Comparison of Pharmacokinetic Profiles of Zolpidem Buffered Sublingual Tablet and Zolpidem Oral Immediate-Release Tablet: Results from a Single-Center, Single-Dose, Randomized, Open-Label Crossover Study in Healthy Adults

Dietary Influence on Drug Efficacy: A Comprehensive Review of Ketogenic Diet-Pharmacotherapy Interactions

It is widely acknowledged that the ketogenic diet (KD) has positive physiological effects as well as therapeutic benefits, particularly in the treatment of chronic diseases. Maintaining nutritional ketosis is of utmost importance in the KD, as it provides numerous health advantages such as an enhanced lipid profile, heightened insulin sensitivity, decreased blood glucose levels, and the modulation of diverse neurotransmitters. Nevertheless, the integration of the KD with pharmacotherapeutic regimens necessitates careful consideration. Due to changes in their absorption, distribution, metabolism, or elimination, the KD can impact the pharmacokinetics of various medications, including anti-diabetic, anti-epileptic, and cardiovascular drugs. Furthermore, the KD, which is characterised by the intake of meals rich in fats, has the potential to impact the pharmacokinetics of specific medications with high lipophilicity, hence enhancing their absorption and bioavailability. However, the pharmacodynamic aspects of the KD, in conjunction with various pharmaceutical interventions, can provide either advantageous or detrimental synergistic outcomes. Therefore, it is important to consider the pharmacokinetic and pharmacodynamic interactions that may arise between the KD and various drugs. This assessment is essential not only for ensuring patients' compliance with treatment but also for optimising the overall therapeutic outcome, particularly by mitigating adverse reactions. This highlights the significance and necessity of tailoring pharmacological and dietetic therapies in order to enhance the effectiveness and safety of this comprehensive approach to managing chronic diseases.

Making a 'sex-difference fact': Ambien dosing at the interface of policy, regulation, women's health, and biology

The U.S. Food and Drug Administration's (FDA) 2013 decision to lower recommended Ambien dosing for women has been widely cited as a hallmark example of the importance of sex differences in biomedicine. Using regulatory documents, scientific publications, and media coverage, this article analyzes the making of this highly influential and mobile 'sex-difference fact'. As we show, the FDA's decision was a contingent outcome of the drug approval process. Attending to how a contested sex-difference fact came to anchor elite women's health advocacy, this article excavates the role of regulatory processes, advocacy groups, and the media in producing perceptions of scientific agreement while foreclosing ongoing debate, ultimately enabling the stabilization of a binary, biological sex-difference fact and the distancing of this fact from its conditions of construction.

Effect of CYP3A4 metabolism on sex differences in the pharmacokinetics and pharmacodynamics of zolpidem

To investigate pharmacokinetic and pharmacodynamic differences of zolpidem between males and females and their causes, including CYP3A4 activity. A single oral dose of zolpidem (10 mg) was administered to 15 male and 15 female healthy subjects. Blood samples were collected up to 12 h post-dose to determine plasma zolpidem concentrations. Pharmacokinetic parameters were obtained using non-compartmental analysis. Digit symbol substitution test, choice reaction time, and visual analog scale of sleepiness were used to evaluate pharmacodynamics. We measured CYP3A4 activity using 4β-hydroxycholesterol, an endogenous metabolite. Mean maximum plasma concentration and area under the plasma concentration–time curve were higher for females than for males (9.9% and 32.5%, respectively); other pharmacokinetic parameters showed no significant differences. Pharmacodynamic scores for females showed delayed recovery compared with that for males. CYP3A4 activity was higher in females than in males (p = 0.030). There was no serious adverse event, and adverse event incidence was not different between the sexes. Zolpidem exposure was about 30% higher in females than in males. Delayed pharmacodynamic score recovery in females could be related to higher zolpidem concentrations. Although apparent clearance was lower in females, systemic clearance might not be the cause of the different exposures to zolpidem.

An explorative approach to understanding individual differences in driving performance and neurocognition in long-term benzodiazepine users

OBJECTIVE

Previous research reported cognitive and psychomotor impairments in long-term users of benzodiazepine receptor agonists (BZRAs). This article explores the role of acute intoxication and clinical complaints.

METHODS

Neurocognitive and on-road driving performance of 19 long-term (≥6 months) regular (≥twice weekly) BZRA users with estimated plasma concentrations, based on self-reported use, exceeding the therapeutic threshold (C_BZRA +), and 31 long-term regular BZRA users below (C_BZRA -), was compared to that of 76 controls.

RESULTS

BZRA users performed worse on tasks of response speed, processing speed, and sustained attention. Age, but not C_BZRA or self-reported clinical complaints, was a significant covariate. Road-tracking performance was explained by C_BZRA only. The C_BZRA  + group exhibited increased mean standard deviation of lateral position comparable to that at blood-alcohol concentrations of 0.5 g/L.

CONCLUSIONS

Functional impairments in long-term BZRA users are not attributable to self-reported clinical complaints or estimated BZRA concentrations, except for road-tracking, which was impaired in CBZRA + users. Limitations to address are the lack of assessment of objective clinical complaints, acute task related stress, and actual BZRA plasma concentrations. In conclusion, the results confirm previous findings that demonstrate inferior performance across several psychomotor and neurocognitive domains in long-term BZRA users.

Evaluation of Physiologically Based Pharmacokinetic Models to Predict the Absorption of BCS Class I Drugs in Different Pediatric Age Groups

Age-related changes in many parameters affecting drug absorption remain poorly characterized. The objective of this study was to apply physiologically based pharmacokinetic (PBPK) models in pediatric patients to investigate the absorption and pharmacokinetics of 4 drugs belonging to the Biopharmaceutics Classification System (BCS) class I administered as oral liquid formulations. Pediatric PBPK models built with PK-Sim/MoBi were used to predict the pharmacokinetics of acetaminophen, emtricitabine, theophylline, and zolpidem in different pediatric populations. The model performance for predicting drug absorption and pharmacokinetics was assessed by comparing the predicted absorption profile with the deconvoluted dose fraction absorbed over time and predicted with observed plasma concentration-time profiles. Sensitivity analyses were performed to analyze the effects of changes in relevant input parameters on the model output. Overall, most pharmacokinetic parameters were predicted within a 2-fold error range. The absorption profiles were generally reasonably predicted, but relatively large differences were observed for acetaminophen. Sensitivity analyses showed that the predicted absorption profile was most sensitive to changes in the gastric emptying time (GET) and the specific intestinal permeability. The drug's solubility played only a minor role. These findings confirm that gastric emptying time, more than intestinal permeability or solubility, is a key factor affecting BCS class I drug absorption in children. As gastric emptying time is prolonged in the fed state, a better understanding of the interplay between food intake and gastric emptying time in children is needed, especially in the very young in whom the (semi)fed condition is the prevailing prandial state, and hence prolonged gastric emptying time seems more plausible than the fasting state.

The promises and pitfalls of sex difference research

Funding agencies in North America and Europe are recognizing the importance of the integration of sex differences into basic and clinical research. Although these mandates are in place to improve our knowledge of health for both men and women, there have been a number of implementation issues that require vigilance on the part of funders and the research community. Here we discuss issues on simple inclusion of both sexes in studies to specialisation of sex differences with attention paid to statistics and the need for sex-specific treatments. We suggest differing mandates need to be considered regarding simple integration versus the need for studies in the specialisation of sex differences and/or the need for research that recognises the importance of male-specific or female-specific factors that influence subsequent health such as menstruation, menopause or pregnancy.

Sublingual and oral zolpidem for insomnia disorder: a 3-month randomized trial

Objective:

To evaluate the safety and efficacy of a 5 mg sublingual dose of zolpidem, compared to a 10 mg oral dose, at bedtime and “as needed” following middle-of-the-night awakenings.

Methods:

Participants were randomized into an oral group (oral zolpidem 10 mg and sublingual placebo at bedtime and “as-needed”) and a sublingual group (oral placebo and sublingual zolpidem 5 mg at bedtime and “as-needed”). Participants underwent medical evaluation, polysomnography, the psychomotor vigilance test, and completed questionnaires.

Results:

Of 85 patients, 67 met the criteria for insomnia (48±10 years; 79% women) and were randomized. Of these, 46 completed 92±5 days of treatment. Mild-to-moderate adverse events were reported by 25% of the participants, including headache, sleepiness, and dizziness. Both treatments decreased middle-of-the-night awakenings by an average of -3.1±2.3 days/week and increased total sleep time by 1.5 hours. Changes in sleep quality and insomnia severity scores were also favorable and comparable between groups: variation depended on continuation of treatment. Regarding PSG findings, sleep latency decreased more in the sublingual group than the oral group (-14±42 vs. 10±29 min; p = 0.03). The psychomotor vigilance test showed minor residual effects 30 minutes after awakening, which reversed after 2 hours.

Conclusions:

The safety and efficacy of both zolpidem formulations are comparable. The sublingual 5 mg dose induced sleep more rapidly.

Clinical trial registration:

NCT01896336

In-vitro–in-silico investigation of the negative food effect of zolpidem when administered as immediate-release tablets

Objectives

The main objective of the present work was to combine in-vitro and in-silico tools to better understand the in-vivo behavior of the immediate release (IR) formulation of zolpidem in the fasted and fed states.

Methods

The dissolution of zolpidem was evaluated using biorelevant media simulating the gastric and intestinal environment in the fasted and fed states. Additionally, the influence of high viscosity and high fat content on the release of zolpidem under fed state conditions was investigated. The in-vitro results were combined with a physiologically based pharmacokinetic (PBPK) model constructed with Simcyp® to simulate the zolpidem pharmacokinetic profile in both prandial states.

Key findings

In vitro biorelevant dissolution experiments representing the fasted and fed states, combinedwith PBPKmodelling, were able to simulate the plasma profiles from the clinical food effect studies well. Experiments reflecting the pH and fat content of themeal led to a good prediction of the zolpidem plasma profile in the fed state, whereas increasing the viscosity of the gastricmedia led to an under-prediction.

Conclusions

This work demonstrates that the combination of biorelevant dissolution testing and PBPK modelling is very useful for understanding the in-vivo behavior of zolpidem in the fasted and fed states. This approach could be implemented in the development of other drugs exhibiting negative food effects, saving resources and bringing new drug products to the market faster.

Zolpidem and Gender: Are Women Really At Risk?

BACKGROUND

In 2013 the Food and Drug Administration (FDA) claimed the existence of new data showing women to be at risk for excessive daytime sedation and impaired driving proficiency following bedtime doses of zolpidem. The putative explanation was the reduced metabolic clearance of zolpidem and higher morning blood concentrations in women compared to men. The FDA acted to reduce the recommended dosage for women down to 50% of the dose for men. No other regulatory agency worldwide has taken similar action.

METHODS

Gender effects on zolpidem pharmacokinetics, pharmacodynamics, adverse effects, clinical efficacy, and driving performance were evaluated through a further analysis of data from a previous study, together with a literature review.

RESULTS

Women had on average 35% lower apparent clearance of zolpidem than men (236 vs 364 mL/min, P < 0.001). This difference was not explained by body weight. In some laboratory studies, women had greater functional impairment than men taking the same dose, but in all studies active drug was not distinguishable from placebo at 8 hours after oral dosage. On-the-road driving studies likewise showed no evidence of driving impairment in men or women at 8 hours after 10 mg of oral immediate-release zolpidem. No clinical trial demonstrated a gender-related difference in clinical efficacy or adverse reactions, and there was no evidence of a particular risk to women.

CONCLUSIONS

Dosage reduction in women is not supported by available scientific evidence, and may in fact lead to underdosing and the consequent hazard of inadequately treated insomnia.

Sleep Pharmacogenetics: The Promise of Precision Medicine

Pharmacogenetics is the branch of personalized medicine concerned with the variability in drug response occurring because of heredity. Advances in genetics research, and decreasing costs of gene sequencing, are promoting tremendous growth in pharmacogenetics in all areas of medicine, including sleep medicine. This article reviews the body of research indicating that there are genetic variations that affect the therapeutic actions and adverse effects of agents used for the treatment of sleep disorders to show the potential of pharmacogenetics to improve the clinical practice of sleep medicine.

Exploration of sexual dimorphism and inter-individual variability in multivariate parameter spaces for a pharmacokinetic compartment model

Pharmacokinetic models are particularly useful to study the underlying and complex physiological mechanisms contributing to clinical differences across patient subgroups or special populations. Unfortunately, the inherent variability of biological systems and knowledge gaps in physiological data limit confidence in model predictions for special populations. Sourcing data to reflect the desired physiologies can be resource intensive, particularly for a larger model. Thus, a critical step in model development for special populations involves an in-depth analysis of model inputs, which can be guided by Monte Carlo simulations. Such an approach enables the generation of parameter values by stochastic sampling that are subsequently restricted to the combinations that describe biologically plausible or target model output. Our approach utilized a published pharmacokinetic compartmental model to demonstrate how sampling in conjunction with global sensitivity analysis can be used to explore sexual dimorphism and inter-individual variability in multivariate parameter spaces for differentiation of model input and behavior across phenotypes. Despite limiting the model output to relatively narrow ranges, male and female phenotypes were associated with wide variability in both individual parameter values and combinations of parameters. Through an integrated approach using a support vector machine, principal component analysis and global sensitivity analysis, our approach revealed that specific combinations of parameters gave rise to a certain phenotype, while individual parameters influenced the shape of plasma concentration profile. Augmenting analysis of the model input with global sensitivity analysis enabled an understanding of both sexual dimorphism and inter-individual variability in pharmacokinetics. While the current study revealed how model input could be separated by sex for a simple compartment model, the approach could be extended to other patient factors, such as age or disease, and to a more complex physiologically-based model that describes absorption, distribution, metabolism, and elimination with more detail.

Zolpidem's use for insomnia

Zolpidem is a short-acting non-benzodiazepine hypnotic drug that belongs to the imidazopyridine class. In addition to immediate-release (IR) and extended-release (ER) formulations, the new delivery forms including two sublingual tablets [standard dose (SD) and low dose (LD)], and an oral spray form have been recently developed which bypass the gastrointestinal tract. So far, Zolpidem has been studied in several clinical populations: cases poor sleepers, transient insomnia, elderly and non-elderly patients with chronic primary insomnia, and in comorbid insomnia. Peak plasma concentration (Tmax) of zolpidem-IR occurs in 45 to 60min, with the terminal elimination half-life (t½) equating to 2.4h. The extended-release formulation results in a higher concentration over a period of more than 6h. Peak plasma concentration is somewhat shorter for the sublingual forms and the oral spray, while their t½ is comparable to that of zolpidem-IR. Zolpidem-IR reduces sleep latency (SL) at recommended doses of 5mg and 10mg in elderly and non-elderly patients, respectively. Zolpidem-ER at doses of 6.25mg and 12.5mg, improves sleep maintenance in elderly and non-elderly patients, respectively, 4h after its administration. Sublingual zolpidem-LD (5mg) and zolpidem oral spray are indicated for middle-of-the-night (MOTN) wakefulness and difficulty returning to sleep, while sublingual zolpidem-SD (10mg) is marketed for difficulty falling asleep. With their array of therapeutic uses and their popularity among physicians and patients; this review describes the clinical pharmacology, indications and uses, identifying withdrawal symptoms, abuse and dependence potentials, and adverse drug reactions are discussed.

Safety analysis of zolpidem in elderly subjects 80 years of age or older: adverse event monitoring in Japanese subjects

OBJECTIVES

Prescriptions of non-benzodiazepine sedative hypnotics, e.g. zolpidem, for insomnia in elderly subjects 80 years of age or older have markedly increased in the USA. However, a meta-analysis of the risks and benefits of hypnotics in older people reported the benefits associated with hypnotics use are outweighed by the risks. This study aimed to investigate the safety of zolpidem administration in extremely old elderly.

METHODS

The prevalence of adverse reactions to zolpidem was investigated in a subpopulation of participants in the Drug Event Monitoring project of the Japan Pharmaceutical Association. A total of 1011 (316 males and 695 females) zolpidem users, including 261 (25.8%) subjects 80 years of age or older without cognitive or mental complications, were eligible for the analysis.

RESULTS

The elderly and female patients were prescribed significantly lower doses of zolpidem than their counterparts. Adverse symptoms after the last prescription were reported by 60 (5.9%) subjects. The most common symptoms were impaired balance and/or falls (1.8%) and morning drowsiness (1.3%). The multiple logistic regression analyses showed that subjects 80 years of age or older were at lower risk of adverse symptoms (odds ratio 0.39, 95% confidence intervals: 0.17-0.88).

CONCLUSION

Our findings in a real-world clinical setting suggest that low-dose zolpidem can be safely prescribed to subjects 80 years of age or older without cognitive or mental complications.

Pharmacokinetics of a Novel Zolpidem Nasal Spray for Rapid Management of Insomnia: First Trial in Humans

STUDY OBJECTIVES

The present single-dose, parallel-group, randomized, double-blind, placebo-controlled study is to evaluate the pharmacokinetics, tolerability and safety of zolpidem tartrate nasal spray (ZNS) as compared to placebo in healthy subjects.

METHODS

Thirty-six healthy subjects participated in this study, with 19 male and 17 female subjects in 3 cohorts (12 subjects per cohort), who were randomly assigned to receive either an intranasal dose of ZNS 1.75 mg, 3.5 mg, 5.0 mg (n = 10 per dose), or an intranasal placebo (n = 2). Multiple venous blood samples were collected for pharmacokinetic analyses.

RESULTS

Plasma zolpidem concentrations rapidly increased after intranasal ZNS 1.75, 3.5, and 5.0 mg with mean T_max of 0.42, 0.76 and 0.50 h, respectively, followed by rapid decreases at all three doses. C_max, AUC_0-t, and AUC_0-∞ were found to increase in a dose-proportional manner. Female subjects had generally higher AUC_0-t, AUC_0-∞, and lower weight-normalized clearance rate (CL/F) than male subjects. In this study, ZNS was safe and well tolerated over the evaluated dose range. There were no serious adverse events.

CONCLUSIONS

Zolpidem was rapidly absorbed and eliminated after intranasal administration of ZNS. Dose proportionality was found at the doses ranged from 1.75 mg to 5.0 mg. Intranasal exposure of zolpidem was generally higher in female subjects than that in male subjects. It could be concluded that ZNS is safe and well tolerated over the evaluated range of intranasal doses.

Physiologically-based pharmacokinetic models: approaches for enabling personalized medicine

Personalized medicine strives to deliver the 'right drug at the right dose' by considering inter-person variability, one of the causes for therapeutic failure in specialized populations of patients. Physiologically-based pharmacokinetic (PBPK) modeling is a key tool in the advancement of personalized medicine to evaluate complex clinical scenarios, making use of physiological information as well as physicochemical data to simulate various physiological states to predict the distribution of pharmacokinetic responses. The increased dependency on PBPK models to address regulatory questions is aligned with the ability of PBPK models to minimize ethical and technical difficulties associated with pharmacokinetic and toxicology experiments for special patient populations. Subpopulation modeling can be achieved through an iterative and integrative approach using an adopt, adapt, develop, assess, amend, and deliver methodology. PBPK modeling has two valuable applications in personalized medicine: (1) determining the importance of certain subpopulations within a distribution of pharmacokinetic responses for a given drug formulation and (2) establishing the formulation design space needed to attain a targeted drug plasma concentration profile. This review article focuses on model development for physiological differences associated with sex (male vs. female), age (pediatric vs. young adults vs. elderly), disease state (healthy vs. unhealthy), and temporal variation (influence of biological rhythms), connecting them to drug product formulation development within the quality by design framework. Although PBPK modeling has come a long way, there is still a lengthy road before it can be fully accepted by pharmacologists, clinicians, and the broader industry.

Alcohol and Aldehyde Dehydrogenases Contribute to Sex-Related Differences in Clearance of Zolpidem in Rats

OBJECTIVES

The recommended zolpidem starting dose was lowered in females (5 mg vs. 10 mg) since side effects were more frequent and severe than those of males; the mechanism underlying sex differences in pharmacokinetics (PK) is unknown. We hypothesized that such differences were caused by known sex-related variability in alcohol dehydrogenase (ADH) expression.

METHODS

Male, female, and castrated male rats were administered 2.6 mg/kg zolpidem, ± disulfiram (ADH/ALDH pathway inhibitor) to compare PK changes induced by sex and gonadal hormones. PK analyses were conducted in rat plasma and rat brain.

KEY FINDINGS

Sex differences in PK were evident: females had a higher C MAX (112.4 vs. 68.1 ug/L) and AUC (537.8 vs. 231.8 h(∗)ug/L) than uncastrated males. Castration induced an earlier T MAX (0.25 vs. 1 h), greater C MAX (109.1 vs. 68.1 ug/L), and a corresponding AUC increase (339.7 vs. 231.8 h(∗)ug/L). Administration of disulfiram caused more drastic C MAX and T MAX changes in male vs. female rats that mirrored the effects of castration on first-pass metabolism, suggesting that the observed PK differences may be caused by ADH/ALDH expression. Brain concentrations paralleled plasma concentrations.

CONCLUSION

These findings indicate that sex differences in zolpidem PK are influenced by variation in the expression of ADH/ALDH due to gonadal androgens.

Treatment of chronic insomnia disorder in menopause: evaluation of literature

OBJECTIVE

Insomnia both as a symptom and as part of chronic insomnia disorder is quite common in menopause. Comorbid conditions, such as restless legs syndrome and obstructive sleep apnea, occur with high prevalence among perimenopausal women with insomnia. Insomnia in this population group is associated with adverse health outcomes, and there are no clear standards on how to treat it.

METHODS

Based on extensive literature search, 76 articles were identified. Two authors independently graded evidence according to the Oxford Centre for Evidence-Based Medicine Levels of Evidence.

RESULTS

Evaluation and treatment of other comorbid sleep disorders are recommended, as is cognitive-behavioral therapy for insomnia. Hormone therapy, eszopiclone, escitalopram, gabapentin, isoflavones, valerian, exercise, and hypnosis are suggested. Zolpidem, quiteiapine XL, citalopram, mirtazapine followed by long-acting melatonin, ramelteon, Pycnogenol, Phyto-Female Complex, yoga, and massage may be considered. Kampo formulas are not recommended. Acupuncture may not be suggested, and cognitive-behavioral therapy that is not tailored for insomnia probably should not be considered.

CONCLUSIONS

Although a variety of interventions are shown to be helpful in improving sleep in menopause, there is a need for well-designed head-to-head trials with uniform outcome measures.

Zolpidem use and motor vehicle collisions in older drivers

OBJECTIVE

Prescription sleep medication use is most prevalent among women and older adults. Morning drowsiness and impaired coordination are side effects of sleep medications that may affect driving safety. The association between current use of zolpidem-containing medications and motor vehicle collisions (MVCs) was evaluated among drivers of advanced age.

METHODS

Participants were current drivers aged ≥70 years residing in north-central Alabama, spoke English, had a valid driver's license, and had driven within the past three months (n = 2000). Current zolpidem use was determined by pill bottle review. The participant's five-year MVC history was determined from Alabama Department of Public Safety accident reports. The five-year MVC and at-fault MVC rate ratios (RR) were estimated comparing zolpidem users with nonusers in the overall sample and a priori-defined age and sex subgroups.

RESULTS

The unadjusted RR (95% confidence interval [CI]) of MVCs comparing zolpidem users with nonusers was attenuated after adjustment (1.46 [1.02-2.08] and 1.38 [0.97-1.98], respectively). Among women, the unadjusted and adjusted RRs (95% CI) were 1.65 (1.03-2.66) and 1.61 (1.00-2.60), respectively. The unadjusted and adjusted RRs (95% CI) among those aged 80 years or more were 2.24 (1.19-4.57) and 2.35 (1.20-4.61), respectively. There were no statistically significant associations among men or participants less than 80 years old. Similar patterns were present for at-fault MVCs.

CONCLUSION

Current zolpidem users, specifically women and individuals aged 80 years or more, had higher MVC rates than nonusers. Practitioners should consider behavioral treatment before initiating low doses of zolpidem and increasing it as needed to achieve restorative sleep in women and individuals aged 80 years or more to reduce the risk of zolpidem-associated MVCs.

Pediatric Sleep Pharmacology: A Primer

"What will you give my child to help him sleep?" is a common question parents ask and some health care providers abhor hearing. Entire families may suffer when one member does not sleep well. Poor sleep may complicate the management of other comorbid conditions. Health care providers may have received only limited education on sleep disorders and are frequently forced to choose between treatment options that are poorly studied in children. Fortunately, when addressed correctly, many children with chronic sleep disorders may improve their sleep and daytime behavior in a relatively short time. This review provides a framework to help understand the causes of poor sleep in children and the potential pharmacologic options.

Development of a Novel Oral Cavity Compartmental Absorption and Transit Model for Sublingual Administration: Illustration with Zolpidem

Intraoral (IO) delivery is an alternative administration route to deliver a drug substance via the mouth that provides several advantages over conventional oral dosage forms. The purpose of this work was to develop and evaluate a novel, physiologically based oral cavity model for projection and mechanistic analysis of the clinical pharmacokinetics of intraoral formulations. The GastroPlus™ Oral Cavity Compartmental Absorption and Transit (OCCAT™) model was used to simulate the plasma concentration versus time profiles and the fraction and rate of intraoral drug transit/absorption for Intermezzo® sublingual tablets (zolpidem tartrate). The model was evaluated by the goodness-of-fit between simulated and observed concentrations and the deviation of key PK parameters (e.g., C max, T max, and AUC). In addition, a sensitivity analysis was conducted to demonstrate the interplay and impact of key modeling parameters on the fraction absorbed via oral mucosa (F a_IO). The OCCAT™ model captured the observed pharmacokinetics for Intermezzo® sublingual tablets (R (2) > 0.9). The predicted deviations (%) for C max, AUC0-inf, AUC0-20 min, and T max were 5.7, 28.0, 11.8, and 28.6%, respectively, indicating good prediction accuracy. The model also estimated ~18% of total drug was absorbed via the IO route. Furthermore, the sensitivity analysis indicated that the F a_IO was not only associated with drug diffusivity and unbound fraction in epithelium tissue (f ut) but also depended on the physicochemical properties of compounds for IO delivery (e.g., solubility and logD pH = 7.4). The novel physiologically based IO absorption OCCAT™ model showed satisfactory performance and will be helpful to guide development of future intraoral formulations.

Gender differences in pharmacokinetics and pharmacodynamics of zolpidem following sublingual administration

The effect of dose and gender on the pharmacokinetics (PK) and pharmacodynamics (PD) of zolpidem after administration of a buffered zolpidem sublingual tablet (ZST; Intermezzo®, Purdue Pharma L.P., Stamford, CT, USA) was evaluated in healthy non-elderly male and female volunteers. Subjects received a single morning dose of ZST (1.0, 1.75, and 3.5 mg) or placebo in a four-way crossover study. In male and female subjects zolpidem PK were linear, with area under the curve (AUC) proportional to dose, and apparent oral clearance and elimination half-life independent of dose. However, AUC averaged 40% to 50% higher in females than in males receiving the same dose. The gender effect was incompletely explained by body weight. In females, ZST produced PD changes consistent with benzodiazepine agonist effects, particularly at the 3.5-mg dose. For several PD variables, PD effects were significantly related to plasma zolpidem concentrations when data were aggregated across subjects. However, there was variability in response among individuals. In males, PD effects of zolpidem seldom differed from placebo regardless of plasma concentration. The findings confirm that zolpidem clearance is lower in females than in males. PD effects of zolpidem from ZST are greater in female subjects, due to a combination of higher plasma concentrations and greater intrinsic sensitivity.

Influence of food on pharmacokinetics of zolpidem from fast dissolving sublingual zolpidem tartrate tablets

Ingesting food can impact the pharmacokinetics of sedative-hypnotic drugs. A buffered zolpidem sublingual tablet (ZST) recently became available for the treatment of middle-of-the-night awakening. In this randomized, open-label, single-site study, the pharmacokinetic profile of ZST was evaluated when administered while fasting and following a standard high-fat meal (fed state). Healthy adults aged 18-64 years received a single morning dose of 3.5 mg ZST in the fed or fasting state. From 20 min to 3 h post-dose, zolpidem plasma levels were lower in the fed state compared to the fasting state. After 4 h post-dose (corresponding to "morning wake time"), higher zolpidem plasma levels were evident in the fed state. Area under the concentration-time curve (AUC) values for the 0-8 h interval were 160 ng/mL h in the fed state and 203 ng/mL h in the fasting state (P < .001). In the fed versus fasting states, Cmax was 32.0 ng/mL versus 57.3 ng/mL (P < .001), respectively, and Tmax was 3.0 h versus 0.92 h (P < .001), respectively. Together these data suggest that administration of ZST in the fed state is not optimal for maximizing the likelihood of therapeutic benefit and minimizing the probability of residual sedation.