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PubMed2002

Resistance mutations in HIV-infected patients experiencing early failure with nelfinavir-containing triple combinations.

BACKGROUND: The purpose of our study was to assess the presence of nelfinavir (NFV)-associated resistance mutations at the time of early virological failure in subjects receiving NFV as part of a first protease inhibitor (PI)-based triple regimen. MATERIAL/METHODS: Subjects failing their first PI-based NFV-containing triple regimen were identified in six Spanish hospitals. HIV genotyping was carried out in plasma samples collected at the time of the first viral rebound. RESULTS: Upon initiation of NFV-based therapy, 19 of the 30 subjects (63%) were naïve; 11 (37%) had been exposed to nucleoside analogues. Median HIV-RNA at the time of viral rebound was 4, 180 copies/ml. PCR-amplified products were obtained in 22 subjects (73%). These products were sequenced and primary PI resistance mutations were recognized in 6 patients (27%). All six individuals harbored the D30N mutation, and none presented the L90M mutation. Other PI resistance mutations were present in 5 subjects (at codons 36, 63, 71, 77, 82 and/or 88). Secondary PI resistance mutations were present in another 9 subjects. By contrast, mutations conferring resistance to reverse transcriptase inhibitors were present in 50% of the patients, and the M184V substitution was the most frequently seen. CONCLUSIONS: Nearly 75% of patients failing their first PI-based triple regimen containing NFV do not harbor PI resistance mutations. The D30N substitution, rather than L90M, is the most frequently recognized, which does not challenge the efficacy of further rescue interventions with other PIs. This observation supports the use of nelfinavir as first protease inhibitor.

Adult↗
PubMed2005

The HIV protease inhibitors nelfinavir and saquinavir, but not a variety of HIV reverse transcriptase inhibitors, adversely affect human proteasome function.

BACKGROUND: In HIV-infected patients some clinical and immunological benefits of antiretroviral therapy, which frequently include a combination of HIV protease inhibitors (PIs) and reverse transcriptase inhibitors (RTIs), cannot be solely explained by the drugs' action on viral enzymes. Proteasomes constitute the central protease of the ubiquitin ATP-dependent pathway involved in many cellular processes, as well as in HIV maturation and aggressiveness. OBJECTIVE: To explore whether the PIs nelfinavir and saquinavir and the RTIs abacavir, nevirapine, delavirdine, stavudine and didanosine affect proteasome function in vitro and in vivo. METHODS: Peptidase activity of purified human 26S and 20S proteasomes was assayed with and without the drugs at different concentrations. Intracellular proteasome proteolytic activity was evaluated by searching for ubiquitin-tagged proteins in HL60 cells incubated with and without the drugs. RESULTS: At therapeutic dosages, nelfinavir and saquinavir inhibited proteasome peptidase activity and caused intracellular accumulation of polyubiquitinated proteins, a hallmark of proteasome proteolytic inhibition in vivo; the RTIs failed to evoke either effect. CONCLUSION: Proteasomes are targeted by the two PIs but not the RTIs. Therefore, in HIV-infected patients the beneficial effect of a therapy including one of the two PIs should partly rely on inhibition of host proteasome function.

HIV Protease Inhibitors↗
PubMed2005

Amprenavir and efavirenz pharmacokinetics before and after the addition of nelfinavir, indinavir, ritonavir, or saquinavir in seronegative individuals.

Adult AIDS Clinical Trials Group 5043 examined pharmacokinetic (PK) interactions between amprenavir (APV) and efavirenz (EFV) both by themselves and when nelfinavir (NFV), indinavir (IDV), ritonavir (RTV), or saquinavir (SQV) is added. A PK study was conducted after the administration of single doses of APV (day 0). Subjects (n = 56) received 600 mg of EFV every 24 h (q24h) for 10 days and restarted APV with EFV for days 11 to 13 with a PK study on day 14. A second protease inhibitor (PI) (NFV, 1,250 mg, q12h; IDV, 1,200 mg, q12h; RTV, 100 mg, q12h; or SQV, 1,600 mg, q12h) was added to APV and EFV on day 15, and a PK study was conducted on day 21. Controls continued APV and EFV without a second PI. Among subjects, the APV areas under the curve (AUCs) on days 0, 14, and 21 were compared using the Wilcoxon signed-rank test. Ninety-percent confidence intervals around the geometric mean ratios (GMR) were calculated. APV AUCs were 46% to 61% lower (median percentage of AUC) with EFV (day 14 versus day 0; P values of <0.05). In the NFV, IDV, and RTV groups, day 21 APV AUCs with EFV were higher than AUCs for EFV alone. Ninety-percent confidence intervals around the GMR were 3.5 to 5.3 for NFV (P < 0.001), 2.8 to 4.5 for IDV (P < 0.001), and 7.8 to 11.5 for RTV (P = 0.004). Saquinavir modestly increased the APV AUCs (GMR, 1.0 to 1.4; P = 0.106). Control group AUCs were lower on day 21 compared to those on day 14 (GMR, 0.7 to 1.0; P = 0.042). African-American non-Hispanics had higher day 14 efavirenz AUCs than white non-Hispanics. We conclude that EFV lowered APV AUCs, but nelfinavir, indinavir, or ritonavir compensated for EFV induction.

Adolescent↗
PubMed2005

HIV-1 genotype resistance pattern and evolution in patients failing nelfinavir-containing regimens.

Clinical and in vitro studies have suggested that nelfinavir (NFV)-containing regimens may not preclude the use of other protease inhibitors (PIs) in treatment sequencing. We have studied the prevalence of 30N mutation in a human immunodeficiency virus-1 (HIV-1)-infected cohort and the virological response to a PI-containing regimen in patients who had previously failed NFV. A total of 335 patients were included in the study; 32 of them were antiretroviral-naive and 303 were antiretroviral-experienced (251 were PI-experienced). Mutations 30N and/or 90M were not detected in sequences obtained either from the antiretroviral naive or non-PI-experienced patients. The 30N mutation was detected in 21/251 (8.3%) of PI-experienced patients and 90M in 103/251 (41%). Moreover, we have observed that the 88D and 77I mutations were present in more than 75% of patients harbouring the 30N HIV-1 variant and the 71T mutation was present in almost 50% of them. Finally, mutations 30N+90M were never detected together in the same HIV-1 strain. The 30N and 90M mutations were not observed together. The presence of mutations at positions 36, 46, 71, 77, and/or 88 in a 30N background, increases the risk of the cross-resistance to other PIs. The use of NFV as a first-line PI, as an application of drug sequencing strategies, may help preserve future PI options.

Acquired Immunodeficiency Syndrome↗
PubMed2005

Diverse pattern of protease inhibitor resistance mutations in HIV-1 infected patients failing nelfinavir.

The aim of the study was to describe the pattern of resistance mutations in human immunodeficiency virus type 1 (HIV-1) infected patients experiencing their first protease inhibitor (PI) failure on nelfinavir (NFV)-containing therapy. Earlier PI-naïve patients (n=172) with NFV-containing therapy were therefore retrospectively studied. Plasma HIV RNA from 43 failing patients was sequenced. In addition, virus from the baseline was sequenced in 29 patients. Failure was defined as two consecutive measurements of viral load of >50 copies/ml after 6 months treatment. Subtyping was done in most patients (n=118). At baseline, the V82A mutation was found in four PI-naïve patients of whom two failed therapy exhibiting this mutation. At therapy failure, 17 of the 43 (40%) patients had primary PI mutations. In nine subjects, RTI-mutations only were found and 17 patients had a wild-type virus. Patients with primary PI and/or RTI mutations had a higher viral load at failure than those who failed with wild-type virus. A surprisingly diverse pattern of primary PI mutations was seen: M46I (n=7), D30N (n=6), L90M (n=5), and V82A (n=4). Four patients exhibited more than one primary PI mutation. PI-naïve patients in Sweden may harbor PI-resistant virus and resistance testing should be considered before treatment. Patients who fail NFV may develop the M46I mutation, which has been related earlier to mainly other PI. The diverse pattern of the evolved PI-mutations and the relative low occurrence of the D30N mutation in the material was unexpected and did not seem to be related to the viral subtype.

Adolescent↗
PubMed2006

Evaluation of an International Pharmacopoeia method for the analysis of nelfinavir mesilate by liquid chromatography.

A gradient LC method for the determination of related substances in nelfinavir mesilate (NFVM) has been recently published in the International Pharmacopoeia. The method uses a base deactivated reversed phase C18 column (25 cm x 4.6 mm I.D.), 5 microm kept at a temperature of 35 degrees C. The mobile phases consist of acetonitrile, methanol, phosphate buffer pH 3.4 and water. The flow rate is 1.0 ml/min. UV detection is performed at 225 nm. A system suitability test (SST) is described to govern the quality of the separation. The separation towards NFVM components was investigated on 18 C18 columns and correlation was made with the column classification system developed in our laboratory. The method was evaluated using a Hypersil BDS C18 column (25 cm x 4.6 mm I.D.), 5 microm. A two level fractional factorial design was applied to examine the robustness of the method. The method shows good selectivity, precision, linearity and sensitivity. Seven commercial samples were examined using this method.

Chromatography, Liquid↗
PubMed2004

Subnanogram on-line column-switching liquid chromatographic-tandem mass spectrometric quantification method for nelfinavir and methoxyphenol metabolite M1 in rat plasma.

A new on-line, rapid and sensitive column-switch LC/MS/MS method to measure nelfinavir (NFV), an HIV-1 protease inhibitor, and its major metabolite (M1) in rat plasma was developed. Rat plasma containing the analytes and the internal standard was treated with acetonitrile and the supernatant was processed through an on-line extraction and an analytical columns, with a column-switch device. ESI-LC/MS with multiple reaction monitors for appropriate analytes was performed. This assay gave a limit of quantitation (LOQ) of <1 ng/mL for the analytes with 5 min run time. The within-run and between-run precisions were <12 and <10%, respectively. This analytical method was successfully applied to a study to correlate changes in maternal and placental NFV plasma concentrations in rats following NFV exposure in utero.

Animals↗
PubMed2001

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

A reversed-phase high-performance liquid chromatographic method for the simultaneous quantitative determination of five HIV protease inhibitors (i.e. indinavir, amprenavir, saquinavir, ritonavir and nelfinavir) in human plasma is described. An aliquot of 500 microl plasma was extracted with 0.5 ml of 0.1 M NH4OH and 5 ml of methyl tert.-butyl ether. After evaporating, the residue was dissolved in eluent mixture of acetonitrile and 50 mM KH2PO4 adjusted to pH 5.6 with 50 mM Na2HPO4 (43:57, v/v). Subsequently, the eluent was washed with hexane. Chromatography was performed using a C18 reversed-phase column. Ultraviolet detection at 215 nm was used. Linearity of the method was obtained in the concentration range of 0.05-20 microg ml(-1) for all five protease inhibitors. Our method is now in use to analyse plasma samples from patients treated with co-administration of HIV protease inhibitors.

Adult↗
PubMed2001

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.

Carbamates↗
PubMed1999

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

A sensitive high-performance liquid chromatographic method has been developed for the simultaneous determination of the four licensed HIV-protease inhibitors indinavir, nelfinavir, saquinavir and ritonavir. An aliquot of 500 microl plasma, spiked with internal standard, was extracted with 0.5 ml 0.1 M NH4OH and 5 ml methyl tert.-butyl ether. After evaporating, the residue was dissolved in eluent consisting of acetonitrile-50 mM phosphate buffer, pH 5.63 (40:60, v/v). Subsequently, the eluent was washed with hexane. Chromatography was performed using a C18 reversed-phase column and gradient elution with a linear increase of acetonitrile from 36 to 66%. Ultraviolet detection at 215 nm was used. Linearity of the method was obtained in the concentration range of 45-30 000 ng/ml for all four analytes. The method was validated extensively and stability tests under various conditions were performed. The assay is now in use to analyse plasma samples from patients treated with (combinations of) HIV-protease inhibitors.

Anti-HIV Agents↗
PubMed1999

Determination of nelfinavir, a potent HIV protease inhibitor, and its active metabolite M8 in human plasma by high-performance liquid chromatography with photodiode-array detection.

We developed and characterized a high-performance liquid chromatographic assay for the determination of nelfinavir (NFV), a potent HIV protease inhibitor, and its active metabolite M8 in human plasma. Extraction of the internal standard, M8 and NFV from the plasma buffered at pH 9.5 was achieved by a liquid-liquid extraction with a mixture of methyl-tert.-butyl ether and hexane. Following two washes of the reconstituted sample with hexane, separation was achieved on an octadecylsilyl analytical column with a mobile phase containing 0.1% trifluoroacetic acid-acetonitrile-methanol (51:46:5, v/v). Detection was performed using an ultraviolet photodiode-array detector. The signal was monitored at a wavelength of 220 nm. The assay was found to be linear and has been validated over the concentration range of 25 to 3000 microg/l for M8 and 25 to 6000 microg/l for NFV, from 500 microl of plasma. Recoveries were 98.9% (SD 8.9%), and 100.2% (SD 11.7%) for M8 and NFV, respectively. Concentrations that gave a signal-to-noise ratio of three (15 microg/l for both M8 and NFV) were selected to determine the limit of detection. The lower limit of quantification (25 microg/l for both M8 and NFV) was defined as the concentration for which the relative standard deviation and the percent deviation from the nominal concentration were lower than 20%.

Anti-HIV Agents↗
PubMed2002

Simultaneous determination of five HIV protease inhibitors nelfinavir, indinavir, ritonavir, saquinavir and amprenavir in human plasma by LC/MS/MS.

A sensitive and rapid liquid chromatography tandem mass spectrometry (LC-MS-MS) method has been developed to measure the levels of five HIV protease inhibitors nelfinavir (NFV), indinavir (IDV), ritonavir (RTV), saquinavir (SQV) and amprenavir (APV) in human plasma. The analytes and internal standard are isolated from plasma by a simple acetonitrile precipitation of plasma proteins followed by centrifugation. LC-MS-MS in positive mode used pairs of ions at m/z of 568.4/330.0, 614.3/421.2, 720.9/296.0, 671.1/570.2 and 505.9/245.0 for NFV, IDV, RTV, SQV and APV, respectively and 628/421 for the internal standard. Two 1/x weighted linear calibration curves for each analyte were established for quantitation with the low curve ranging from 5 to 1000 ng/ml and while the high curve ranging from 1000 to 10,000 ng/ml. Mean inter- and intra-assay coefficients of variation (CVs) over the ranges of the standard curves were less than 10%. The overall recovery of NFV, IDV, RTV, SQV and APV were 88.4, 91.4, 92.2, 88.9 and 87.6%, respectively.

Carbamates↗
PubMed2001

Limits of deep salvage antiretroviral therapy with nelfinavir plus either efavirenz or nevirapine, in highly pre-treated patients with HIV disease.

The virological and immunological response to an efavirenz-containing rescue regimen was compared with that of a nevirapine-containing one in a prospective, open-label 12-month study performed in patients previously treated with > or = 12 months of nucleoside analogue monotherapy, and > or = 15 months of indinavir- or ritonavir-containing HAART. Pooled laboratory data were assessed according to change or continuation of nucleoside analogues, at the time of start of salvage treatment. An improvement of markers of HIV disease progression occurred in all 59 evaluable patients (with a higher viral load decrease in the efavirenz over the nevirapine group at the third month), but the virological response was neither complete nor sustained at the end of study, irrespective of efavirenz or nevirapine adjunct, and complete viral suppression was attained in only 16.9% of subjects. A progressively increasing mean CD4+ lymphocyte count characterized the immunological response of all patients. The 35 patients who changed at least one nucleoside analogue when introducing salvage therapy had a better outcome, irrespective of the non-nucleoside reverse transcriptase inhibitor chosen. Rescue strategies are increasingly needed in HIV-infected patients treated for a long time with HAART. The association of nelfinavir, a non-nucleoside reverse transcriptase inhibitor, and dual nucleoside analogues, is popular among patients who fail first-line HAART. When prolonged prior treatment with nucleoside analogue monotherapy and HAART are of concern, and a quite elevated viral load is present, this salvage regimen may not allow a complete and sustained virological response in a 1-year period, while a more favourable immunological recovery can be expected. However, the concurrent change of nucleoside analogues significantly improves treatment outcome.

Adult↗
PubMed2003

Primary nelfinavir (NFV)-associated resistance mutations during a follow-up period of 108 weeks in protease inhibitor naïve patients treated with NFV-containing regimens in an HIV clinic cohort.

BACKGROUND: Nelfinavir (NFV) is a widely prescribed HIV-1 specific protease inhibitor (PI). However, there are only a few reports that have described the long-term effects of NFV-containing regimens, especially with regard to the emergence of drug resistance in inner-city clinics. OBJECTIVES: The aim of this study was to investigate the clinical and virologic responses to treatment with NFV-containing regimens for up to 108 weeks and determine the timing and rate of emergence of primary NFV-resistance associated mutations in daily clinical practice. STUDY DESIGN: A cohort study in an inner-city clinic. Our study included 51 consecutive patients who were PI-nai;ve and commenced therapy in February 1997 through April 1999. RESULTS AND CONCLUSIONS: The proportions of patients who continued the same therapeutic regimen and showed virologic success (viral load <400 copies/ml) up to 108 weeks were 78 and 63%, respectively, based on intent-to-treat analysis. Among patients with a viral load persistently >400 copies/ml at week 12 (n=30), 11 developed primary NFV-resistance associated mutations by 108 weeks (stratified log-rank test; P<0.05). The Cox proportional hazard model showed that prior use of reverse transcriptase inhibitors (n=22) (relative hazard (RH); 2.10, 95% CI; 0.67-6.62), prior AIDS diagnosis (n=6) (RH; 1.70, 95% CI; 0.37-7.77), CD4 < 200/microl at baseline (n=19) (RH; 2.48, 95% CI; 0.78-7.81) and viral load >30,000 copies/ml at baseline (n=21) (RH; 2.10, 95% CI; 0.67-6.62) were not independent predictors of the NFV-resistance, although some tendency was noted. In total, 77% of the patients continued NFV-containing treatment without the NFV-resistance for 108 weeks. The viral load at week 12 could be used as a predictor of treatment success in our cohort study.

Adult↗
PubMed1997

Viracept (nelfinavir mesylate, AG1343): a potent, orally bioavailable inhibitor of HIV-1 protease.

Using a combination of iterative structure-based design and an analysis of oral pharmacokinetics and antiviral activity, AG1343 (Viracept, nelfinavir mesylate), a nonpeptidic inhibitor of HIV-1 protease, was identified. AG1343 is a potent enzyme inhibitor (Ki = 2 nM) and antiviral agent (HIV-1 ED50 = 14 nM). An X-ray cocrystal structure of the enzyme-AG1343 complex reveals how the novel thiophenyl ether and phenol-amide substituents of the inhibitor interact with the S1 and S2 subsites of HIV-1 protease, respectively. In vivo studies indicate that AG1343 is well absorbed orally in a variety of species and possesses favorable pharmacokinetic properties in humans. AG1343 (Viracept) has recently been approved for marketing for the treatment of AIDS.

Administration, Oral↗
PubMed2000

(1S)-1-[(4R)-2,2-dimethyl-1,3-dioxolan+-4-yl][-2-hydroxyethylamm onium benzoate, a versatile building block for chiral 2-aminoalkanols: concise synthesis and application to nelfinavir, a potent HIV-protease inhibitor.

A concise synthesis of a versatile chiral C4 building block for 2-aminoalkanols, (1S)-1-[(4R)-2,2-dimethyl-1,3-dioxolan-4-yl]-2-hydroxyethylammo nium benzoate (1a), was described. 1 (1a and its enantiomer 1b) acted as four stereoisomers of optically active 2-amino-1,3,4-butanetriol. The versatility of 1 was demonstrated by its application to the practical synthesis of nelfinavir (2), a potent HIV-protease inhibitor, as well as by the stereospecific synthesis of three diastereomers of 2.

Amino Alcohols↗
PubMed2005

Resistant mechanism against nelfinavir of human immunodeficiency virus type 1 proteases.

Inhibitors against human immunodeficiency virus type-1 (HIV-1) proteases are finely effective for anti-HIV-1 treatments. However, the therapeutic efficacy is reduced by the rapid emergence of inhibitor-resistant variants of the protease. Among patients who failed in the inhibitor nelfinavir (NFV) treatment, D30N, N88D, and L90M mutations of HIV-1 protease are often observed. Despite the serious clinical problem, it is not clear how these mutations, especially nonactive site mutations N88D and L90M, affect the affinity of NFV or why they cause the resistance to NFV. In this study, we executed molecular dynamics simulations of the NFV-bound proteases in the wild-type and D30N, N88D, D30N/N88D, and L90M mutants. Our simulations clarified the conformational change at the active site of the protease and the change of the affinity with NFV for all of these mutations, even though the 88th and 90th residues are not located in the NFV-bound cavity and not able to directly interact with NFV. D30N mutation causes the disappearance of the hydrogen bond between the m-phenol group of NFV and the 30th residue. N88D mutation alters the active site conformation slightly and induces a favorable hydrophobic contact. L90M mutation dramatically changes the conformation at the flap region and leads to an unfavorable distortion of the binding pocket of the protease, although 90M is largely far apart from the flap region. Furthermore, the changes of binding energies of the mutants from the wild-type protease are shown to be correlated with the mutant resistivity previously reported by the phenotypic experiments.

Drug Resistance, Viral↗
PubMed2002

Transepithelial transport of prodrugs of the HIV protease inhibitors saquinavir, indinavir, and nelfinavir across Caco-2 cell monolayers.

PURPOSE: [corrected] This study is dedicated to the permeation of various amino acid-, D-glucose-, and PEG-conjugates of indinavir, saquinavir, and nelfinavir across monolayers of Caco-2 cells as models of the intestinal barrier. This screening is aimed at detecting the most promising prodrugs for improving the intestinal absorption of these protease inhibitors. METHODS: The bidirectional transport of the prodrugs was investigated using P-gp-expressing Caco-2 monolayers grown on membrane inserts using high-performance liquid chromatography for quantitation. RESULTS: The L-valyl, L-leucyl, and L-phenylalanyl ester conjugates led to an enhancement of the absorptive flux of indinavir or saquinavir. These results are likely attributable to an active transport mechanism and/or to a decrease of their efflux by carriers such as P-gp. Connection of tyrosine through its hydroxyl, of D-glucose, or of polyethylene glycol decreased their absorptive and secretory diffusion. CONCLUSIONS: Conjugation of the protease inhibitors to amino acids constitutes a most appealing alternative that could improve their intestinal absorption and oral bioavailability. Whether it could improve their delivery into the central nervous system remains to be explored. D-Glucose conjugation will most probably not improve their intestinal absorption or their crossing of the blood-brain barrier. If some pharmacologic benefits are to be expected from PEG-protease inhibitor conjugates, they must then be administered intravenously.

Biological Transport↗