Influence of body weight and UGT2B7 polymorphism on varenicline exposure in a cohort of smokers from the general population.

PURPOSE: The abstinence rate to tobacco after varenicline treatment is moderate and might be partially affected by variability in varenicline concentrations. This study aimed at characterizing the sources of variability in varenicline pharmacokinetics and to relate varenicline exposure to abstinence. METHODS: The population pharmacokinetic analysis (NONMEM®) included 121 varenicline concentrations from 82 individuals and tested the influence of genetic and non-genetic characteristics on apparent clearance (CL/F) and volume of distribution (V/F). Model-based average concentrations over 24 h (Cav) were used to test the impact of varenicline exposure on the input rate (Kin) expressed as a function of the number of cigarettes per day in a turnover model of 373 expired carbon monoxide levels. RESULTS: A one-compartment model with first-order absorption and elimination appropriately described varenicline concentrations. CL/F was 8.5 L/h (coefficient of variation, 26%), V/F was 228 L, and the absorption rate (ka) was fixed to 0.98 h-1. CL/F increased by 46% in 100-kg individuals compared to 60-kg individuals and was found to be 21% higher in UGT2B7 rs7439366 TT individuals. These covariates explained 14% and 9% of the interindividual variability in CL/F, respectively. No influence of varenicline Cav was found on Kin in addition to the number of cigarettes. CONCLUSIONS: Body weight mostly and to a smaller extent genetic polymorphisms of UGT2B7 can influence varenicline exposure. Dose adjustment based on body weight and, if available, on UGT2B7 genotype might be useful to improve clinical efficacy and tolerability of varenicline.

Immediate release tablet formulation of varenicline salicylate and comparative pharmacokinetic study in human volunteers.

PURPOSE: To develop an immediate release-type tablet containing varenicline salicylate (VRC-S), a smoking cessation agent, formulation and stability studies were performed. The in vitro dissolution and in vivo pharmacokinetic (PK) behavior of the tablets were compared with those of the commercial product (Champix) as a reference. MATERIALS AND METHODS: The characteristics of the powder were investigated by particle morphology, size distribution, solubility, hygroscopicity, differential scanning calorimetry, and powder X-ray diffraction. Based on the drug-excipient compatibility test, different VRC-S tablets were prepared with the selected excipients through direct compression or wet granulation method and subjected to a dissolution test. The stability of the most promising VRC-S tablet (F4) was evaluated under accelerated conditions (40°C and 75% relative humidity). Further, the dissolution and human pharmacokinetic profiles of the F4 tablet and Champix were compared. RESULTS: VRC-S showed a positively skewed unimodal size distribution with a specific surface area of 2.02 m2/g, single endothermic peak of 225.2°C in differential scanning calorimetry, crystalline internal structure in powder X-ray diffraction, aqueous solubility of 244.7 mg/mL, and hygroscopicity of 0.256 mg/g. The wet granulation method was preferred for tablet preparation and employed the following excipients: microcrystalline cellulose and anhydrous dibasic calcium phosphate as diluents, croscarmellose sodium as a disintegrant, and colloidal silicon dioxide and magnesium stearate as lubricants. The F4 tablet was stable for 6 months under accelerated conditions. The dissolution of VRC was pH independent, revealing f 2 values of 76.49 and 68.38 at pH 1.2 and pH 6.8, respectively. After the oral administration of F4 tablet and Champix to healthy human volunteers, pharmacokinetic parameters, including time to reach the maximum plasma concentration (Tmax), maximum plasma concentration (Cmax), and area under the curve from 0 to infinity (AUCinf), were compared. The values of 90% CI were 0.972-1.035 for Cmax and 0.982-1.075 for AUCinf, which was indicative of the bioequivalence of both products. CONCLUSION: VRC-S-containing F4 tablet might be a good candidate for smoking cessation treatment.

Effects of varenicline on cognitive performance in heavy drinkers: Dose-response effects and associations with drinking outcomes.

Varenicline reduces drinking in people with alcohol use disorder, but little is known about the mechanisms underlying this effect. Varenicline targets α4ß2 and α7 nicotinic acetylcholine receptors, which are associated with several cognitive functions such as working memory. Varenicline may improve drinking outcomes by enhancing cognitive functioning. The current manuscript reports on cognitive outcomes from a placebo-controlled, double-blind human laboratory experiment examining the effects of varenicline on drinking behavior (Verplaetse et al., 2016a). Participants were 55 adult heavy drinkers who met criteria for an alcohol use disorder. They were randomized to receive varenicline (1 mg/day, 2 mg/day) or placebo. They completed a baseline assessment of cognitive functioning (i.e., digits backward task, continuous performance task) before starting medication. After a medication titration period, they attended a laboratory session (post medication Day 8) where they completed the cognitive assessment battery and an alcohol-primed ad libitum drinking task. Blood was collected to measure plasma varenicline levels. Varenicline produced dose-dependent improvements in working memory. Although there was no significant effect of oral varenicline dose on response time on the continuous performance task, participants with higher levels of plasma varenicline showed greater improvement of reaction time (RT). Among participants receiving 2 mg/day varenicline, larger improvements in working memory were associated less drinking, although mediation analyses did not find a significant indirect effect. These findings suggest that varenicline can improve working memory above baseline levels in heavy drinkers. Varenicline may reduce rates of alcohol use by improving working memory. (PsycINFO Database Record

Effects of varenicline on alcohol self-administration and craving in drinkers with depressive symptoms.

Varenicline (VAR) is approved to aid in smoking cessation and has been shown to be effective for reducing alcohol consumption in heavy drinkers. Little is known, however, about treatment moderators that may influence efficacy. The current study reanalyzed data from a human laboratory study (Verplaetse et al., 2016) to determine whether VAR was more effective at reducing alcohol use among drinkers reporting symptoms of depression. Participants were 60 adults meeting DSM-IV criteria for alcohol use disorders ( n = 60) who were randomly assigned to receive VAR (1 mg/day, 2 mg/day) or placebo. Following 7 days of medication pretreatment, participants attended a laboratory testing session. They provided self-reported ratings of alcohol craving and performed an ad libitum alcohol consumption task after receiving a priming dose of alcohol (target blood alcohol concentration = 0.030 g/dL). Higher blood VAR plasma levels were associated with less alcohol craving and less drinking among participants with more depressive symptoms. Among participants with fewer depressive symptoms, VAR was associated with more drinking during the ad libitum drinking task. These findings show that depression symptoms may be a moderator of VAR efficacy in alcohol users and provides evidence for the role of nAChRs in depression and alcohol use.

The discriminative stimulus effects of i.v. nicotine in rhesus monkeys: Pharmacokinetics and apparent pA2 analysis with dihydro-ß-erythroidine.

Quantitative analysis of antagonism is infrequently used to identify nAChRs mediating behavioral effects. Here, nicotine (0.032 mg/kg i.v.) was established as a discriminative stimulus in rhesus monkeys responding under a fixed ratio 5 schedule; pharmacokinetics and underlying nAChR mechanism(s) were examined. When measured up to 4 h in venous blood, the training dose resulted in the following mean pharmacokinetic parameters: nicotine Cmax = 71.7 ng/ml, t1/2 = 116 min, and clearance = 6.25 ml/min/kg; cotinine Cmax = 191 ng/ml; and 3OH-cotinine Cmax = 63 ng/ml. The ED50 value of nicotine to produce discriminative stimulus effects was 0.013 mg/kg. Epibatidine and varenicline increased drug-lever responding to 97% and 95%, respectively (ED50 values = 0.00015 and 0.031 mg/kg, respectively), whereas cocaine, midazolam, and morphine produced no more than 28% drug-appropriate responding. Mecamylamine and dihydro-ß-erythroidine (DHßE) dose-dependently attenuated the discriminative stimulus effects of the nicotine training dose, whereas methyllycaconitine (MLA) did not. DHßE (0.1 and 0.32) produced rightward shifts of the nicotine and varenicline dose-response functions; Schild plots fitted through individual data resulted in slopes that were not different from unity; the apparent pA2 calculated for DHßE did not significantly differ in the presence of nicotine (6.58) or varenicline (6.45). Compared to human cigarette smoking, nicotine blood levels after 0.032 mg/kg nicotine i.v. took a similar time to reach maximal concentration, levels at Cmax were similar to smoking 2-3 cigarettes, while average nicotine levels were comparable to smoking 5-6 cigarettes. Apparent pA2 analysis with DHßE under these conditions is consistent with nicotine and varenicline acting through the same nAChRs to produce discriminative stimulus effects.