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miami797 · 28-05-2007, 04:57 PM

Article 1:
Injectable testosterone undecanoate has more favourable pharmacokinetics and pharmacodynamics than testosterone enanthate CJ Partsch, GF Weinbauer, R Fang, and E Nieschlag
Institute of Reproductive Medicine of the University, Munster, Germany.

Testosterone preparations producing constant physiological testosterone serum levels are desirable for long-term treatment of androgen deficiency. However, all injectable testosterone esters used clinically for substitution of male hypogonadism are characterized by unfavourable pharmacokinetics. We therefore tested two groups of five long-term orchidectomized cynomolgus monkeys (Macaca fascicularis), which received a single intramuscular injection of 10 mg/kg body weight of an injectable testosterone undecanoate (TU) preparation or testosterone enanthate (TE) in a preclinical study to assess the pharmacokinetic and pharmacodynamic characteristics of TU in comparison to TE. The dose was equivalent to 6.3 and 7.2 mg of pure testosterone per kilogram body weight in the TU and TE group, respectively. Following injection of TU, mean serum testosterone rose to 58 +/- 18 nmol/l on day 1 and remained at moderately supraphysiological levels of 40-68 nmol/l for 45 days. Thereafter, testosterone levels were maintained in the normal range of intact monkeys for another 56 days. The TE injection resulted in highly supraphysiological levels of 100-177 nmol/l from immediately after the injection to day 5. A rapid decline followed and testosterone levels reached the lower limit of normal after 31 days. Serum testosterone levels were significantly higher in the TE-than in the TU-treated animals on days 0.5-7 (p < 0.05). Significantly lower testosterone levels were seen in the TE than in the TU group on days 16, 22, 25 and 31 (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Article 2:
Repeated intramuscular injections of testosterone undecanoate for substitution therapy in hypogonadal men
Eberhard Nieschlag, Dorothee Büchter, Sigrid von Eckardstein, Katrin Abshagen, Manuela Simoni & Hermann M. Behre0Institute of Reproductive Medicine of the University, Münster, Germany
Correspondence to: Prof. Dr E. Nieschlag, Institute of Reproductive Medicine of the University, Domagkstr.11, D–48149 Münster, Germany. Fax: + 49 251835 6093; E-mail: nieschl@uni-muenster.de

OBJECTIVE
To investigate the suitability of intramuscular testosterone undecanoate (TU) injections for substitution therapy in hypogonadal men.

STUDY DESIGN
Clinical, open-label, non-randomized trial of 13 hypogonadal men receiving 4 intramuscular injections of 1000 mg TU in 4-ml castor oil at 6-week intervals. General wellbeing, sexual parameters, clinical chemistry, hormone levels, prostate size and prostate-specific antigen (PSA) were evaluated over 24 weeks and compared with baseline values.

RESULTS
Testosterone serum levels were never found below the lower limit of normal and only briefly after the 3rd and 4th injection above the upper limit of normal, while peak and trough values increased over the 24-week observation period. Oestradiol and dihydrotestosterone followed this pattern, not exceeding the normal limits. No serious side-effects were noted. Slight increases in body weight, haemoglobin, haematocrit, prostate volume and PSA, suppression of gonadotrophins as well as increased ejaculation frequency occurred as signs of adequate testosterone substitution.

CONCLUSION
Testosterone undecanoate is well tolerated by the patients. The injection intervals can be extended even beyond the 6-week periods chosen in the present study. Altogether, intramuscular testosterone undecanoate appears to be well suited for long-term substitution therapy in hypogonadism and hormonal male contraception

Links to these articles:
1. http://www.eje-online.org/cgi/conten...ract/132/4/514
2. http://www.blackwell-synergy.com/lin...5.1999.00881.x

28-05-2007, 04:57 PM	#1 (permalink)
miami797 Feeling Slutty Join Date: Feb 2004 Posts: 1,438	Undecanoate VS. Enanthate Article 1: Injectable testosterone undecanoate has more favourable pharmacokinetics and pharmacodynamics than testosterone enanthate CJ Partsch, GF Weinbauer, R Fang, and E Nieschlag Institute of Reproductive Medicine of the University, Munster, Germany. Testosterone preparations producing constant physiological testosterone serum levels are desirable for long-term treatment of androgen deficiency. However, all injectable testosterone esters used clinically for substitution of male hypogonadism are characterized by unfavourable pharmacokinetics. We therefore tested two groups of five long-term orchidectomized cynomolgus monkeys (Macaca fascicularis), which received a single intramuscular injection of 10 mg/kg body weight of an injectable testosterone undecanoate (TU) preparation or testosterone enanthate (TE) in a preclinical study to assess the pharmacokinetic and pharmacodynamic characteristics of TU in comparison to TE. The dose was equivalent to 6.3 and 7.2 mg of pure testosterone per kilogram body weight in the TU and TE group, respectively. Following injection of TU, mean serum testosterone rose to 58 +/- 18 nmol/l on day 1 and remained at moderately supraphysiological levels of 40-68 nmol/l for 45 days. Thereafter, testosterone levels were maintained in the normal range of intact monkeys for another 56 days. The TE injection resulted in highly supraphysiological levels of 100-177 nmol/l from immediately after the injection to day 5. A rapid decline followed and testosterone levels reached the lower limit of normal after 31 days. Serum testosterone levels were significantly higher in the TE-than in the TU-treated animals on days 0.5-7 (p < 0.05). Significantly lower testosterone levels were seen in the TE than in the TU group on days 16, 22, 25 and 31 (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS) Article 2: Repeated intramuscular injections of testosterone undecanoate for substitution therapy in hypogonadal men Eberhard Nieschlag, Dorothee Büchter, Sigrid von Eckardstein, Katrin Abshagen, Manuela Simoni & Hermann M. Behre0Institute of Reproductive Medicine of the University, Münster, Germany Correspondence to: Prof. Dr E. Nieschlag, Institute of Reproductive Medicine of the University, Domagkstr.11, D–48149 Münster, Germany. Fax: + 49 251835 6093; E-mail: nieschl@uni-muenster.de OBJECTIVE To investigate the suitability of intramuscular testosterone undecanoate (TU) injections for substitution therapy in hypogonadal men. STUDY DESIGN Clinical, open-label, non-randomized trial of 13 hypogonadal men receiving 4 intramuscular injections of 1000 mg TU in 4-ml castor oil at 6-week intervals. General wellbeing, sexual parameters, clinical chemistry, hormone levels, prostate size and prostate-specific antigen (PSA) were evaluated over 24 weeks and compared with baseline values. RESULTS Testosterone serum levels were never found below the lower limit of normal and only briefly after the 3rd and 4th injection above the upper limit of normal, while peak and trough values increased over the 24-week observation period. Oestradiol and dihydrotestosterone followed this pattern, not exceeding the normal limits. No serious side-effects were noted. Slight increases in body weight, haemoglobin, haematocrit, prostate volume and PSA, suppression of gonadotrophins as well as increased ejaculation frequency occurred as signs of adequate testosterone substitution. CONCLUSION Testosterone undecanoate is well tolerated by the patients. The injection intervals can be extended even beyond the 6-week periods chosen in the present study. Altogether, intramuscular testosterone undecanoate appears to be well suited for long-term substitution therapy in hypogonadism and hormonal male contraception Links to these articles: 1. http://www.eje-online.org/cgi/conten...ract/132/4/514 2. http://www.blackwell-synergy.com/lin...5.1999.00881.x Last edited by miami797; 28-05-2007 at 05:03 PM.