Gender differences and dose proportionality in the toxicokinetics of udenafil and its active metabolite following oral administration in rodents

Udenafil is a long-acting oral phosphodiesterase type 5 inhibitor used to treat erectile dysfunction which may also have beneficial effects on cardiovascular diseases. Udenafil is mainly biotransformed to the active metabolite N-dealkylated udenafil via cytochrome P450 3A. The aim of this study was to investigate the gender differences and dose proportionality of the toxicokinetics of udenafil and its metabolite N-dealkylated udenafil in rodents. Udenafil was administered orally by gavage to male and female B6C3F1/N mice (100, 240, 350, and 500 mg/kg) and F344 rats (60, 120, and 240 mg/kg). Plasma concentrations of udenafil and N-dealkylated udenafil were simultaneous measured via liquid chromatography-tandem mass spectrometry. Female mice showed higher systemic exposure to udenafil than male mice, whereas female rats showed lower systemic exposure to udenafil than male rats after repeated administration at high dose. Systemic exposure to the metabolite, N-dealkylated udenafil, was lower in female than male mice and rats. A dose proportionality assessment by power model revealed a lack of dose proportionality in systemic exposure (C_max, AUC_24h and AUC_inf) after administration of 100-500 mg/kg of udenafil in mice and 60-240 mg/kg in rats. This study thus demonstrates gender and species differences with regard to the toxicokinetic profiles of udenafil and its active metabolite N-dealkylated udenafil after oral administration of udenafil to mice and rats of both sexes. Our findings suggest the possibility of gender differences in the toxicokinetics of udenafil in humans and suggests that further study is needed in this cohort.

Ultra-high performance liquid chromatography-MS/MS (UHPLC-MS/MS) in practice: analysis of drugs and pharmaceutical formulations

Background

UHPLC-MS/MS is connected in various research facilities for the qualitative and quantitative investigation of a pharmaceutical substance, pharmaceutical items, and biological specimen.

Main body

The commence review article is an endeavor to offer pervasive awareness around assorted aspects and details about the UHPLC-MS/MS and related techniques with the aim on practice to an estimation of medicinal active agents in the last 10 years. The article also focused on isolation, separation, and characterization of present impurity in drug and biological samples.

Conclusion

Review article compiles a general overview of medicinally important drugs and their analysis with UHPLC-MS/MS. It gives fundamental thought regarding applications of UHPLC-MS/MS for the study on safety limit. The summary of developed UHPLC-MS/MS methods gives a contribution to the future trend and limitations in this area of research.

The Effect of Age on the Pharmacokinetics of Udenafil in Healthy Subjects

Udenafil, a cyclic guanosine monophosphate-specific phosphodiesterase type 5 inhibitor, has been developed to treat erectile dysfunction. We evaluated the effect of age on the pharmacokinetics and tolerability of udenafil. A single-center, open-label, parallel-group phase 1 study was conducted in healthy adult subjects who took a single oral dose of udenafil (100 mg). The pharmacokinetics and tolerability of udenafil were compared between 12 healthy young men (21-27 years) and 12 healthy elderly men (65-78 years). Serial blood and urine samples were collected for up to 60 and 48 hours after dosing. The plasma concentrations of udenafil and its major metabolite, DA-8164, were analyzed using a validated liquid chromatography-tandem mass spectrometry method. The mean C_max of udenafil tended to be slightly less (214.0 vs 292.8 μg/L) in the elderly compared with the young (GMR, 68.9; 95% CI, 48.9-97.1); however, the AUC did not differ between the groups (1858.8 vs 2100.6 μg·h/L; GMR, 84.6; 95% CI, 66.1-108.4). The mean t_1/2 was prolonged by approximately 5 hours in the elderly (P < .05). The clearance and metabolic AUC ratio did not differ between the elderly and young. In terms of tolerability, all adverse events were mild, and all subjects recovered without additional therapy. The systemic exposure of elderly subjects to udenafil appears to be comparable to or slightly less than that of young healthy subjects. Based on our pharmacokinetic comparisons, udenafil dose adjustment is unlikely to be required in the elderly population.

A review of analytical methods for the determination of four new phosphodiesterase type 5 inhibitors in biological samples and pharmaceutical preparations

The introduction of oral phosphodiesterase type 5 inhibitor therapy in 1998 revolutionized the treatment of erectile dysfunction. Erectile dysfunction is the most common sexual problem in men. It often has a profound effect on intimate relationships and quality of life. The analysis of pharmaceuticals is an important part of the drug development process as well as for routine analysis and quality control of commercial formulations. Whereas the determination of sildenafil citrate, vardenafil and tadalafil are well documented by a variety of methods, there are few publications about the determination of udenafil, lodenafil carbonate, mirodenafil and avanafil. The paper presents a brief review of the action mechanism, adverse effects, pharmacokinetics and the most recent analytical methods that can determine drug concentration in biological matrices and pharmaceutical formulations of these four drugs.

Development of udenafil-loaded microemulsions for intranasal delivery: in vitro and in vivo evaluations

To achieve rapid onset of action and improved bioavailability of udenafil, a microemulsion system was developed for its intranasal delivery. Phase behavior, particle size, transmission electron microscope (TEM) images, and the drug solubilization capacity of the microemulsion were investigated. A single isotropic region was found in pseudo-ternary phase diagrams developed at various ratios with CapMul MCM L8 as an oil, Labrasol as a surfactant, and Transcutol or its mixture with ethanol (1:0.25, v/v) as a cosurfactant. Optimized microemulsion formulations with a mean diameter of 120-154 nm achieved enhanced solubility of udenafil (>10mg/ml) compared with its aqueous solubility (0.02 mg/ml). An in vitro permeation study was performed in human nasal epithelial (HNE) cell monolayers cultured by the air-liquid interface (ALI) method, and the permeated amounts of udenafil increased up to 3.41-fold versus that of pure udenafil. According to the results of an in vivo pharmacokinetic study in rats, intranasal administration of udenafil-loaded microemulsion had a shorter T(max) value (1 min) compared with oral administration and improved bioavailability (85.71%) compared with oral and intranasal (solution) administration. The microemulsion system developed for intranasal administration may be a promising delivery system of udenafil, with a rapid onset of action and improved bioavailability.