind, placebo-controlled studies of 48 to 54 weeks' duration. In patients with advanced HIV infection, triple therapy with delavirdine, zidovudine and lamivudine, didanosine or zalcitabine for 1 year significantly prolonged the time to virological failure compared with dual therapy (delavirdine plus zidovudine or 2 NRTIs; p < 0.0001). After 50 weeks' treatment, plasma HIV RNA levels were below the limit of detection (LOD; <50 copies/ml) for 40% of patients receiving triple therapy but for only 6% of those receiving dual NRTI therapy. Preliminary results suggest that delavirdine also has beneficial effects on surrogate markers as a component of protease inhibitor-containing triple or quadruple regimens. At 16 to 48 weeks, the minimum mean reduction in plasma viral load from baseline was 2.5 log10 copies/ml and mean CD4+ counts increased by 100 to 313 cells/microl. The proportion of patients with plasma HIV RNAlevels below the LOD (usually 200 to 500 copies/ml) ranged from 48 to 100% after > or = 16 weeks. Delavirdine was also effective as a component of saquinavir soft gel capsule-containing salvage regimens. Since delavirdine shares a common metabolic pathway (cytochrome P450 3A pathway) with other NNRTIs, HIV protease inhibitors and several drugs used to treat opportunistic infections in patients infected with HIV, the drug is associated with a number of pharmacokinetic interactions. Some of these drug interactions are clinically significant, necessitating dosage adjustments or avoidance of co-administration. Delavirdine is not recommended for use with lovastatin, simvastatin, rifabutin, rifampicin, sildenafil, ergot derivatives, quinidine, midazolam, carbamazepine, phenobarbital or phenytoin. Importantly, the drug favourably increases the plasma concentration of several protease inhibitors. Delavirdine is generally well tolerated. Skin rash is the most frequently reported adverse effect, occurring in 18 to 50% of patients receiving delavirdine-containing combination therapy in clinical trials. Although a high proportion of patients developed a rash, it was typically mild to moderate in intensity, did not result in discontinuation or adjustment of treatment in most patients and resolved quickly. The occurrence of Stevens-Johnson syndrome was rare (1 case in 1,000 patients). A retrospective analysis of pooled clinical trial data indicated that there was no significant difference in the incidence of liver toxicity, liver failure or noninfectious hepatitis between delavirdine-containing and non-delavirdine-containing antiretroviral treatment groups. In addition, the incidence of lipodystrophy, metabolic lipid disorders, hyperglycaemia and hypertriglyceridaemia was not significantly different between these 2 treatment groups.

CONCLUSIONS

In combination with NRTIs. delavirdine produces sustained improvements in surrogate markers of HIV disease and prolongs the time to virological failure in adult patients with HIV infection. Preliminary data of delavirdine as a component of protease inhibitor-containing triple or quadruple highly active antiretroviral therapy regimens indicate that patients achieve marked improvements in virological and immunological markers. The drug is generally well tolerated, with a transient skin rash, typically of mild to moderate intensity, being the most common adverse effect. Delavirdine is an effective component of recommended antiretroviral treatment strategies for adult patients with HIV infection and, in combination with 2 NRTIs as a first-line therapy, the drug has the advantage of sparing protease inhibitors for subsequent use. Since delavirdine favourably increases plasma concentrations of several protease inhibitors, the drug may also be beneficial as a component of salvage therapy in combination with protease inhibitors.

Determination of twelve antiretroviral agents in human plasma sample using reversed-phase high-performance liquid chromatography

A new high-performance liquid chromatography (HPLC) with UV detection assay was developed for the simultaneous determination of protease inhibitors (PIs), nucleoside and non-nucleoside reverse transcriptase inhibitors (NRTIs, NNRTIs) using a single 1-ml plasma samples. A solid-liquid extraction procedure without internal standard was coupled with two separate reversed-phase HPLC systems; one for the determination of amprenavir, efavirenz, indinavir, nelfinavir, ritonavir, saquinavir (run time=32 min) and one for the determination of abacavir, didanosine, lamivudine, stavudine, nevirapine, zidovudine (run time=40 min). The first requires a mobile phase containing sodium phosphate buffer+ion pair-acetonitrile (50:50, v/v) through a C18 Symmetry column (250x4.6 mm I.D., 5 microm particle size), using variable wavelengths (241, 254 and 261 nm). The second system requires three mobile phases (potassium phosphate buffer+ion pair-acetonitrile) for different elution through a C18 Symmetry Shield column (250x4.6 mm I.D., 5 microm), using a single wavelength (260 nm). Peak-areas are linear; correlation coefficients are better than 0.998 for all compounds, with both inter- and intra-day relative standard deviations lower than 12%. Extraction recoveries are higher than 93% for PIs and NNRTIs and higher than 70% for NRTIs. The method is specific and sensitive and was used to determine trough and peak levels of antiretroviral drugs in HIV infected patients under various combinations of RTIs and PIs.

Simultaneous high-performance liquid chromatographic determination of the antiretroviral agents amprenavir, nelfinavir, ritonavir, saquinavir, delavirdine and efavirenz in human plasma

This article describes a method for the simultaneous determination of four licensed HIV protease inhibitors (amprenavir, nelfinavir, saquinavir and ritonavir) and two novel non-nucleoside reverse transcriptase inhibitors (efavirenz and delavirdine) in human plasma in a single run. Plasma samples (500 microl) were treated by liquid-liquid extraction with methyl tert.-butyl ether. The compounds were separated by reversed-phase liquid chromatography on a C(18) column with spectrophotometric detection at 260 nm. The method is linear over the specific ranges investigated, accurate (inaccuracy <11.7%) and showed intra-day and inter-day precision within the ranges of 0.9-7.0 and 1.9-8.8%, respectively. The six compounds were stable in plasma after 6 months of storage at -20 degrees C and after five freeze-thaw cycles.