Twenty-four-week efficacy and safety of switching virologically suppressed HIV-1-infected patients from nevirapine immediate release 200 mg twice daily to nevirapine extended release 400 mg once daily (TRANxITION).

OBJECTIVES: Once-daily (qd) antiretroviral therapies improve convenience and adherence. If found to be effective, nevirapine extended release (NVP XR) will confer this benefit. The TRANxITION trial examined the efficacy and safety of switching virologically suppressed patients from NVP immediate release (NVP IR) 200 mg twice daily to NVP XR 400 mg qd. METHODS: An open-label, parallel-group, noninferiority, randomized (2:1 NVP XR:NVP IR) study was performed. Adult HIV-1-infected patients receiving NVP IR plus a fixed-dose nucleoside reverse transcriptase inhibitor (NRTI) combination of lamivudine (3TC)/abacavir (ABC), tenofovir (TDF)/emtricitabine (FTC) or 3TC/zidovudine (ZDV) with undetectable viral load (VL) were enrolled in the study. The primary endpoint was continued virological suppression with VL < 50 HIV-1 RNA copies/mL up to week 24 (calculated using a time to loss of virological response algorithm). Cochran's statistic (background regimen adjusted) was used to test noninferiority. Adverse events (AEs) were recorded. RESULTS: Among 443 randomized patients, continued virological suppression was observed in 93.6% (276 of 295) of NVP XR- and 92.6% (137 of 148) of NVP IR-treated patients, an observed difference of 1% [95% confidence interval (CI) -4.3, 6.0] at 24 weeks of follow-up. Noninferiority (adjusted margin of -10%) of NVP XR to NVP IR was robust and further supported by SNAPSHOT analysis. Division of Acquired Immunodeficiency Syndrome (DAIDS) grade 3 and 4 events were similar for the NVP XR and NVP IR groups (3.7 vs. 4.1%, respectively), although overall AEs were higher in the NVP XR group (75.6 vs. 60.1% for the NVP-IR group). CONCLUSIONS: NVP XR administered once daily resulted in continued virological suppression at week 24 that was noninferior to that provided by NVP IR, with similar rates of moderate and severe AEs. The higher frequency of overall AEs with NVP XR may be a consequence of the open-label design.

Safety, tolerability and pharmacokinetics of BIBN 4096 BS, the first selective small molecule calcitonin gene-related peptide receptor antagonist, following single intravenous administration in healthy volunteers.

BIBN 4096 BS ([R-(R*,S*)]-N-[2-[[5-amino-1-[[4-(4-pyridinyl)-1-piperazinyl]carbonyl]pentyl]amino]-1-[(3,5-dibromo-4-hydroxyphenyl)methyl]-2-oxoethyl]-4-(1,4-dihydro-2-oxo-3(2H)-quinazolinyl)-,1-piperidinecarboxamide) is the first selective, highly potent, small molecule, nonpeptide calcitonin gene-related peptide (CGRP) receptor antagonist, which has been developed for the treatment of acute migraine. The objective of this study was to obtain information on the safety, tolerability and pharmacokinetics of BIBN 4096 BS following single intravenous administration of rising doses (0.1, 0.25, 0.5, 1, 2.5, 5 and 10 mg) in 55 healthy male and female volunteers. The study was of single-centre, double-blind (within dose levels), placebo-controlled, randomized, single rising dose design. Blood pressure, pulse rate, respiratory rate, ECG, laboratory tests and forearm blood flow did not reveal any clinically relevant, drug-induced changes. Sixteen adverse events (AEs) were reported by eight of 41 volunteers after BIBN 4096 BS compared to five AEs reported by four of 14 volunteers after placebo. Approximately two-thirds of all AEs related to active treatment occurred at the highest dose of 10 mg. At this dose level, all AEs were confined to the three BIBN 4096 BS-treated females, and consisted mainly of transient and mild paresthesias. Paresthesias were the single most frequent AE, whereas fatigue was the AE which occurred in the highest number of subjects. Only two AEs were of moderate intensity, all remaining AEs were of mild intensity. No serious AEs were reported. The local tolerability after intravenous administration was good. In summary, intravenously administered BIBN 4096 BS revealed a very favourable safety profile over the dose range tested in both genders. Generally well tolerated at all dose levels, it was of satisfactory tolerability in female subjects at the highest dose of 10 mg. The plasma concentration-time courses of BIBN 4096 BS showed multicompartmental disposition characteristics. Mean maximum concentration (Cmax) values appeared to be dose-proportional. Based on the results from the two high dose levels (5 and 10 mg) with sufficient individual subject data, BIBN 4096 BS exhibited a total plasma clearance (CL) of approximately 12 l/h and an apparent volume of distribution at steady state (Vss) of approximately 20 l, resulting in a terminal half-life (t1/2) of approximately 2.5 h. Inter-individual variability was moderate with a coefficient of variation of approximately 45% based on the area under the plasma concentration-time curve (AUC) values. The mean renal clearance (CLR) was approximately 2 l/h, suggesting that renal excretion plays only a minor role in the elimination of unchanged BIBN 4096 BS.

Pharmacokinetics of nevirapine and lamivudine in patients with HIV-1 infection.

The purpose of this parallel treatment group, double-blind, multicenter study was to characterize the pharmacokinetics of nevirapine and lamivudine when coadministered to patients with the HIV-1 infection. This pharmacokinetic interaction study was nested within a larger Phase III clinical trial conducted to characterize the safety and efficacy of coadministered nevirapine and lamivudine. One hundred HIV-1 infected patients with CD4+ lymphocyte counts < 200 cells/mm3and who were on a background of nucleoside (zidovudine [ZDV], didanosine [ddI], zalcitabine [ddC], stavudine [d4T]) therapy were randomly assigned to be treated with either nucleoside + lamivudine + nevirapine or nucleoside + lamivudine + placebo. Each patient underwent blood sampling at defined times for the purpose of determining the concentration of nevirapine in plasma and lamivudine in serum under steady-state conditions. Each patient was also monitored closely for concomitant administration of other drugs, including ZDV, ddI, ddC, d4T and cotrimoxazole. The pharmacokinetics of nevirapine and lamivudine were characterized using nonlinear mixed-effects modeling. There were no reported serious adverse events during the 40-day pharmacokinetic study. The results of the modeling analysis revealed that nevirapine had no effect on the pharmacokinetics of lamivudine. Estimates of the apparent clearance for nevirapine (CL/F = 3.3 L/hour; 95% confidence interval [CI] 2.9 to 3.7 L/hour) and lamivudine (CL/F 27.6 L/hour; 95% CI 22 to 33.2 L/hour) were consistent with the values reported in earlier trials. However, the results also showed that concomitant administration of lamivudine with cotrimoxazole resulted in a 31% reduction in the apparent clearance of lamivudine, resulting in a 43% increase in the average steady-state lamivudine serum concentrations. These results indicate that chronic concurrent administration of cotrimoxazole with lamivudine may significantly affect the steady-state pharmacokinetics of lamivudine.

Population pharmacokinetic modeling of isoniazid, rifampin, and pyrazinamide.

Isoniazid (INH), rifampin (RIF), and pyrazinamide (PZA) are the most important drugs for the treatment of tuberculosis (TB). The pharmacokinetics of all three drugs in the plasma of 24 healthy males were studied as part of a randomized cross-over phase I study of two dosage forms. Subjects ingested single doses of INH at 250 mg, RIF at 600 mg, and PZA at 1,500 mg. Plasma was collected for 36 h and was assayed by high-performance liquid chromatography. The data were analyzed by noncompartmental, iterative two-stage maximum a posteriori probability Bayesian (IT2B) and nonparametric expectation maximization (NPEM) population modeling methods. Fast and slow acetylators of INH had median peak concentrations in plasma (C[max]) of 2.44 and 3.64 microg/ml, respectively, both of which occurred at 1.0 h postdose (time of maximum concentrations of drugs in plasma [T(max)]), with median elimination half-lives (t1/2) of 1.2 and 3.3 h, respectively (by the NPEM method). RIF produced a median C(max) of 11.80 microg/ml, a T(max) of 1.0 h, and a t1/2 of 3.4 h. PZA produced a median C(max) of 28.80 microg/ml, a T(max) of 1.0 h, and a t1/2 of 10.0 h. The pharmacokinetic behaviors of INH, RIF, and PZA were well described by the three methods used. These models can serve as benchmarks for comparison with models for other populations, such as patients with TB or TB with AIDS.

Pharmacokinetics and clinical effects of oxybutynin in geriatric patients.

The pharmacokinetics and clinical effects of oxybutynin were examined among 21 elderly (mean age 84 years) patients with urge incontinence and detrusor instability or hyperreflexia. The drug did not accumulate to high levels after a week of treatment at dosages of either 2.5 or 5 mg. 3 times per day, and the mean peak level on 5 mg. among the elderly (12.5 ng. per ml.) was not statistically different than the mean peak level reported after the same dosage in young healthy men (8.9 ng. per ml., p equals 0.4). There were no clinically meaningful changes in heart rate, blood pressure or intraocular pressure during the treatment periods. Two-thirds of the patients suffered at least 1 side effect, most commonly dryness of the mouth that was not severe enough to warrant discontinuation of the drug. These data suggest that oxybutynin chloride at dosages of 2.5 to 5 mg. 3 times per day is safe for use in the elderly, even among octogenarians. Statements about its effectiveness and efficacy in the geriatric population must await controlled clinical trials.

Lack of effect of sucralfate on prednisone bioavailability.

The relative bioavailability of single oral doses of prednisone with and without sucralfate administration was determined in 12 healthy male volunteers. Each subject participated in a randomized three-way cross-over study consisting of the following three phases: treatment A, prednisone given alone; treatment B, 2 days pretreatment with sucralfate with a concomitant dose of sucralfate administered with prednisone; and treatment C, 2 days pretreatment with sucralfate with a sucralfate dose administered 2 h after the oral prednisone dose. Plasma prednisolone concentrations (active moiety of prednisone) were determined by a specific and sensitive high-performance liquid chromatographic assay and unbound prednisolone concentrations were determined by equilibrium dialysis. Bioavailability was assessed by comparing the areas under the plasma prednisolone concentration-time curves as well as peak concentrations, time to peak concentration, elimination rate constant, and half-life. No significant differences were noted in any of the treatment phases for any of the parameters except for the time of peak concentration which was slightly delayed from 1.0 +/- 0.6 to 1.7 +/- 0.9 h when sucralfate was concomitantly administered with the prednisone. Thus, the data from this study indicate that sucralfate does not have a clinically significant effect on the bioavailability of orally administered prednisone. The use of these two drugs in combination does not result in an interaction requiring dosage regimen alteration.

Liquid chromatographic determination of propoxyphene and norpropoxyphene in plasma and breast milk.

A sensitive and specific high-performance liquid chromatographic (HPLC) procedure was developed for determination of propoxyphene and norpropoxyphene in plasma and breast milk. The compounds were isolated from the biological specimen by extraction, the organic phase was evaporated to dryness, and the residue was redissolved in mobile phase [acetonitrile: 0.002 M H2SO4 (1:1)]. The resultant solution was then injected into an HPLC system utilizing a C18 reversed-phase analytical column and a variable-wavelength detector set at 205 nm. Under these conditions the method has a sensitivity of 20 ng/mL using 1 mL of plasma or milk. The within-run coefficient of variation for both compounds varied between 6.2 and 8.9% within the concentration range tested. Applicability of the method was demonstrated in a nursing mother who received multiple oral doses of propoxyphene.

Factors affecting the plasma protein binding of verapamil and norverapamil in man.

The in vitro and vivo binding of the antiarrhythmic agent verapamil and its active metabolite norverapamil to human plasma proteins was determined under different conditions at 37 degrees C by equilibrium dialysis. The binding of verapamil was considerable (free fraction of about 0.10) and was independent of plasma concentration over the range of 50 ng/ml to 1500 ng/ml. Norverapamil was also extensively bound to plasma proteins. Verapamil binding was reduced significantly upon plasma dilution and upon addition of three of its major metabolites (norverapamil and metabolites A and B). Therapeutic concentrations of several drugs including disopyramide (12 micrograms/ml), diazepam (2 micrograms/ml), lidocaine (4 micrograms/ml), propranolol (150 ng/ml), and salicylate (250 microgram/ml) also significantly increased the free fraction of verapamil. The results of in vivo protein binding studies using plasma samples collected during a steady-state dosing interval from a patient receiving 80 mg of verapamil orally every 6 hr were similar to those obtained from vitro binding studies.

A simple ultrasound method to characterize in vitro plaque inhibition activity.

A method employing ultrasound vibration for evaluating in vitro plaque derived from Streptococcus mutans was developed. It successfully detected small changes in the cohesive/adhesive characteristics of deposits briefly exposed to several antibacterials and "antiadherents". Increased structural fragility and diminished plaque growth were generally associated with the antibacterials.