Syed Tabrez Ali, Nabeeh I Rakkah.
Possible neurogenic role of Sildenafil citrate (Viagra) on the regulatory pattern of pituitary-testis axis in diabetic males with and without neuropathy.
Pak J Pharmacol Jan ;24(1):25-35.

Sexual dysfunctions due to neurogenic impotence decrease the testosterone levels through a central effect on the hypothalamic-pituitary axis. The present study deals with the effect of sildenafil citrate (Viagra) treatment for these neurogenic sexual disturbances on the reversibility of this neuro-endocrine pattern of the serum levels of pituitary-gonadal hormones. In this investigation 50 insulin dependent (IDDM) and 50 non insulin dependent (NIDDM) diabetic male patients with and without an objective evidence of neuropathy and 50 age matched non diabetic male controls were selected. Every male had age between 20 to 65 years with duration of diabetes distributed over 1 to 20 years. During treatment with sildenafil citrate (50 mg. oral dose) serum total testosterone, free testosterone, serum PRL, FSH and LH were measured. Treatment with 50 mg. of oral sildenafil citrate reversed this neuro-endocrine release pattern in both IDDM/ NIDDM neuropathic men by exhibiting a significant increase in serum total and serum free (urinary) testosterone levels (p<0.001) and a significant decrease in the levels of serum prolactin (PRL) and follicle stimulating hormone (FSH). Decrease in luteinizing hormone (LH) was found to be less significant (p<0.01). However both types of non neuropathic diabetics treated with sildenafil citrate showed a non significant difference in the in the serum levels of the above mentioned pituitary-gonadal hormones when compared with the untreated groups and their respective control subjects. These findings conclude that sildenafil citrate has a direct effect on the pituitary-testicular axis and is a well tolerated and highly effective oral therapy for restoring the potency with established neuropathic cause (irrespective of the type of diabetes) and may represent a new class of autonomically acting drug for the treatment of this condition. In other words it is worth trying sildenafil citrate for erectile dysfunctions of neuropathic etiology.

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