Polyamidoamine (PAMAM) dendrimers as potential release modulators and oral bioavailability enhancers of vardenafil hydrochloride.

Vardenafil hydrochloride (VAR) is an erectile dysfunction treating drug. VAR has a short elimination half-life (4-5 h) and suffers low oral bioavailability (15%). This work aimed to explore the dual potential of VAR-dendrimer complexes as drug release modulators and oral bioavailability enhancers. VAR-dendrimer complexes were prepared by solvent evaporation technique using four dendrimer generations (G4.5, G5, G5.5 and G6) at three concentrations (190 nM, 380 nM and 950 nM). The systems were evaluated for intermolecular interactions, particle size, zeta potential, drug entrapment efficiency percentages (EE%) and drug released percentages after 2 h (Q2h) and 24 h (Q24h). The results were statistically analyzed, and the system showing the highest desirability was selected for further pharmacokinetic studies in rabbits, in comparison to Levitra® tablets. The highest desirability (0.82) was achieved with D10 system comprising VAR (10 mg) and G6 (190 nM). It possessed small particle size (113.85 nm), low PDI (0.19), positive zeta potential (+21.53), high EE% (75.24%), promising Q2 h (41.45%) and Q24 h (74.05%). Compared to Levitra® tablets, the significantly (p < 0.01) delayed Tmax, prolonged MRT(0-∞) and higher relative bioavailability (3.7-fold) could clarify the dual potential of D10 as a sustained release system capable of enhancing VAR oral bioavailability.

Lipomers (Lipid-polymer Hybrid Particles) of Vardenafil Hydrochloride: a Promising Dual Platform for Modifying the Drug Release Rate and Enhancing Its Oral Bioavailability.

Vardenafil hydrochloride is commonly used for the curing of erectile dysfunction. VAR suffers certain limitations: (i) short elimination half-life (4-5 h), (ii) low aqueous solubility (0.11 mg/mL), (iii) susceptibility to extensive first-pass metabolism and drug efflux transporters (P-glycoprotein), and (iv) limited (15%) oral bioavailability. The current study focused on the development of VAR lipomers as promising modified release systems able to enhance oral bioavailability. VAR-lipomers (lipid-polymer complexes) were successfully developed by a modified precipitation technique employing a lipid (polyglyceryl-6-distearate or glyceryl tristearate) and an amphiphilic polymer (Gantrez®). Three VAR:lipid ratios [1:1, 1:2, and 1:3] and three VAR:Gantrez® ratios [4:1, 2:1, and 1:1] were investigated. Solid-state characterization studies involved differential scanning calorimetry (DSC), X-ray diffraction (XRD), and Fourier-transform infrared (FT-IR) spectroscopy. The systems were assessed for particle size, polydispersity index (PDI), zeta-potential, VAR entrapment-efficiency (EE%), morphology, and VAR released % after 2 h (Q2h) and 8 h (Q8h). The best-achieved system (the highest desirability) was promoted for pharmacokinetic studies in fasted rabbits. Statistical analysis of data revealed that L9 system (PGDS, VAR, and Gantrez®; 3:1:1, respectively) had the highest desirability (0.85) with respect to spherical particle size (622.15 nm), PDI (0.11), zeta-potential (-27.90 mV), EE% (62.80%), Q2h (43.45%), and Q8h (77.40%). With respect to Levitra® tablets, the significantly higher relative bioavailability (170%), delayed Tmax, and extended MRT(0-∞) clarified the dual ability of L9 system. Lipomers are emerging systems capable of modifying the rate of VAR release and promoting its oral bioavailability.

Comparison of Pharmacokinetics of Vardenafil Administered Using an Ultrasonic Nebulizer for Inhalation vs a Single 10-mg Oral Tablet.

INTRODUCTION: Delivery of vardenafil (for improvement of erectile function) via the inhaled route of administration may be advantageous in that this avoids extensive first pass metabolism and may therefore increase the bioavailability (hence the reliability of absorption) and shorten the time of pharmacological onset of activity. A unique nebulizer design has been developed by the sponsor (Advanced Medical Institute Pty Ltd) that is capable of delivering relatively large volumes of drug. AIM: The primary objective of the Phase 1 study was to assess and compare the pharmacokinetics of a single dose of vardenafil 10-mg tablet and a single dose of vardenafil solution administered via inhalation using an ultrasonic nebulizer device. Secondary objective was to assess the safety of vardenafil administered via inhalation using an ultrasonic nebuliser device. METHODS: Two-part study in healthy volunteers. Dose-ranging study was performed in two subjects to determine the appropriate inhalational dose, followed by an open, randomized, crossover, single dose pharmacokinetic study in 12 subjects, which compared a single 10-mg oral dose to the inhalation dose. MAIN OUTCOME MEASURES: Cmax, Cmax/Dose, Tmax, ke, t1/2, AUC0-t, AUCt-∞, AUC0-∞, AUC0-∞, AUC0-∞/Dose, and % area extrapolated. RESULTS: The two treatments are not bioequivalent, with vardenafil absorbed and eliminated faster and with less variability using the nebulizer for drug delivery. Administration via the inhalational route was not associated with any clinically significant changes in blood pressure or heart rate, and no serious adverse events were recorded, demonstrating an acceptable safety profile. CONCLUSION: To our knowledge, this is the first report of the administration of vardenafil HCl via the pulmonary route of administration. This trial demonstrates that vardenafil HCl may be administered using the ultrasonic nebulizer to reach blood levels comparable with those produced by a vardenafil 10-mg oral tablet, faster and using less drug. This new route of administration may potentially improve the onset of action, reliability, and safety for this class of drug.

Pharmacokinetics and Bioequivalence of Vardenafil Hydrochloride in Healthy Chinese Volunteers.

Vardenafil hydrochloride tablet is an inhibitor of phosphodiesterase type 5, primarily for the treatment of erectile dysfunction. This postprandial study evaluated the pharmacokinetics and bioequivalence of the test and reference formulations of vardenafil hydrochloride tablets in healthy Chinese volunteers. An open, randomized, single-center, single-dose, 2-period, 2-sequence bioequivalence test was conducted on 66 healthy subjects under fed conditions. Subjects were randomly assigned to a 20-mg test or reference formulation with a 7-day washout period. Venous blood samples (4 mL) were collected from each subject 25 times spanning predose (0 hour) to 24 hours after dosing. The plasma concentration of vardenafil was determined by high-performance liquid chromatography-tandem mass spectrometry. Sixty-two volunteers completed the study. Under fed conditions, the maximum plasma concentration was 29.1 ng/mL, the area under the concentration-time curve (AUC) from time 0 to the time of the last measurable concentration was 85.3 ng•h/mL, and AUC from time 0 to infinity was 87.1 ng•h/mL. The 90% confidence intervals of the geometric mean ratio of AUC time 0 to the time of the last measurable concentration and AUC from time 0 to infinity were within the bioequivalence acceptance range of 0.80-1.25. The test formulation was a bioequivalent alternative to the reference formulation when taken under fed conditions in healthy Chinese subjects.

Ethosome-Derived Invasomes as a Potential Transdermal Delivery System for Vardenafil Hydrochloride: Development, Optimization and Application of Physiologically Based Pharmacokinetic Modeling in Adults and Geriatrics.

AIM: The aim of the current work was to develop vardenafil hydrochloride (VRD)-loaded ethosome-derived invasomes as a possible transdermal system which could be used for patients suffering from pulmonary arterial hypertension. METHODS: VRD-loaded ethosomes were developed at three concentrations of phosphatidylcholine (5, 10 and 15 mg/mL) and three percentages of ethanol (20%, 30% and 40%, v/v). The best achieved VRD-loaded ethosomes (ETH9) were optimized to invasomes via incorporation of terpenes (limonene, cineole and a 1:1 mixture) at three concentrations (0.5%, 1% and 2%, v/v). All systems were evaluated for vesicle size, zeta potential, drug entrapment efficiency (EE%), cumulative drug permeated percentages after 0.5hrs (Q0.5h) and 12hrs (Q12h) and steady-state flux (Jss). The optimized system (ETH9-INV8) was further characterized for morphology, histopathology and confocal laser scanning microscopy (CLSM). Physiologically based pharmacokinetic (PBPK) modeling was employed to estimate VRD pharmacokinetic parameters from the optimized transdermal system and an oral aqueous drug dispersion, in adults and geriatrics. RESULTS: The optimized invasomal system (ETH9-INV8) was characterized with spherical vesicles (159.9 nm) possessing negative zeta potential (-20.3 mV), promising EE% (81.3%), low Q0.5h (25.4%), high Q12h (85.3%) and the largest steady-state flux (6.4 µg.cm-2h-1). Following a leave-on period of 12hrs in rats, it showed minor histopathologic changes. CLSM studies proved its ability to deeply permeate rat skin. Lower Cmax values, delayed Tmax estimates and greater AUC0-24h folds in adults and geriatrics (≈ 2.18 and 1.69, respectively) were estimated following the transdermal application of ETH9-INV8 system. CONCLUSION: ETH9-INV8 is a promising transdermal system for VRD.

The first-generation phosphodiesterase 5 inhibitors and their pharmacokinetic issue.

BACKGROUND: Erectile dysfunction (ED) is a relatively frequent disease that negatively impacts the overall quality of life, well-being, and relationships. Although the use of phosphodiesterase 5 inhibitors (PDE5is) has revolutionized the treatment of ED, a high percentage of ED patients discontinue PDE5i treatment. OBJECTIVES: (i) To analyze the reasons for patient dissatisfaction leading to PDE5i discontinuation; (ii) analyze the pharmacokinetics of new formulations focusing on the time needed to reach an effective plasma concentration of PDE5is (Tonset ) following drug intake; and (iii) summarize the physicochemical properties of sildenafil to understand which excipients may increase the absorption rate. MATERIAL AND METHODS: An online PubMed literature search was conducted to identify English language publications from inception to January 2019. RESULTS: The main reasons for patient dissatisfaction when using PDE5is on demand are the relatively long Tonset after taking vardenafil and sildenafil, including formulations such as film-coated tablets, fine granules, orally disintegrating tablets (ODTs), and oral thin films (ODFs). The relatively long Tonset , further worsened when accompanied by eating, highlights the following: (i) the need for planning intercourse, determining partner-related issues; (ii) issues when having sex before the maximum effect of the drug; and (iii) lower drug-related placebo effects. Some data suggest that sildenafil is a 'difficult' molecule, but Tonset can be improved following absorption by buccal mucosa using appropriate excipients. CONCLUSIONS: We conclude that several ODT and ODF formulations can improve the 'discretion' issue because they are taken without water, but they have similar pharmacokinetics to corresponding film-coated tablet formulations. One ODF formulation of sildenafil was characterized by a shorter Tonset and could potentially increase patient satisfaction following treatment. However, more clinical studies are needed to confirm the findings. Surfactants and ascorbic acid appear to be crucial excipients for achieving a high absorption rate, but more studies are needed.

Development and single dose clinical pharmacokinetics investigation of novel zein assisted- alpha lipoic acid nanoencapsulation of vardenafil.

The aim of this study was to utilize the biocompatibility of the natural ingredients zein and alpha lipoic acid (ALA) as a novel nanosphere matrix formulation that encapsulates vardenafil (VRD) for improved drug delivery and bioavailability. Three formulations were prepared using zein: ALA ratio of 1:1, 2:1 and 3:1 by liquid-liquid phase separation method. Physicochemical characterization and in vitro diffusion evaluation were carried out for the prepared formulations. A single dose clinical pharmacokinetic study was carried out for the selected formulation. Results revealed VRD formulations showed particle size of 836.7 ± 191.3, 179.8 ± 18.4 and 147.3 ± 18.1 nm and encapsulation efficiency of 55.72 ± 4.36, 65.33 ± 7.82 and 69.38 ± 6.83% for F1, F2 and F3, respectively. Single dose clinical pharmacokinetic results, in healthy human volunteers, showed improved VRD bioavailability by 2.5 folds from nanosphere formula (F3) compared with the marketed tablets. The formulation of novel zein-ALA nanospheres offers the possibility for application of a biocompatible nano-carrier system in drug delivery for improved drug delivery and efficacy.

Preparation and characterization of intravaginal vardenafil suppositories targeting a complementary treatment to boost in vitro fertilization process.

Vaginal route has been recently considered as a potential route for systemic delivery of drugs with poor oral bioavailability. Vardenafil (VDF) is a relatively new phosphodiesterase-5 inhibitor that exhibits a limited oral bioavailability (≈15%) due to extensive first-pass metabolism. In this study, we attempted to enhance the systemic bioavailability of VDF via its formulation within vaginal suppositories. Witepsol H15 and Suppocire NA50 were adopted as lipophilic suppository bases while polyethylene glycol 4000/400 and glycerogelatin were used as hydrophilic suppository bases. The effect of different base types and/or the incorporation of bioadhesive polymer on in vitro release of VDF were evaluated. The in vivo fate and organ biodistribution of VDF following intravaginal (IVG) administration were also investigated. VDF release from water-soluble bases was higher than that from lipophilic bases. The incorporation of bioadhesive polymers, such as Na alginate, remarkably sustained drug release from suppository base. The organ biodistribution study showed a higher Cmax (32 times) and AUC0-4h (20 times) of VDF in uterus following IVG administration of conventional suppositories, compared to oral administration of VDF suspension. In addition, cyclic guanosine monophosphate (cGMP) serum levels, used as an indicator of the in vivo activity of VDF, in animals were higher following IVG administration rather than oral administration. This study suggests that IVG administration of VDF might represent a potential alternative to oral route with superior therapeutic benefits especially when targeting the uterus.

Labelling, molecular modelling and biological evaluation of vardenafil: a potential agent for diagnostic evaluation of erectile dysfunction.

99mTc-tricarbonyl-vardenafil was specifically radiosynthesized for diagnostic evaluation of erectile dysfunction with a radiochemical yield ~97.2%. It was stable in saline up to 15h and in serum for more than 6h. The radiocomplex was lipophilic with a partition coefficient ~1.32 and plasma protein binding 72-76%. Its structure was determined using molecular mechanics and confirmed by NMR. In-silico docking to its target PDE5 enzyme was performed. The radiocomplex inhibitory activity was assessed and its IC50 was 0.7nM. Biodistribution in normal rats and biological evaluation in rat models of erectile dysfunction were performed. The results strongly suggested that 99mTc-tricarbonyl-vardenafil is a good candidate to image erectile dysfunction in humans.

Nanoethosomal transdermal delivery of vardenafil for treatment of erectile dysfunction: optimization, characterization, and in vivo evaluation.

Vesicular drug delivery systems have recently gained attention as a way of improving dosing accuracy for drugs with poor transdermal permeation. The current study focuses on utilization of the natural biocompatible vesicles to formulate vardenafil nanoethosomes (VRD-NE), for the enhancement of their transdermal permeation and bioavailability. Fifteen formulations were prepared by thin-layer evaporation technique according to Box-Behnken design to optimize formulation variables. The effects of lipid composition, sonication time, and ethanol concentration on particle size and encapsulation efficiency were studied. The diffusion of vardenafil (VRD) from the prepared nanoethosomes specified by the design was carried out using automated Franz diffusion cell apparatus. The optimized formula was investigated for in vivo pharmacokinetic parameters compared with oral VRD suspension. Confocal laser scanning microscopy images were used to confirm enhanced diffusion release of VRD in rat skin. The results showed that the optimized formula produced nanoethosomes with an average size of 128 nm and an entrapment efficiency of 76.23%. VRD-NE provided a significant improvement in permeation with an enhancement ratio of 3.05-fold for a film made with optimally formulated VRD-NE compared with a film made with VRD powder. The transdermal bioavailability of VRD from the nanoethosome film was approximately twofold higher than the oral bioavailability from an aqueous suspension. VRD-NE thus provide a promising transdermal drug delivery system. As a result, management of impotence for a longer duration could be achieved with a reduced dosage rate that improves patient tolerability and compliance for the treatment of erectile dysfunction.

PDE5 inhibition improves acquisition processes after learning via a central mechanism.

In previous studies, we have shown that phosphodiesterase type 5 inhibitors (PDE5-Is) can improve early consolidation of object memory. These conclusions were based on the timing of drug administration relative to the learning trial (i.e. before or after). However, there are very little pharmacological data available about the pharmacokinetic profile of orally administered PDE5-Is in the rat. Furthermore, there is still debate whether these effects are achieved via central or peripheral mechanisms and if acquisition processes are improved. In the current study, we tested the effects of the PDE5-I vardenafil in a cholinergic-deficit model and compared the effects after intracerebroventricular (ICV) versus oral (PO) administration. We found that PO vardenafil restored a scopolamine-induced memory impairment when dosed within 2 min after the learning trial while ICV vardenafil was able to restore memory when injected within 4 min after learning. Because the test trial was within 10 min after the learning trial, this suggests that these effects on object memory are related to acquisition processes that may still be ongoing in a time window after the learning trial. To further elucidate the extent of this acquisition window, we investigated the pharmacokinetic profile of vardenafil after PO administration where it was detected within 4 min post-dose. Taken together, our data suggest that PDE5 is involved in acquisition processes, which may linger for at least 4-6 min after learning. Further studies are needed to exclude that these effects could also be explained on basis of an effect on early consolidation processes. Additionally, the effectiveness of ICV-administered vardenafil provides further experimental evidence that PDE5-Is improve memory via a central mechanism.