Pharmacokinetics of three doses of sublingual testosterone in healthy premenopausal women

The enhancing effects of testosterone in exposure treatment for social anxiety disorder: a randomized proof-of-concept trial

Individuals with a social anxiety disorder (SAD) show hypofunctioning of the hypothalamus-pituitary-gonadal (HPG) axis, which is linked to social fear and avoidance behavior. As testosterone administration has been shown to facilitate social-approach behavior in this population, it may enhance the effectiveness of exposure treatment. In this proof-of-concept study, we performed a randomized clinical assay in which 55 women diagnosed with SAD received two exposure therapy sessions. Session 1 was supplemented with either testosterone (0.50 mg) or placebo. Next, transfer effects of testosterone augmentation on within-session subjective fear responses and SAD symptom severity were assessed during a second, unenhanced exposure session (session 2) and at a 1-month follow-up, respectively. The participants having received testosterone showed a more reactive fear pattern, with higher peaks and steeper reductions in fear levels in session 2. Post-hoc exploration of moderating effects of endogenous testosterone levels, revealed that this pattern was specific for women with high basal testosterone, both in the augmented and in the transfer session. In contrast, the participants with low endogenous testosterone showed reduced peak fear levels throughout session 1, again with transfer to the unenhanced session. Testosterone did not significantly affect self-reported anxiety. The effects of testosterone supplementation on fear levels show transfer to non-enhanced exposure, with effects being modulated by endogenous testosterone. These first preliminary results indicate that testosterone may act on important fear mechanisms during exposure, providing the empirical groundwork for further exploration of multi-session testosterone-enhanced exposure treatment for SAD.

The Effect of Food on the Pharmacokinetics of Buspirone After Single Administration of a Sublingual Testosterone and Oral Buspirone Combination Tablet in Healthy Female Subjects

Introduction

A new combination tablet containing sublingual testosterone and oral buspirone (T+B) was developed to benefit a subgroup of women suffering from female sexual interest/arousal disorder, caused by dysfunctionally overactive sexual inhibition.

Aim

The aim of this study was to compare the effect of food intake on the pharmacokinetics of buspirone, administered as a dual-route, dual-release combination tablet containing 0.5 mg testosterone (T) and 10 mg buspirone (B).

Methods

19 healthy women took T+B under fed and fasted conditions during 2 overnight visits. The blood was sampled over a 24-hour period to determine the pharmacokinetics of buspirone and its active metabolite 1-(2-pyrimidinyl)piperazine (1-PP). Total testosterone levels were also assessed, at 5 time points and for quality control purposes only, as sublingual testosterone uptake is not expected to be influenced by prior food intake.

Main Outcome Measure

PK profiles of buspirone and 1-PP.

Results

For buspirone, the 90% confidence intervals (CIs) of the observed fed/fasted ratios for the plasma area under the curve (AUC)_0-last, AUC_0-inf, and C_max after administration of T+B were not contained within the prespecified bounds of 80% and 125%, except for the lower bound of AUC_0-inf. However, the 90% CIs of the observed fed/fasted ratios for the plasma AUC_0-last, AUC_0-inf, and C_max of 1-PP were contained within the prespecified bounds, with the exception of the upper bound for C_max. The mean AUCs and C_max for 1-PP did not differ between fed and fasted conditions.

Conclusions

Administration of T+B after high-caloric food intake increased the bioavailability of buspirone but did not result in differences in T_max when compared with fasted conditions. Both in fed and fasted conditions, T+B was generally well tolerated and safe. Exposure of 1-PP in fed and fasted conditions was comparable in both conditions. These results demonstrate that T+B can safely and effectively be used in both fed and fasted states.

Gerritsen J, Bloemers J, van Rooij K, et al. The Effect of Food on the Pharmacokinetics of Buspirone After Single Administration of a Sublingual Testosterone and Oral Buspirone Combination Tablet in Healthy Female Subjects. J Sex Med 2020;8:186–194.

The Effect of Food on the Pharmacokinetics of Sildenafil after Single Administration of a Sublingual Testosterone and Oral Sildenafil Combination Tablet in Healthy Female Subjects

INTRODUCTION

Female sexual interest/arousal disorder (FSIAD) affects many women worldwide, but pharmacological treatment options are scarce. A new medicine being developed for FSIAD is an on-demand, dual-route, dual-release drug combination product containing 0.5 mg testosterone (T) and 50 mg sildenafil (S), referred to here as T+S.

AIM

The aim of this study was to compare the effect of a fed and a fasted state on the pharmacokinetics of sildenafil following administration of T+S.

METHODS

Eighteen healthy women were administered T+S under fed and fasted conditions during 2 separate overnight visits in this randomized, open-label, balanced, 2-period, 2-treatment, 2-sequence crossover study.

MAIN OUTCOME MEASURES

The pharmacokinetics of sildenafil and its active metabolite N-desmethyl sildenafil were determined over a 24-hour period. Total testosterone was assessed only at a limited number of time points for quality purposes, as sublingual uptake is not expected to be affected by food intake.

RESULTS

The observed geometric mean ratios (GMRs) and 90% confidence intervals of sildenafil were not all contained within the prespecified bounds (0.80, 1.25). The GMR (90% CI) for plasma AUC_0-last was 1.2753 (0.9706-1.6755); for AUC_0-14h, it was 1.7521 (1.0819-2.8374); and for C_max, it was 1.5591 (0.8634-2.8153). Only lower limits of the CIs fell within the bounds. For N-desmethyl sildenafil, the GMR (90% CI) for AUC_0-last was 0.8437 (0.6738-1.0564); for AUC_0-10h, it was 1.0847 (0.7648-1.5383); and for C_max, it was 1.0083 (0.6638-1.5318). Only the GMRs were contained within bounds. No differences were observed between plasma testosterone C_max and T_max under fed and fasted conditions, which is in line with expectations for a sublingual administration.

CLINICAL IMPLICATIONS

The T+S combination tablet ruptures too late when taken in a fasted state and should therefore not be taken on an empty stomach.

STRENGTHS & LIMITATIONS

This is a well-controlled study that provides important insights into the performance characteristics of the delayed-release coating of the combination tablet. The higher variability of the pharmacokinetic parameters in the fasted state was caused by severely delayed rupture in one-third of the women. A reason for this is proposed but the present data do not explain this phenomenon.

CONCLUSION

The pharmacokinetics of sildenafil from this modified-release tablet are more robust under fed conditions as compared to the artificial fasted condition where no food is consumed 10 hours prior to and 4 hours after dosing. The dosing situation under the tested fasting condition does not represent the expected common use of this product. Patients should, however, be instructed not to take the tablet on an empty stomach. Bloemers J, Gerritsen J, van Rooij K, et al. The Effect of Food on the Pharmacokinetics of Sildenafil After Single Administration of a Sublingual Testosterone and Oral Sildenafil Combination Tablet in Healthy Female Subjects. J Sex Med 2019; 19:1433-1443.

Testosterone reduces functional connectivity during the 'Reading the Mind in the Eyes' Test

Women on average outperform men in cognitive-empathic abilities, such as the capacity to infer motives from the bodily cues of others, which is vital for effective social interaction. The steroid hormone testosterone is thought to play a role in this sexual dimorphism. Strikingly, a previous study shows that a single administration of testosterone in women impairs performance on the 'Reading the Mind in Eyes' Test (RMET), a task in which emotions have to be inferred from the eye-region of a face. This effect was mediated by the 2D:4D ratio, the ratio between the length of the index and ring finger, a proxy for fetal testosterone. Research in typical individuals, in individuals with autism spectrum conditions (ASC), and in individuals with brain lesions has established that performance on the RMET depends on the left inferior frontal gyrus (IFG). Using functional magnetic resonance imaging (fMRI), we found that a single administration of testosterone in 16 young women significantly altered connectivity of the left IFG with the anterior cingulate cortex (ACC) and the supplementary motor area (SMA) during RMET performance, independent of 2D:4D ratio. This IFG-ACC-SMA network underlies the integration and selection of sensory information, and for action preparation during cognitive empathic behavior. Our findings thus reveal a neural mechanism by which testosterone can impair emotion-recognition ability, and may link to the symptomatology of ASC, in which the same neural network is implicated.

Testosterone administration in females modulates moral judgment and patterns of brain activation and functional connectivity

Morality is defined as prescriptive norms regarding how people should treat one another, and includes concepts of fairness, justice, and rights. One recent study with moral dilemmas suggested that testosterone administration increases utilitarian judgments, which depends on second-to-fourth (2D: 4D) digit ratio, as a proxy of prenatal priming. However, the neural mechanism by which acute testosterone modulates moral reasoning remains to be determined. Using a placebo-controlled within-subject design, the current study examined the neuromodulatory effect of testosterone in young females by combining moral dilemmas, 2D: 4D, functional magnetic resonance imaging (fMRI), and subjective ratings of morally laden scenarios. Results showed that testosterone administration elicited more utilitarian responses to evitable dilemmas. The high 2D: 4D group scored more punishments for moral evaluation, whereas the low 2D: 4D group did the opposite. The activity in the amygdala, anterior insular cortex, and dorsolateral prefrontal cortex (dlPFC) was increased when participants evaluated morally unorthodox actions (intentional harm). The activity in the posterior superior temporal sulcus/temporoparietal junction (pSTS/TPJ) to accidental harm was decreased, specific to the high 2D: 4D group. The functional connectivity between the amygdala and dlPFC was reduced. The activity in the pSTS/TPJ to perceived agency predicted utilitarian responses to evitable dilemmas. The findings demonstrate the acute effect of testosterone on neural responses associated with moral judgment, and provide evidence to support that prenatal sex-hormones priming could be important for early neurodevelopment, which plays a crucial role in the neural and behavioral manifestations of testosterone on adult moral reasoning. Hum Brain Mapp 37:3417-3430, 2016. © 2016 Wiley Periodicals, Inc.

Single dose sublingual testosterone and oral sildenafil vs. a dual route/dual release fixed dose combination tablet: a pharmacokinetic comparison

AIM

The aim was to compare the pharmacokinetic profiles of two formulations of a combination drug product containing 0.5 mg testosterone and 50 mg sildenafil for female sexual interest/arousal disorder. The prototype (formulation 1) consists of a testosterone solution for sublingual administration and a sildenafil tablet that is administered 2.5 h later. The dual route/dual release fixed dose combination tablet (formulation 2) employs a sublingual and an oral route for systemic uptake. This tablet has an inner core of sildenafil with a polymeric time delay coating and an outer polymeric coating containing testosterone. It was designed to increase dosing practicality and decrease potential temporal non-adherence through circumventing the relatively complex temporal dosing scheme.

METHODS

Twelve healthy premenopausal subjects received both formulations randomly on separate days. Blood was sampled frequently to determine the pharmacokinetics of free testosterone, total testosterone, dihydrotestosterone, sildenafil and N-desmethyl-sildenafil.

RESULTS

Formulation 2 had a higher maximum concentration (Cmax ) for testosterone, 8.06 ng ml(-1) (95% confidence interval [CI] 6.84, 9.28) and higher area under the plasma concentration-time curve (AUC), 7.69 ng ml(-1)  h (95% CI 6.22, 9.16) than formulation 1, 5.66 ng ml(-1) (95% CI 4.63, 6.69) and 5.12 ng ml(-1)  h (95% CI 4.51, 5.73), respectively. Formulation 2 had a lower Cmax for sildenafil, 173 ng ml(-1) (95% CI 126, 220) and a lower AUC, 476 ng ml(-1)  h (95% CI 401, 551) than formulation 1, 268 ng ml(-1) (95% CI 188, 348) and 577 ng ml(-1)  h (95% CI 462, 692), respectively. Formulation 2 released sildenafil after 2.75 h (95% CI 2.40, 3.10).

CONCLUSIONS

The dual route/dual release fixed dose combination tablet fulfilled its design criteria and is considered suitable for further clinical testing.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

Female sexual interest/arousal disorder (FSIAD) is a significant problem impacting psychological well-being, but the pharmacotherapeutic options for this problem are lacking. The combined, on-demand, sublingual administration of low dose sublingual testosterone and oral administration of sildenafil is a novel pharmacotherapeutic option under development for FSIAD. In proof-of-concept trials, these compounds were successfully administered via different dosage forms (sublingual and oral) at different time points (separated by 2.5 h) because of their markedly different pharmacokinetic-pharmacodynamic profiles. For future larger scale studies and the clinical practice, this raises obvious adherence issues.

WHAT THIS STUDY ADDS

A newly developed dual route/dual release fixed dose combination tablet containing testosterone and sildenafil mimics the pharmacokinetic profile of these components when they are administered as different dosage forms, 2.5 h apart. This combination tablet is a suitable final pharmaceutical drug product that will be used in future studies.

Single dose testosterone administration alleviates gaze avoidance in women with Social Anxiety Disorder

Gaze avoidance is one of the most characteristic and persistent social features in people with Social Anxiety Disorder (SAD). It signals social submissiveness and hampers adequate social interactions. Patients with SAD typically show reduced testosterone levels, a hormone that facilitates socially dominant gaze behavior. Therefore we tested as a proof of principle whether single dose testosterone administration can reduce gaze avoidance in SAD. In a double-blind, within-subject design, 18 medication-free female participants with SAD and 19 female healthy control participants received a single dose of 0.5mg testosterone and a matched placebo, at two separate days. On each day, their spontaneous gaze behavior was recorded using eye-tracking, while they looked at angry, happy, and neutral facial expressions. Testosterone enhanced the percentage of first fixations to the eye-region in participants with SAD compared to healthy controls. In addition, SAD patients' initial gaze avoidance in the placebo condition was associated with more severe social anxiety symptoms and this relation was no longer present after testosterone administration. These findings indicate that single dose testosterone administration can alleviate gaze avoidance in SAD. They support theories on the dominance enhancing effects of testosterone and extend those by showing that effects are particularly strong in individuals featured by socially submissive behavior. The finding that this core characteristic of SAD can be directly influenced by single dose testosterone administration calls for future inquiry into the clinical utility of testosterone in the treatment of SAD.

Changes in spatial cognition and brain activity after a single dose of testosterone in healthy women

Studies have consistently shown that males perform better than females on several spatial tasks. Animal and human literature suggests that sex hormones have an important role in both establishing and maintaining this difference. The aim of the present study was to examine the effects of exogenous testosterone on spatial cognition and brain activity in healthy women. A cross-sectional, double-blind, randomized, placebo-controlled study was performed in 42 healthy young women who either received one dose of 0.5mg sublingual testosterone or placebo. They then learned a virtual environment and performed navigation tasks during functional magnetic resonance imaging (fMRI). Subsequently, their knowledge of the virtual environment, self-reported navigation strategy, and mental rotation abilities were measured. The testosterone group had improved representations of the directions within the environment and performed significantly better on the mental rotation task compared to the placebo group, but navigation success and navigation strategy were similar in the two groups. Nevertheless, the testosterone group had significantly increased activity within the medial temporal lobe during successful navigation compared to the placebo group, and a positive correlation between testosterone load and medial temporal lobe activity was found. Fetal testosterone levels, measured as second-to-fourth digit length ratio, interacted significantly with parahippocampal activity and tended towards giving higher mental rotation task scores. These results demonstrated that testosterone had a limited effect pertaining specifically to spatial cognition involving 3D-visualization in healthy women, while complex behaviors such as navigation, relying more on learned strategies, were not altered despite increased neuronal activity in relevant brain regions.

Testosterone biases the amygdala toward social threat approach

Testosterone enhances amygdala reactions to social threat, but it remains unclear whether this neuroendocrine mechanism is relevant for understanding its dominance-enhancing properties; namely, whether testosterone biases the human amygdala toward threat approach. This pharmacological functional magnetic-resonance imaging study shows that testosterone administration increases amygdala responses in healthy women during threat approach and decreases it during threat avoidance. These findings support and extend motivational salience models by offering a neuroendocrine mechanism of motivation-specific amygdala tuning.

Pharmacokinetics of a prototype formulation of sublingual testosterone and a buspirone tablet, versus an advanced combination tablet of testosterone and buspirone in healthy premenopausal women

The study aimed to compare the kinetics of two novel combination drug products for Female Sexual Interest/Arousal Disorder (FSIAD). Thirteen women received testosterone via the sublingual route followed 2.5 hours later by a buspirone tablet, versus a single combination tablet swallowed at once. The first clinical prototype consisted of a sublingual solution containing testosterone (0.5 mg) complexed with cyclodextrin and a tablet containing 10 mg buspirone, in a gelatin capsule to ensure blinding during the clinical studies. The innovative fixed-combination tablet consists of an inner-core component of 10 mg buspirone coated with a polymeric time-delay coating and an outer polymeric coating containing testosterone with hydroxypropyl-beta cyclodextrin. We observed an immediate testosterone pulse absorption from both formulations. We also demonstrated that there was adequate absorption of buspirone (>80 % relative to the conventional tablet) and a time delay in release of buspirone of 3.3 hours, close to the 3.0 hours of the reference formulation that showed clinical efficacy in early proof-of-principle studies. The newly developed combination tablet fulfils its design criteria and is a convenient tablet for further clinical studies in FSIAD.

Testosterone rapidly increases neural reactivity to threat in healthy men: a novel two-step pharmacological challenge paradigm

BACKGROUND

Previous research suggests that testosterone (T) plays a key role in shaping competitive and aggressive behavior in humans, possibly by modulating threat-related neural circuitry. However, this research has been limited by the use of T augmentation that fails to account for baseline differences and has been conducted exclusively in women. Thus, the extent to which normal physiologic concentrations of T affect threat-related brain function in men remains unknown.

METHODS

In the current study, we use a novel two-step pharmacologic challenge protocol to overcome these limitations and to evaluate causal modulation of threat- and aggression-related neural circuits by T in healthy young men (n = 16). First, we controlled for baseline differences in T through administration of a gonadotropin releasing hormone antagonist. Once a common baseline was established across participants, we then administered T to within the normal physiologic range. During this second step of the protocol we acquired functional neuroimaging data to examine the impact of T augmentation on neural circuitry supporting threat and aggression.

RESULTS

Gonadotropin releasing hormone antagonism successfully reduced circulating concentrations of T and brought subjects to a common baseline. Administration of T rapidly increased circulating T concentrations and was associated with heightened reactivity of the amygdala, hypothalamus, and periaqueductal grey to angry facial expressions.

CONCLUSIONS

These findings provide novel causal evidence that T rapidly potentiates the response of neural circuits mediating threat processing and aggressive behavior in men.

Testosterone administration in women increases amygdala responses to fearful and happy faces

Data from both rodents and humans show that testosterone reduces fear. This effect is hypothesized to result from testosterone's down regulating effects on the amygdala, a key region in the detection of threat and instigator of fight-or-flight behavior. However, neuroimaging studies employing testosterone administration in humans have consistently shown increased amygdala responsivity. Yet, no study to date has investigated specifically how testosterone affects the amygdala response to fearful emotional expressions. Such stimuli signal the presence of environmental threat and elicit robust amygdala responses that have consistently been associated with anxious traits. In the present study, we therefore used functional magnetic resonance imaging combined with a single administration of 0.5mg testosterone in 12 healthy women to assess testosterone's effects on amygdala responses to dynamic fearful (and happy control) faces. Our results show that both stimuli activate the amygdala. Notably, testosterone increased the amygdala response to both stimuli, and to an equal degree. Thus, testosterone appears not to reduce fear by attenuating the amygdala response toward signals of threat. Data further show that testosterone selectively increases activation of the superficial amygdala (SFA) and, to a lesser extent, the basolateral amygdala (BLA). No effect was found in the central nucleus, which is involved in the generation of autonomic fear responses. Both the SFA and BLA are considered input regions, and enhanced activation by testosterone might reflect the role of this hormone in adaptive responding to socially relevant stimuli. Furthermore, literature on the distinct roles of the SFA and BLA in fear processing show that increased activation of these subregions of the amygdala is consistent with a fear reducing effect of testosterone.

Pharmacokinetics of testosterone and estradiol gel preparations in healthy young men

The paucity of pharmacokinetic data on testosterone gel formulations and absence of such data on estradiol administration in healthy young men constitutes a fundamental gap of knowledge in behavioral endocrinological research. We addressed this issue in a double-blind and placebo controlled study in which we applied a topical gel containing either 150mg of testosterone (N=10), 2mg of estradiol (N=8) or a respective placebo (N=10) to 28 healthy young men. We then assessed serum concentrations of estradiol and testosterone in one hour intervals up to seven hours after drug application, measured LH, SHBG and cortisol levels once at baseline and three, four as well as six hours after gel administration. Treatment with testosterone gel resulted in maximum total serum testosterone concentration three hours after administration and did not suppress LH, cortisol and SHBG levels at any time point. Administration of estradiol gel led to maximum estradiol serum concentration two hours after administration. There was no suppression of cortisol, SHBG and absolute LH levels. We report here, for the first time, pharmacokinetic data on both high dose testosterone and estradiol gel application in healthy young males. The proposed model will assist in the design of future studies that seek to establish causality between testosterone and estradiol gel administration and behavioral as well as neurophysiological effects.