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Pharmacokinetics of indinavir and nelfinavir in treatment-naive, human immunodeficiency virus-infected subjects.

AIDS Clinical Trials Group protocol 388 was designed to compare a three-drug regimen (indinavir with dual nucleosides) to a four-drug regimen (indinavir plus nelfinavir or indinavir plus efavirenz with dual nucleosides). Blood samples from patients taking indinavir and nelfinavir were collected over 8 to 12 h following a specified dose and were analyzed with high-performance liquid chromatography. Pharmacokinetic data were derived by using noncompartmental analysis. Following administration of indinavir every 8 h in the absence of nelfinavir (n = 8), the median predose indinavir concentration (C(0)) was 369 ng/ml (range, <10 to 949 ng/ml; one subject had a concentration of <10 ng/ml), and the concentration 8 h after administration of the study dose was 159 ng/ml (range, 85 to 506 ng/ml). In the group receiving 1000 mg of indinavir every 12 h with nelfinavir (n = 10), the median indinavir C(0) was <10 ng/ml (range, <10 to 3740 ng/ml; six subjects had a value of <10 ng/ml), and the C(12 h) was 44 ng/ml (range, <10 to 4236 ng/ml; five subjects had a value of <10 ng/ml), while the subjects who received 1200 mg of indinavir every 12 h with nelfinavir (n = 7) had a C(0) of 146 ng/ml (range, 58 to 5215 ng/ml) and a C(12 h) of 95 ng/ml (range, 12 to 954 ng/ml). Indinavir clearance was significantly lower in the presence of nelfinavir (median [interquartile range], 34.1 liters/h [range, 22.6 to 45.8 liters/h] versus 47.9 liters/h [range, 42.7 to 70.3 liters/h]; P < 0.017). For subjects receiving 1,000 mg of indinavir every 12 h, the median C(0) value for nelfinavir (n = 9) was 1,779 ng/ml (range, <187.5 to 4579 ng/ml), and the C(12 h) was 1554 ng/ml (range, <187.5 to 5,540 ng/ml). Due to the unacceptable number of undetectable indinavir trough concentrations, 1200 mg of indinavir appears to be the preferred dose in a twice-daily regimen that includes nelfinavir.

Adult↗

Age-related effects on nelfinavir and M8 pharmacokinetics: a population study with 182 children.

As a relationship between nelfinavir antiretroviral efficacy and plasma concentrations has been previously established, nelfinavir pharmacokinetics was investigated in order to optimize the individual treatment schedule in a pediatric population. A population pharmacokinetic model was developed to describe the concentration-time course of nelfinavir and its active metabolite M8. Individual characteristics were used to explain the large interindividual variability in children. Data from therapeutic drug monitoring in 182 children treated with nelfinavir were analyzed with NONMEM. Then Food and Drug Administration (FDA) current recommendations were evaluated estimating the percentage of children who reached the target minimum plasma concentration (0.8 mg/liter) by using Bayesian estimates. Nelfinavir pharmacokinetics was described by a one- compartment model with linear absorption and elimination. Pharmacokinetic estimates and the corresponding intersubject variabilities for the model were as follows: nelfinavir total clearance, 0.93 liters/h/kg (39%); volume of distribution, 6.9 liters/kg (109%); absorption rate, 0.5 h(-1); formation clearance fraction to hydroxy-tert-butylamide (M8), 0.025; M8 elimination rate, 1.88 h(-1) (49%). Apparent nelfinavir total clearance and volume of distribution decreased as a function of age. M8 elimination rate was increased by concomitant administration of nevirapine or efavirenz. Our data confirm that the FDA recommendations for children from 2 to 13 years are optimal and that the dose recommended for children younger than 2 years is adequate for the children from 2 months to 2 years old. However, in children younger than 2 months, the proposed nelfinavir newborn dose of 40 mg/kg of body weight twice daily is inadequate and we suggest increasing the dose to 50 to 60 mg/kg administered thrice daily. This assumption should be further evaluated.

Aging↗

Pharmacokinetics of nelfinavir in subjects with hepatic impairment.

HIV-seronegative subjects with hepatic impairment (6 mild, 6 moderate) and 12 matched healthy controls received nelfinavir 1250 mg every 12 hours with food for 2 weeks. Mild impairment did not significantly change nelfinavir or major metabolite (M8) steady-state exposures compared with controls. In subjects with moderate impairment, steady-state area under the plasma concentration time-curve over the dosing interval and maximum observed plasma concentrations were 62% and 22% higher for nelfinavir than for controls, and for M8 were 46% and 35% of control values. With increasing degree of impairment, no trend toward increase in unbound nelfinavir was observed, but there was an increase in unbound M8 levels. Nelfinavir was safe and well tolerated. One subject with moderate impairment was discontinued because of transient leucopenia. Observed changes are unlikely to affect nelfinavir efficacy or markedly influence safety. Dose reduction of nelfinavir does not appear necessary for subjects with mild/moderate impairment. Further long-term evaluations of nelfinavir pharmacokinetics and safety in HIV-seropositive subjects with hepatic impairment may be useful.

Adult↗

Increase in thyroid follicular cell tumors in nelfinavir-treated rats observed in a 2-year carcinogenicity study is consistent with a rat-specific mechanism of thyroid neoplasia.

The carcinogenic potential of nelfinavir mesylate (nelfinavir) was evaluated in a 2-year oral (gavage) study on Sprague-Dawley rats at dose levels of 0 (control), 0 (vehicle control), 100, 300 and 1000 mg/kg per day. At the end of the treatment, increased incidences of thyroid follicular cell hyperplasia and neoplasms were observed at 300 (males) and 1000 mg/kg per day (both sexes). There were no other treatment-related effects and no tumors at other sites. Results from previous studies indicated a number of effects in the liver and thyroid, as well as metabolic profiles that suggested nelfinavir might cause thyroid hyperplasia/neoplasia secondary to hormone imbalance by altering thyroid hormone disposition. To investigate this hypothesis, the effects of nelfinavir on gene expression in rat hepatocytes and liver slices (in vitro), thyroxine plasma clearance, and thyroid gland function were evaluated. Compared to controls, gene expression analyses demonstrated an increased expression of glucuronyltransferase (UDPGT) and CYP450 3A1 in nelfinavir-treated rat hepatocytes and liver slices. In rats treated with nelfinavir (1000 mg/kg per day) for 4 weeks, liver weights and centrilobular hepatocellular hypertrophy were increased and minimal to mild diffuse thyroid follicular cell hypertrophy and follicular cell hyperplasia were evident in the thyroid gland. Thyroid-stimulating hormone (TSH) levels were significantly increased (three-fold), while tri-iodothyronine (T3)/tetra-iodothyronine (T4) and reverse T3(rT3) levels were unchanged, indicating that a compensated state to maintain homeostasis of T3/T4 had been achieved. Plasma 125I-thyroxine clearance was increased and the plasma thyroxine AUC0-48 was decreased (24%) compared to control. In conclusion, these data indicate that thyroid neoplasms observed in the nelfinavir-treated rats were secondary to thyroid hormone imbalance. Increased thyroxine clearance contributes to the effects of nelfinavir on thyroid gland function and is probably a result of UDPGT induction that leads to elevated TSH levels in the rat and eventual thyroid neoplasia. These results are consistent with a well-recognized rat-specific mechanism for thyroid neoplasms.

Adenocarcinoma, Follicular↗

Virological efficacy and plasma drug concentrations of nelfinavir plus saquinavir as salvage therapy in HIV-infected patients refractory to standard triple therapy.

Therapeutic options are limited for patients refractory to triple therapy with two reverse transcriptase inhibitors and one protease inhibitor. Preliminary results showing favorable effects of protease inhibitor combination therapy with nelfinavir and saquinavir due to inhibition of metabolism by cytochrome P450 (CYP450) prompted us to study this combination. - Thirteen patients with incomplete suppression of plasma HIV-RNA were enrolled and treatment was started with nelfinavir 750 mg tid and saquinavir 400 mg bid. Saquinavir-dosage was escalated in weekly intervals to 400 mg tid and 600 mg tid, respectively. All doses were given with food, and plasma levels of saquinavir and nelfinavir were assessed 4 hours post-dosing after 1, 2, 3, 4 and 8 weeks. Treatment was considered virologically efficacious if HIV-viral load was reduced by at least 0.5 log10 from baseline. - Double protease inhibitor-treatment with nelfinavir and saquinavir was virologically efficacious in 5/13 (39%) patients after 4 weeks but only in 4/13 (31%) patients after 8 and 1/13 (8%) after 16 and 24 weeks, respectively. No statistical difference in plasma concentrations was observed when saquinavir was administered in increasing doses of 400 mg bid, 400 mg tid or 600 mg tid in combination with nelfinavir. 5/13 (39%) patients developed diarrhea (>4/d), no other serious side-effects were observed. By eight weeks, the mean CD4 count for all patients was significantly higher when compared to baseline. - In patients refractory to standard triple therapy the combination of nelfinavir and saquinavir showed significant elevation of CD4-count, but only short term virological efficacy in a minority of patients. Plasma concentrations of saquinavir could not be increased by weekly dose escalation of the drug from 400 mg bid to 600 mg tid. Saquinavir drug concentrations of 600 mg saquinavir tid and nelfinavir showed rather non-significant lower values when compared to historical controls treated with a double-dose 1200 mg saquinavir tid regimen alone. We conclude that in these patients the combination of nelfinavir plus saquinavir has no advantage in terms of increasing bioavailibility of saquinavir or virological efficacy. During short observation time a beneficial effect on CD4-count was observed.

Adult↗

Safety and pharmacokinetics of nelfinavir coadministered with zidovudine and lamivudine in infants during the first 6 weeks of life.

The safety and pharmacokinetics of nelfinavir coadministered with zidovudine and lamivudine were studied in 26 infants during the first 6 weeks of life. Cohort 1 infants (n = 7) received 10 mg/kg 3 times a day, and cohort 2 infants (n = 19) received 40 mg/kg twice a day. Two cohort 1 infants at week 1 and none at week 6 exceeded the target 24-hour area under the curve (AUC) of 30 mug.h/mL, equal to the 10th percentile of the AUC for adults receiving standard nelfinavir dosing. In cohort 2, the median 24-hour AUC was 38 mug.h/mL at both time points, with considerable variability among the infants. Three of 11 cohort 2 infants at week 1 and 4 of 11 at week 6 did not meet the AUC target. Median nelfinavir oral clearance was 2.1 L/h/kg at weeks 1 and 6. The median ratio of the plasma concentrations of the nelfinavir metabolite M8 to unchanged nelfinavir increased from 0.16 (range: 0-0.38) during week 1 to 0.56 (range: 0.4-1.47) during week 6 (P < 0.01). There were no significant differences in any of the other pharmacokinetic parameters when week 1 and week 6 results were compared. Few adverse events were attributed to nelfinavir. These data suggest that nelfinavir is well tolerated in infants at these doses, but exposure was frequently less than that seen in adults taking standard nelfinavir dosing. Further investigations of larger doses, such as 75 mg/kg twice a day, should be undertaken.

Cohort Studies↗

Safety, pharmacokinetics, and antiretroviral activity of the potent, specific human immunodeficiency virus protease inhibitor nelfinavir: results of a phase I/II trial and extended follow-up in patients infected with human immunodeficiency virus.

The safety, antiretroviral activity, and pharmacokinetic profile of nelfinavir, a potent and specific inhibitor of human immunodeficiency virus (HIV) protease, were assessed in a small open-label phase I/II dose-ranging study in protease inhibitor-naive HIV-positive men. A total of 22 patients with baseline plasma HIV RNA > or = 20,000 copies/mL and CD4+ counts between 200 and 500 cells/mm3 were enrolled in the study. Of the 22 patients, 20 were evaluated for activity; 10 patients assigned to 771 mg/day base equivalent (300 mg three times daily) and 10 patients assigned to 1,026 mg/day base equivalent (600 mg twice daily) given monotherapy. A capsule formulation of nelfinavir was used. The initial study period was 28 days; patients showing a virologic response of 1 log10 reduction were eligible for enrollment in an extension phase and addition of nucleoside analogues. A maximally tolerated dose of nelfinavir was not established. A dose-response relationship was observed for four (40%) patients in the 771-mg group and six (60%) patients in the 1,026-mg group experiencing a reduction from baseline in plasma HIV RNA of at lest 1 log during the 28-day study. Of these patients, five sustained the reduction in plasma HIV RNA beyond day 28 (2 patients receiving 771 mg/day and 3 patients receiving 1,026 mg/day). Median increases from baseline in CD4+ counts at day 28 were 216 cell/mm3 and 86 cell/mm3 in the 771-mg and 1,026-mg groups, respectively. After oral administration, median nelfinavir plasma concentrations on day 28 reached a maximum at 1 hour (2,966 ng/mL) in the 771-mg group and at 3 hours (3,157 ng/mL) in the 1,026-mg group. Data for 22 patients were included in the safety analysis; 12 patients (55%) reported at least one grade 2 or worse (moderate, severe, or very severe) adverse event. The most common grade 2 or worse adverse event was diarrhea, reported by two patients (20%) receiving 771 mg/day and seven patients (70%) receiving 1,026 mg/day; followed by nausea, flatulence, asthenia, and headache (each reported in 1 patient [10%] in the 771-mg group) and dizziness (reported in 1 patient [10%] receiving 1,026 mg/day). In the small subgroup (n = 6) who continued taking nelfinavir for longer periods (between 8 and 15 months), virologic responses were sustained in the majority of patients with good tolerability. Nelfinavir is an active HIV-protease inhibitor with favorable pharmacokinetics, good tolerability, and sustained antiviral effects. Results of this early phase I/II dose-ranging study provided data for the safety and antiretroviral activity of nelfinavir and led to the selection of higher doses for phase II/III trials to further optimize virologic and immunologic responses.

Adolescent↗

Low-dose ritonavir moderately enhances nelfinavir exposure.

BACKGROUND: The protease inhibitor ritonavir is increasingly administered at subtherapeutic doses in highly active antiretroviral treatment, to utilize its potential for drug interactions and to enhance the plasma concentrations of other concomitantly prescribed protease inhibitors. The addition of low doses of ritonavir to nelfinavir was investigated to describe the extent of pharmacokinetic interaction. METHODS: In this randomized, open-label, one-sequence crossover study, nelfinavir 1250 mg twice a day was dosed for 17 days, followed by 14 days of nelfinavir 1250 mg twice a day plus low doses of ritonavir of either 100 mg or 200 mg orally. Twenty-four healthy volunteers were evaluated for pharmacokinetics of nelfinavir, its metabolite M8, and ritonavir. Plasma concentrations were measured up to 12 hours after morning and evening dosing, respectively, on days 14 and 31. RESULTS: Ritonavir increased the area under the plasma concentration-time curve (AUC) of nelfinavir by 20% (P =.024) and 39% (P =.001) after morning and evening administration, respectively. The AUC of nelfinavir metabolite M8 was increased by 74% and 86% after morning and evening dosing (P <.001 for both). CONCLUSION: During ritonavir combination therapy a clear although minor drug effect on nelfinavir pharmacokinetics was demonstrated but no dose effect was shown.

Adult↗

Pharmacokinetics and pharmacodynamics of nelfinavir administered twice or thrice daily to human immunodeficiency virus type 1-infected children.

We studied the pharmacokinetics and pharmacodynamics of nelfinavir administered 2 or 3 times per day to human immunodeficiency virus type 1 (HIV-1)-infected children receiving highly active antiretroviral therapy containing nelfinavir. The geometric mean trough concentrations of nelfinavir for the thrice- and twice-daily regimens were 1.55 mg/L and 1.11 mg/L, respectively (P=not significant). Nelfinavir concentrations did not correlate with total daily dose, dose per kilogram of weight, age, weight, previous protease inhibitor (PI) experience, or CD4(+) cell percentage. In the 25 PI-naive children, the virus load reductions at 24 weeks of treatment with the twice- and thrice-daily regimens were comparable. A significantly higher percentage of children in the twice-daily group had a trough concentration of nelfinavir of less than the inhibitory concentration of 95% (P=.042). The decrease in the virus load at 24 weeks of treatment was not correlated with the trough concentration of nelfinavir. The variability of trough concentrations was extremely high, particularly among recipients of the twice-daily regimen, resulting in a higher number of patients with subinhibitory concentrations of nelfinavir in this group.

Antiretroviral Therapy, Highly Active↗

Combination nucleoside analog reverse transcriptase inhibitor(s) plus nevirapine, nelfinavir, or ritonavir in stable antiretroviral therapy-experienced HIV-infected children: week 24 results of a randomized controlled trial--PACTG 377. Pediatric AIDS Clinical Trials Group 377 Study Team.

One hundred eighty-one antiretroviral-experienced, protease inhibitor-naive, clinically stable HIV-infected children between 4 months and 17 years of age were randomly assigned to receive one of four combination regimens to evaluate the change in plasma HIV RNA, safety, and tolerance when changing antiretroviral therapy to a protease inhibitor-containing combination regimen. All four regimens contained stavudine; in addition children received nevirapine plus ritonavir, lamivudine plus nelfinavir, nevirapine plus nelfinavir, or lamivudine plus nevirapine plus nelfinavir. Twelve additional children chose to receive stavudine plus lamivudine plus nelfinavir, with nelfinavir given bid, rather than tid as for the main regimens. Overall, 51% (89/176; 95% CI 43-58%) of the children on the randomized portion of the study had an HIV RNA response (< or =400 copies/ml) on at least two of the three HIV RNA determinations taken at Weeks 8, 12, and 16. At Week 24 the proportion of children with an HIV RNA response still on initial therapy was 47% (83/176; 95% CI 40-55%) and ranged from 41 to 61% for the four randomized treatment arms. Rash was frequently seen (27%) on the treatment arms containing nevirapine. At Week 24 64% (7/11, 95% CI 31-89%) of the children on the bid nelfinavir combination regimen were still on initial therapy with an HIV RNA response as compared with 46% (23/50; 95% CI 32-61%) on the corresponding tid nelfinavir combination regimen. A change in antiretroviral therapy to a protease inhibitor-containing regimen was associated with a virological response rate of approximately 50% for this patient population.

Anti-HIV Agents↗

Long-term efficacy and safety of atazanavir with stavudine and lamivudine in patients previously treated with nelfinavir or atazanavir.

The purpose of the study was to determine long-term efficacy, safety, and tolerability of atazanavir plus stavudine/lamivudine in 346 HIV-infected patients previously treated with atazanavir or nelfinavir. BMS AI424-044 is an ongoing, multicenter, international, open-label, rollover/switch study initiated in June 2001. Patients completing >or=48 weeks in trial BMS AI424-008 with a plasma HIV RNA viral load <10,000 copies/mL were eligible to continue on atazanavir (400 or 600 mg) or to switch from nelfinavir to atazanavir (400 mg) once daily. Antiviral efficacy, change in CD4 cell counts, and effect on lipid parameters were measured. After 24 weeks of atazanavir use in BMS AI424-044, 83%, 85%, and 87% of the atazanavir 400-mg, atazanavir 600-mg, and nelfinavir-to-atazanavir-switched patients, respectively, had HIV RNA levels <400 copies/mL compared with 76%, 76%, and 63%, respectively, at week 48 of BMS AI424-008. Atazanavir-treated patients showed minimal changes in lipid levels compared with baseline. Patients switched from nelfinavir to atazanavir showed significant mean percent decreases in total cholesterol (-16%), fasting low-density lipoprotein cholesterol (-21%), and fasting triglycerides (-28%) (P<0.0001) by week 12 of atazanavir treatment. No new safety issues were identified, and the overall incidence of treatment-emergent adverse events during BMS AI424-044 was comparable across treatment groups. Atazanavir was safe, tolerable, and effective during extended use and in patients switched from nelfinavir. Extended atazanavir use resulted in continued viral suppression and lipid changes that were not clinically relevant. In virologically suppressed nelfinavir-treated patients switched to atazanavir, virologic improvement continued, whereas nelfinavir-induced lipid elevations were reversed within 12 weeks, approaching pretreatment values.

Adult↗

The effect of ravuconazole on the pharmacokinetics of nelfinavir in healthy male volunteers.

An open-label, nonrandomized study was conducted to assess the effect of ravuconazole on the pharmacokinetics of concomitantly administered nelfinavir. Healthy volunteers received 750 mg nelfinavir on day 1, 750 mg nelfinavir and 400 mg ravuconazole on day 2, 400 mg ravuconazole on days 3 to 28, and 750 mg nelfinavir and 400 mg ravuconazole on day 29. The geometric means of C(max) and area under the curve of nelfinavir coadministered with ravuconazole were 30.7% and 31.9% higher on day 2 and 7.9% and 16.2% lower on day 29, respectively, compared to the corresponding values on day 1. These findings are consistent with the potential for ravuconazole to both inhibit and induce CYP3A isozymes. The alterations in the systemic exposure to nelfinavir were within the range defined by the 90% confidence interval. The study data indicate that coadministration of ravuconazole did not result in a clinically significant change in the plasma levels of nelfinavir.

Adolescent↗

Different kinetics of immunologic recovery using nelfinavir or lopinavir/ritonavir-based regimens in children with perinatal HIV-1 infection.

The choice to include the optimal protease inhibitor (PI) in highly active antiretroviral therapy (HAART) regimens in children with perinatal HIV-1 infection is still under debate. Virologic and immunologic outcomes of three different regimens in an observational paediatric cohort were compared. Data from 12 saquinavir-, 18 nelfinavir-, and 10 lopinavir/ritonavir-treated children were analyzed after 4 and 24 weeks of therapy. Immunologic and virologic outcomes were compared using multivariate analysis adjusting the results for age, baseline CD4+ T-lymphocyte count and baseline viral load. Saquinavir-treated children displayed significant reduction in viral load at week 24 (but not at week 4) and no increase in CD4+ T-lymphocyte count, indicating a poor advantage in using this drug. Lopinavir/ritonavir-treated children presented lower viral loads than nelfinavir-treated children at week 4 (P=0.020) and week 24 (P<0.0001). Virologic failure occurred in 6/18 (33.3%) nelfinavir-treated children but in no child receiving lopinavir/ritonavir (P=0.013). An undetectable viral load was achieved in 9/10 (90.0%) lopinavir/ritonavir- vs. 3/18 (16.6%) nelfinavir-treated children (P<0.0001). No significant difference in CD4+ T-lymphocyte count was observed between lopinavir/ritonavir- and nelfinavir-treated children at weeks 4 and 24. However, a different kinetic of the immunologic recovery was observed. Lopinavir/ritonavir-treated children displayed higher CD4+ T-lymphocyte counts than saquinavir-treated children since the first month of therapy (week 4: P=0.042; week 24: P= 0.029) while nelfinavir-treated children took 24 weeks to reach such an outcome (P=0.034). Since lopinavir/ritonavir-based regimen controls viral replication more efficiently and restores CD4+ T-lymphocyte count more quickly than saquinavir- or nelfinavir-based HAART, it may be considered when a salvage therapy or a rapid increase in CD4+ T-lymphocytes is necessary.

Anti-HIV Agents↗

Long-term response in patients receiving HAART including nelfinavir: experience from two Italian centers.

Many studies have demonstrated that the long-term, virological, immunological and clinical effectiveness of highly active antiretroviral therapy (HAART) is mainly related to durable suppression of viral replication. Among the specific antiretroviral agents available today, nelfinavir has been widely used in the last 3 years. This open label, non comparative, retrospective study on 307 patients living with HIV aimed to evaluate the effectiveness of an antiretroviral (ART) regimen including nelfinavir as first-line HAART in terms of rate and durability of viro-immunological response. Most patients, 258/307 (84%), were pre-treated whereas only 49/307 (16%) were treatment naive. The median baseline CD4 cell count was 223 cells/mm3 for naive patients and 317 cells/mm3 for experienced patients whereas median HIV RNA values were 2,500 and 82,000 copies/ml for experienced and naive patients respectively. Median times spent on nelfinavir were 839 and 897 days for experienced and naive patients respectively, with 171/258 pre-treated patients (66%) remaining on nelfinavir-based therapy up to 24 months. Overall, the mean CD4 increase was 196 cells/mm3 with a relevant increment of 165 in experienced patients and 367 cells/mm3 in naive patients (p<0.01). The mean viral load variation in naive patients was -2.22 log10 and in experienced patients -0.53 log10 (p<0.01). In conclusion, nelfinavir, as part of HAART, demonstrated long-term benefit (almost two-thirds of patients stayed on nelfinavir up to 24 months). The response rate in patients naive to antiretroviral therapy was better than for experienced patients. Although there were some differences related to the baseline CD4 level, the overall response rate was good, supporting the role of nelfinavir in HAART.

Adolescent↗

Immunotoxicity evaluation of nelfinavir in rats.

The objective of these investigations was to determine whether exposure to the HIV-1 protease inhibitor nelfinavir compromises immune function in Sprague Dawley rats. Animals (20/sex per group) were exposed orally for 1 or 6 months to nelfinavir at doses of 0 (1% carboxymethylcellulose vehicle), 100, 300 or 1000 mg/kg per day. Animals were observed daily for morbidity/mortality and for clinical signs of toxicity. Body weights were recorded weekly (weeks 1-14) and then monthly thereafter and at study termination. At termination (1 month or 6 months; 10/sex per group), serum was collected and retained for toxicokinetic analysis. The spleen, thymus and liver were removed from each animal and weighed; thymuses and liver were discarded after weighing. Spleens were prepared and immunophenotyping, natural killer (NK) cell activity, and proliferative responses to mitogenic stimuli (e.g., concanavalin A, Salmonella typhimurium) were evaluated. There were no treatment-related effects on immune cell populations (absolute or percent values) or in proliferative responses. At the 1-month interval, a decrease in NK cell activity (0.45-fold control) was noted in male rats at 100 and 1000 mg/kg per day but not at the middle dose of 300 mg/kg per day. Female rats at 1 month were noted for an increase in NK cell activity (1.4-fold control) at 100 mg/kg per day, but there was no difference in the NK response between vehicle-treated animals and those exposed to higher doses of nelfinavir. No effects on NK activity were noted in female animals after 6 months of nelfinavir treatment. Assay difficulties prevented evaluation of male rats at the 6-month interval. Taken together, the absence of a dose-response effect for NK activity in male rats treated for 1 month, the lack of suppressive effects in females treated for either 1 or 6 months, and the unchanged splenic NK cell numbers in nelfinavir-treated animals at both 1 and 6 months suggest that the decreased NK activity noted in male rats at 1 month is not biologically relevant. It was therefore concluded that, under the experimental conditions used, oral treatment with nelfinavir for 1 or 6 months at doses up to 1000 mg/ kg per day is not immunosuppressive in rats. C8hr values following nelfinavir treatment at 1000 mg/kg per day for 6 months were between 1- and 2.7-fold the reported Cmax values in humans.

Administration, Oral↗

Drug resistance mutations in HIV-1-infected subjects during protease inhibitor-containing highly active antiretroviral therapy with nelfinavir or indinavir.

OBJECTIVES: The aim of this retrospective study was to evaluate treatment outcome and characterize the pattern of genotype mutations in subjects with treatment failure on highly active antiretroviral therapy (HAART) containing nelfinavir or indinavir. STUDY DESIGN AND METHODS: The database of the Swiss HIV Cohort Study was screened for all subjects naive to protease inhibitor (PI) treatment who started HAART with nelfinavir or indinavir, responded initially (HIV-RNA <400 copies/ml) and received >24 weeks of treatment. Responders with subsequent treatment failure (HIV-RNA >1000 copies/ml, bordered by HIV-RNA >400 copies/ml) were selected for genotypic analysis. RESULTS: Initial treatment response, maintenance of response and subsequent virological failure were observed at a comparable frequency in 1143 nelfinavir and 1555 indinavir subjects. Of the treatment-naive patients, 13% who took nelfinavir and 16% who took indinavir had HIV-RNA >1000 copies/ml at least once. These values increased to 24 and 27%, respectively, for reverse transcriptase inhibitor-experienced subjects. Genotypic analysis in a subset of subjects with virological failure identified 30N as the only primary mutation in the nelfinavir subjects (8 out of 21, 38%) whereas isolated or combined 82A/T and 461/L mutations were detected in the indinavir subjects (9 out of 20, 45%). CONCLUSIONS: In this population of previously PI-naive subjects, the rate of virological failure and the frequency of resistance mutations at the time of virological failure were comparable in subjects receiving nelfinavir- or indinavir-containing HAART. In nelfinavir subjects, 30N was the only primary mutation whereas isolated or combined 82A/T and 461/L mutations were detected in indinavir subjects.

Acquired Immunodeficiency Syndrome↗

Nelfinavir-induced insulin resistance is associated with impaired plasma membrane recruitment of the PI 3-kinase effectors Akt/PKB and PKC-zeta.

AIMS/HYPOTHESIS: Chronic exposure of 3T3-L1 adipocytes to the HIV protease inhibitor nelfinavir induces insulin resistance, recapitulating key metabolic alterations of adipose tissue in the lipodystrophy syndrome induced by these agents. Our goal was to identify the defect in the insulin signal transduction cascade leading to nelfinavir-induced insulin resistance. METHODS: Fully differentiated 3T3-L1 adipocytes were exposed to 30 micro mol/l nelfinavir for 18 h, after which the amount, the phosphorylation and the localisation of key proteins in the insulin signalling cascade were evaluated. RESULTS: Insulin-induced interaction of phosphatidylinositol 3'-kinase (PI 3-kinase) with IRS proteins was normal in cells treated with nelfinavir, as was IRS-1-associated PI 3-kinase activity. Yet insulin-induced phosphorylation of Akt/protein kinase B (PKB), p70S6 kinase and extracellular signal-regulated kinase 1/2 was significantly impaired. This could not be attributed to increased protein phosphatase 2A activity or to increased expression of phosphoinositide phosphatases (SHIP2 or PTEN). However, insulin failed to induce translocation of the PI 3-kinase effectors Akt/PKB and protein kinase C-zeta (PKC-zeta) to plasma membrane fractions of nelfinavir-treated adipocytes. CONCLUSIONS/INTERPRETATION: We therefore conclude that nelfinavir induces a defect in the insulin signalling cascade downstream of the activation of PI 3-kinase. This defect manifests itself by impaired insulin-mediated recruitment of Akt/PKB and PKC-zeta to the plasma membrane.

3-Phosphoinositide-Dependent Protein Kinases↗

HIV protease inhibitor nelfinavir inhibits replication of SARS-associated coronavirus.

A novel coronavirus has been identified as an etiological agent of severe acute respiratory syndrome (SARS). To rapidly identify anti-SARS drugs available for clinical use, we screened a set of compounds that included antiviral drugs already in wide use. Here we report that the HIV-1 protease inhibitor, nelfinavir, strongly inhibited replication of the SARS coronavirus (SARS-CoV). Nelfinavir inhibited the cytopathic effect induced by SARS-CoV infection. Expression of viral antigens was much lower in infected cells treated with nelfinavir than in untreated infected cells. Quantitative RT-PCR analysis showed that nelfinavir could decrease the production of virions from Vero cells. Experiments with various timings of drug addition revealed that nelfinavir exerted its effect not at the entry step, but at the post-entry step of SARS-CoV infection. Our results suggest that nelfinavir should be examined clinically for the treatment of SARS and has potential as a good lead compound for designing anti-SARS drugs.

Animals↗