financial constraints

Exogenously administered testosterone will override the normal negative feedback of endogenous testosterone on the hypothalamus and pituitary. Constantly, relatively high and constant testosterone levels will cause a drop in FSH and LH production by the pituitary. Since FSH and LH are signalling hormones to the testes, endogenous testosterone production and spermatogenesis will be down-regulated. It is expected that intranasal dosing in the morning will mimic the normal physiological pattern of testosterone production thereby avoiding negative side-effects on spermatogenesis. Trans-dermal gels give testosterone levels more or less constant over the day and will very likely have inhibitory effects on spermatogenesis.

The main objective of this study is to show that twice daily intranasal dosing does not have, or has a smaller inhibitory effect on spermatogenesis in comparison to transdermal testosterone gels.

Inclusion Criteria:

• Age greater than or equal to 50 years but not older than 80 years of age;
• Serum testosterone level <13.8 nmol/l;
• Sperm concentration > 40 Million/ml;
• Willing to give written informed consent.

Exclusion Criteria:

• Testicular diseases or having had any surgical procedures applied to the testes;
• History or currently existing serious disease of any type, in particular liver, kidney or heart disease, any form of diabetes mellitus, cancer or psychiatric illness;
• Current androgen, anabolic steroid or sex hormone treatment or any treatment with such compounds in the previous 6 months;
• Blood donation within the 12-week period before the initial study dose.
• History of, or current nasal disorders (e.g. seasonal or perennial allergic rhinitis, atrophic rhinitis, polyposis, abuse of nasal decongestants, clinically relevant nasal septum deviation, recurrent epistaxis) or sleep apnea;
• Elevated serum PSA levels (> 4 ng/ml for subjects >= 50 years of age);