Subacute toxicities and toxicokinetics of DA-8159, a new phosphodiesterase type V inhibitor, after single and 4-Week repeated oral administration in rats

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.

Udenafil, a Phosphodiesterase 5 Inhibitor, Reduces Body Weight in High-Fat-Fed Mice

Purpose

High-fat (HF) feeding induces hypothalamic leptin resistance via the activation of toll-like receptor 4 (TLR4). TLR4 deficiency confers resistance to diet-induced obesity. Udenafil, an anti-impotence drug, inhibits TLR4 in airway epithelial cells in vitro. In this study, we evaluated whether udenafil suppressed the hypothalamic expression of TLR4 and reduced body weight.

Materials and Methods

The hypothalamic expression of TLR4, phosphodiesterase 5 (PDE5), nuclear factor-κB (NF-κB), and myeloid differentiation primary response gene 88 (Myd88) was analyzed by real-time polymerase chain reaction after treating mice for 2 days with udenafil (0, 12, 120, or 600 µg/d). Furthermore, the hypothalamic expression of TLR4, pro-opiomelanocortin (POMC), and neuropeptide Y (NPY) was analyzed after 9 days' treatment with udenafil and/or leptin. We also measured body weight and food intake following 9 days of udenafil and/or leptin treatment in control- and HF-fed mice.

Results

Udenafil suppressed hypothalamic TLR4 mRNA expression dose-dependently. The changes were associated with decreased PDE5, NF-κB, and Myd88 expression. Udenafil treatment for 9 days reduced body weight and caloric intake in HF-fed mice. This may have been associated with the suppression of NPY expression that was elevated by HF feeding. POMC expression was not affected by udenafil. However, udenafil did not augment the effects of leptin on the reduction of body weight and caloric intake in HF-fed mice.

Conclusions

These results suggested that udenafil reduced body weight by suppressing hypothalamic TLR4 mRNA expression in HF-fed mice and the combination effect of udenafil and leptin was additive rather than synergistic.

Long-Term Follow-Up of Lymphatic Malformations in Children Treated with Sildenafil

BACKGROUND/OBJECTIVES

Lymphatic malformations (LMs) are challenging to treat. Reports on the benefits of sildenafil for LM management have been mixed. This study evaluated long-term clinical outcomes of pediatric LM patients after sildenafil treatment.

METHODS

A retrospective chart review was performed on pediatric LM patients treated with sildenafil in the past 5 years. Patients were also contacted to complete a survey of comprehensive questions about their LM after sildenafil and subsequent interventions.

RESULTS

Of 12 patients identified, 10 (83.3%) participated in the follow-up survey. The average age was 8 years (range 4-16 yrs), median treatment duration was 9 months, and the average time of follow-up after sildenafil was 4 years; one patient is still taking sildenafil. Ten patients surveyed (83.3%) reported positive therapeutic response, with improvement in the size and compressibility of their LM during posttreatment clinical visits. Six received additional interventions (four sirolimus, one sclerotherapy, one surgery) after sildenafil was discontinued, with all but one reporting a positive response to subsequent interventions. Minor side effects at the time of sildenafil treatment included mild flushing, dizziness, and transient nausea, but no adverse effects were reported at the long-term follow-up.

CONCLUSION

This is the first report of long-term follow-up of pediatric LM patients treated with sildenafil. Our findings suggest that sildenafil is beneficial for the symptomatic treatment of LMs. Additional analysis on the role of sildenafil as adjuvant therapy is necessary to optimize the use of this medication in the management of complex LMs.

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.

Relation between statistics and treatment-related changes obtained from toxicity studies in rats: if detected a significant difference in low or middle dose for quantitative values, this change is considered as incidental change?

The purpose of a toxicity test is to determine the no-observed-effect level (NOEL) of test substance through biological and pharmacological techniques. If the low dose not does show statistically significant and biologically relevant changes in the data evaluated in a study, the usual practice is to consider this dose as the NOEL. To overcome this, 6 types of techniques that seemed to be appropriate are presented in this paper by investigating the results of several domestic and foreign theses on toxicology. The most appropriate techniques appear to be the trend test, comparison between treatment group and historical control by t-test, and confirmation that all individual values lie within the 95% confidence interval (2 SD) of the historical control value, if a significant difference is admitted in the low dose.

Circulating endothelial progenitor cells and endothelial function after chronic Tadalafil treatment in subjects with erectile dysfunction

We evaluated the effect of a chronic treatment with Tadalafil on progenitor cells (PCs) number and endothelial function in patients with erectile dysfunction (ED) with or without cardiovascular risk factors. Twenty-six subjects with ED and 23 aged matched controls were studied. All subjects underwent blood tests, International Index of Erectile Function (IIEF-5), Nocturnal Penile Tumescence Rigidity Monitoring test (NPTRM), brachial artery flow-mediated dilation (FMD) and PCs count. International index of erectile function, FMD and PC count were re-evaluated in all subjects at the end of Tadalafil and placebo treatment. With respect to controls patients had lower basal FMD (P < 0.05) and basal PCs (P < 0.05). Treatment with Tadalafil determined a significant increase in PCs (P < 0.001) and FMD (P < 0.001) with respect to basal level. Positive correlation was found between basal FMD and PCs (P < 0.05) and between basal FMD and PCs increase after Tadalafil treatment (P < 0.05). Tadalafil promotes a mobilization of PCs and improves endothelial function in ED patients.

PDE-5 inhibitor, Vardenafil, increases circulating progenitor cells in humans

Bone marrow-derived endothelial progenitor cells (EPCs) originate from haematopoietic stem cells in bone marrow and migrate into the peripheral circulation to promote endothelial repair and neovascularization. The number of circulating progenitor cells is reduced in patients with cardiovascular risk factor. The aim of our study was to determine the number of these cells in healthy patients and to evaluate the effect of Vardenfil, a phosphodiesterases-5 (PDE-5) inhibitor, in the number of circulating EPCs. In our study, we found a significant increase in the number of these cells after the drug administration.