Injectable DMAU for Male Contraception in Healthy Male Volunteers (CCN015)

Healthy Men Clinical Trial

— DMAU  

Official title:

Injectable DMAU for Male Contraception: Safety and Tolerability, Pharmacokinetics and Pharmacodynamics of Single IM or SC DMAU Injection Dose Escalation Study in Healthy Male Volunteers

Clinical Trial Details — Status: Recruiting

Administrative data

• NCT number: NCT02927210
• Other study ID #: CCN015
• Secondary ID: HHSN275201200002
• Status: Recruiting
• Phase: Phase 1
• Start date: December 2016
• Est. completion date: December 2024

Study information

• Verified date: July 2021
• Source: Health Decisions
• Contact: Christina Wang, MD
• Phone: 310-222-2503
• Email: wang[@]labiomed.org
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial Summary

This is a Phase I multicenter, double-blind, single dose, dose-ranging study, in healthy men to evaluate the safety and tolerability, pharmacokinetics and pharmacodynamics of Dimethandrolone Undecanoate (DMAU) administered as an intramuscular or subcutaneous injection.

Description:

This single dose, dose-ranging study will be conducted in two centers: the Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center and the University of Washington.

Single doses of DMAU in castor oil/benzyl benzoate injections intramuscularly (IM) (80 mg, 240 mg, 480 mg, and 800 mg) or administered subcutaneously (SC) (50 mg, 100 mg and 200 mg) were selected for this dose-escalating study. Twelve subjects will complete this study at each of the DMAU doses (10 on DMAU and 2 on placebo injections) yielding a total of 84 completed subjects (70 on DMAU and 14 on placebo) across both sites. Safety will be assessed in all subjects and recovery will be assessed in two subjects receiving lower doses, either IM or SC, before additional men receive higher doses of IM or SC of DMAU. In addition to safety and tolerability, suppression of serum T, E2, gonadotropins, and SHBG will be assessed as secondary pharmacodynamic (PD) endpoints. PK of DMAU and DMA will be assessed through blood draws done at each visit. Suppression of spermatogenesis will be assessed with semen analysis.

DMAU injections will be administered at the study site by research nurses or physicians. For intramuscular injections, the staff will inject DMAU in castor oil into the gluteal region following standard procedures for intramuscular steroid injection. Abdominal subcutaneous injections will follow standard subcutaneous procedures. The subject will be observed for at least 30 minutes before release from the study site.

Recruitment information / eligibility

• Status: Recruiting
• Enrollment: 84
• Est. completion date: December 2024
• Est. primary completion date: December 2024
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: Male
• Age group: 18 Years to 50 Years

Eligibility

Inclusion Criteria:

Men who meet all the following criteria are eligible for enrollment in the trial:

1. Male volunteers in good health as confirmed by physical examination, medical history, and clinical laboratory tests of blood and urine at the time of screening.

2. 18 to 50 years of age (inclusive) at the time of the enrollment visit.

3. BMI = 33 calculated as weight in kg/ (height in m2).

4. Weight =60 kg.

5. No history of hormonal therapy use in the three months prior to the first screening visit.

6. Agree to use a recognized effective method of contraception with any female partner (i.e. at a minimum, barrier plus an additional method of contraception) during the course of the study treatment and recovery phases until recovery is confirmed and study exit occurs.

7. Subjects will refrain from donating blood or plasma during the study period.

8. Subjects will be advised to refrain from excessive alcoholic consumption during the study period. (No more than 15 drinks per week and no alcohol consumption within 24 hours of a study visit.)

9. No known or suspected current alcohol dependence syndrome, chronic marijuana use, or any illicit drug use that may affect metabolism/transformation of steroid hormones and study treatment compliance.

10. In the opinion of the investigator, subject is able to comply with the protocol, understand and sign an informed consent and HIPAA form.

12. Subjects will be advised to refrain from major changes in their level of exercise during the study period.

Exclusion Criteria:

Men who meet any of the following criteria are NOT eligible for enrollment in the trial:

1. Men participating in another clinical trial involving an investigational drug within the 30 days prior to the first screening visit.

2. Men not living in the catchment area of the clinic or within a reasonable distance from the study site.

3. Clinically significant abnormal physical and laboratory findings at screening.

4. Elevated PSA (levels = 2.5 ng/mL) at screening, according to local laboratory normal values.

5. Abnormal serum chemistry values at screening, according to local laboratory reference ranges that indicate liver or kidney dysfunction or that may be considered clinically significant. In addition, the following upper limits will be observed: fasting bilirubin less than 2 mg/dL, cholesterol less than 221 mg/dL, and fasting triglycerides less than 201 mg/dL.

6. Abnormal semen analyses or abnormal semen concentration as defined by the WHO semen manual.

7. Use of androgens within 3 months before first screening visit except for long acting testosterone injections (e.g. Testosterone undecanoate) which will require a wash out period of 6 months prior to screening.

8. Ongoing use of body building substances including nutritional supplements.

9. Systolic BP > 130 mm Hg and Diastolic blood pressure BP > 80 and mm Hg; Blood pressure (BP) will be taken 3 times at 5 - minute intervals and the mean of all measurements be used to determine eligibility).

10. Clinically significant abnormal EKG or a QTc interval of > 450 msec.

11. PHQ-9 score of 15 or above.

12. History of hypertension, including hypertension controlled with treatment.

13. Known history of primary testicular disease or disorders of the hypothalamic-pituitary axis.

14. Benign or malignant liver tumors; active liver disease.

15. History of breast carcinoma.

16. Known history of androgen deficiency due to hypothalamic-pituitary or testicular disease.

17. Known history of cardiovascular, renal, hepatic or prostatic disease or significant psychiatric illness.

18. Positive serology for active Hepatitis (not immunization-related serology) or HIV at screening visit.

19. A serious systemic disease such as diabetes mellitus or obesity (body weight greater than BMI >33 kg/m2 as above).

20. History of known, untreated sleep apnea.

22. Partner is known to be pregnant. 23. Men desiring fertility within the first seven months of study participation.

24. Men participating in competitive sports where drug screening for prohibited substances (including anabolic steroids) is routine. Exclusion is due to the potential of testing positive for androgens that may occur from their study participation coupled with the unknown efficacy (i.e. duration of positive testing) from a single injection.

26. Use of sex steroids or medications which might interfere with steroid metabolism (i.e. ketoconazole, finasteride, oral corticosteroids, dutasteride and statins).

27. Use of medications that will interfere or interact with DMAU.

Related Conditions & MeSH terms

• Healthy Men
• Male Contraception

Intervention

Drug:
• Dimethandrolone Undecanoate
Single doses of DMAU in castor oil/benzyl benzoate injections intramuscularly (IM) (80 mg, 240 mg, 480 mg, and 800 mg) or administered subcutaneously (SC) (50 mg, 100 mg and 200 mg).
• Placebo
Placebo injections that look like the DMAU injections but with no active ingredients

Locations

Country	Name	City	State
United States	University of Washington Medical Center & Health Sciences	Seattle	Washington
United States	Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center	Torrance	California

Sponsors (4)

Lead Sponsor	Collaborator
Health Decisions	Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, University of Washington

Country where clinical trial is conducted

United States, 

References & Publications (33)

Attardi BJ, Engbring JA, Gropp D, Hild SA. Development of dimethandrolone 17beta-undecanoate (DMAU) as an oral male hormonal contraceptive: induction of infertility and recovery of fertility in adult male rabbits. J Androl. 2011 Sep-Oct;32(5):530-40. doi: 10.2164/jandrol.110.011817. Epub 2010 Dec 16. — View Citation

Attardi BJ, Hild SA, Koduri S, Pham T, Pessaint L, Engbring J, Till B, Gropp D, Semon A, Reel JR. The potent synthetic androgens, dimethandrolone (7a,11ß-dimethyl-19-nortestosterone) and 11ß-methyl-19-nortestosterone, do not require 5a-reduction to exert their maximal androgenic effects. J Steroid Biochem Mol Biol. 2010 Oct;122(4):212-8. doi: 10.1016/j.jsbmb.2010.06.009. Epub 2010 Jun 25. — View Citation

Attardi BJ, Hild SA, Reel JR. Dimethandrolone undecanoate: a new potent orally active androgen with progestational activity. Endocrinology. 2006 Jun;147(6):3016-26. Epub 2006 Feb 23. — View Citation

Attardi BJ, Marck BT, Matsumoto AM, Koduri S, Hild SA. Long-term effects of dimethandrolone 17ß-undecanoate and 11ß-methyl-19-nortestosterone 17ß-dodecylcarbonate on body composition, bone mineral density, serum gonadotropins, and androgenic/anabolic activity in castrated male rats. J Androl. 2011 Mar-Apr;32(2):183-92. doi: 10.2164/jandrol.110.010371. Epub 2010 Aug 26. — View Citation

Attardi BJ, Pham TC, Radler LC, Burgenson J, Hild SA, Reel JR. Dimethandrolone (7alpha,11beta-dimethyl-19-nortestosterone) and 11beta-methyl-19-nortestosterone are not converted to aromatic A-ring products in the presence of recombinant human aromatase. J Steroid Biochem Mol Biol. 2008 Jun;110(3-5):214-22. doi: 10.1016/j.jsbmb.2007.11.009. — View Citation

Contraceptive efficacy of testosterone-induced azoospermia in normal men. World Health Organization Task Force on methods for the regulation of male fertility. Lancet. 1990 Oct 20;336(8721):955-9. — View Citation

Cook CE, Kepler JA. 7alpha,11beta-Dimethyl-19-nortestosterone: a potent and selective androgen response modulator with prostate-sparing properties. Bioorg Med Chem Lett. 2005 Feb 15;15(4):1213-6. — View Citation

Cummings DE, Kumar N, Bardin CW, Sundaram K, Bremner WJ. Prostate-sparing effects in primates of the potent androgen 7alpha-methyl-19-nortestosterone: a potential alternative to testosterone for androgen replacement and male contraception. J Clin Endocrinol Metab. 1998 Dec;83(12):4212-9. — View Citation

Frey-Wettstein M, Craddock CG. Testosterone-induced depletion of thymus and marrow lymphocytes as related to lymphopoiesis and hematopoiesis. Blood. 1970 Mar;35(3):257-71. — View Citation

Gu Y, Liang X, Wu W, Liu M, Song S, Cheng L, Bo L, Xiong C, Wang X, Liu X, Peng L, Yao K. Multicenter contraceptive efficacy trial of injectable testosterone undecanoate in Chinese men. J Clin Endocrinol Metab. 2009 Jun;94(6):1910-5. doi: 10.1210/jc.2008-1846. Epub 2009 Mar 17. — View Citation

Gu YQ, Wang XH, Xu D, Peng L, Cheng LF, Huang MK, Huang ZJ, Zhang GY. A multicenter contraceptive efficacy study of injectable testosterone undecanoate in healthy Chinese men. J Clin Endocrinol Metab. 2003 Feb;88(2):562-8. — View Citation

Hild SA, Attardi BJ, Koduri S, Till BA, Reel JR. Effects of synthetic androgens on liver function using the rabbit as a model. J Androl. 2010 Sep-Oct;31(5):472-81. doi: 10.2164/jandrol.109.009365. Epub 2010 Apr 8. — View Citation

Ilani N, Roth MY, Amory JK, Swerdloff RS, Dart C, Page ST, Bremner WJ, Sitruk-Ware R, Kumar N, Blithe DL, Wang C. A new combination of testosterone and nestorone transdermal gels for male hormonal contraception. J Clin Endocrinol Metab. 2012 Oct;97(10):3476-86. doi: 10.1210/jc.2012-1384. Epub 2012 Jul 12. — View Citation

Kaminetsky J, Jaffe JS, Swerdloff RS. Pharmacokinetic Profile of Subcutaneous Testosterone Enanthate Delivered via a Novel, Prefilled Single-Use Autoinjector: A Phase II Study. Sex Med. 2015 Sep 17;3(4):269-79. doi: 10.1002/sm2.80. eCollection 2015 Dec. — View Citation

Keenan CM, Vidal JD. Standard morphologic evaluation of the heart in the laboratory dog and monkey. Toxicol Pathol. 2006;34(1):67-74. — View Citation

Kumar N, Didolkar AK, Monder C, Bardin CW, Sundaram K. The biological activity of 7 alpha-methyl-19-nortestosterone is not amplified in male reproductive tract as is that of testosterone. Endocrinology. 1992 Jun;130(6):3677-83. — View Citation

Kumar N, Suvisaari J, Tsong YY, Aguillaume C, Bardin CW, Lähteenmaki P, Sundaram K. Pharmacokinetics of 7 alpha-methyl-19-nortestosterone in men and cynomolgus monkeys. J Androl. 1997 Jul-Aug;18(4):352-8. — View Citation

Lee KK, Berman N, Alexander GM, Hull L, Swerdloff RS, Wang C. A simple self-report diary for assessing psychosexual function in hypogonadal men. J Androl. 2003 Sep-Oct;24(5):688-98. — View Citation

Malhotra A, Buttrick P, Scheuer J. Effects of sex hormones on development of physiological and pathological cardiac hypertrophy in male and female rats. Am J Physiol. 1990 Sep;259(3 Pt 2):H866-71. — View Citation

Marsh JD, Lehmann MH, Ritchie RH, Gwathmey JK, Green GE, Schiebinger RJ. Androgen receptors mediate hypertrophy in cardiac myocytes. Circulation. 1998 Jul 21;98(3):256-61. — View Citation

Meriggiola MC, Costantino A, Bremner WJ, Morselli-Labate AM. Higher testosterone dose impairs sperm suppression induced by a combined androgen-progestin regimen. J Androl. 2002 Sep-Oct;23(5):684-90. — View Citation

Morgentaler A, Dobs AS, Kaufman JM, Miner MM, Shabsigh R, Swerdloff RS, Wang C. Long acting testosterone undecanoate therapy in men with hypogonadism: results of a pharmacokinetic clinical study. J Urol. 2008 Dec;180(6):2307-13. doi: 10.1016/j.juro.2008.08.126. Epub 2008 Oct 18. — View Citation

Rothman MS, Carlson NE, Xu M, Wang C, Swerdloff R, Lee P, Goh VH, Ridgway EC, Wierman ME. Reexamination of testosterone, dihydrotestosterone, estradiol and estrone levels across the menstrual cycle and in postmenopausal women measured by liquid chromatography-tandem mass spectrometry. Steroids. 2011 Jan;76(1-2):177-82. doi: 10.1016/j.steroids.2010.10.010. Epub 2010 Nov 9. — View Citation

Surampudi P, Page ST, Swerdloff RS, Nya-Ngatchou JJ, Liu PY, Amory JK, Leung A, Hull L, Blithe DL, Woo J, Bremner WJ, Wang C. Single, escalating dose pharmacokinetics, safety and food effects of a new oral androgen dimethandrolone undecanoate in man: a prototype oral male hormonal contraceptive. Andrology. 2014 Jul;2(4):579-587. doi: 10.1111/j.2047-2927.2014.00216.x. Epub 2014 May 2. — View Citation

Swerdloff RS, Wang C, Cunningham G, Dobs A, Iranmanesh A, Matsumoto AM, Snyder PJ, Weber T, Longstreth J, Berman N. Long-term pharmacokinetics of transdermal testosterone gel in hypogonadal men. J Clin Endocrinol Metab. 2000 Dec;85(12):4500-10. — View Citation

Vermeulen A, Verdonck L, Kaufman JM. A critical evaluation of simple methods for the estimation of free testosterone in serum. J Clin Endocrinol Metab. 1999 Oct;84(10):3666-72. — View Citation

von Eckardstein S, Noe G, Brache V, Nieschlag E, Croxatto H, Alvarez F, Moo-Young A, Sivin I, Kumar N, Small M, Sundaram K; International Committee for Contraception Research, The Population Council. A clinical trial of 7 alpha-methyl-19-nortestosterone implants for possible use as a long-acting contraceptive for men. J Clin Endocrinol Metab. 2003 Nov;88(11):5232-9. — View Citation

Wang C, Catlin DH, Demers LM, Starcevic B, Swerdloff RS. Measurement of total serum testosterone in adult men: comparison of current laboratory methods versus liquid chromatography-tandem mass spectrometry. J Clin Endocrinol Metab. 2004 Feb;89(2):534-43. — View Citation

Wang C, Harnett M, Dobs AS, Swerdloff RS. Pharmacokinetics and safety of long-acting testosterone undecanoate injections in hypogonadal men: an 84-week phase III clinical trial. J Androl. 2010 Sep-Oct;31(5):457-65. doi: 10.2164/jandrol.109.009597. Epub 2010 Feb 4. — View Citation

Wang C, Shiraishi S, Leung A, Baravarian S, Hull L, Goh V, Lee PW, Swerdloff RS. Validation of a testosterone and dihydrotestosterone liquid chromatography tandem mass spectrometry assay: Interference and comparison with established methods. Steroids. 2008 Dec 12;73(13):1345-52. doi: 10.1016/j.steroids.2008.05.004. Epub 2008 May 21. Erratum in: Steroids. 2018 Jul;135:108. — View Citation

Wang C, Swerdloff R, Kipnes M, Matsumoto AM, Dobs AS, Cunningham G, Katznelson L, Weber TJ, Friedman TC, Snyder P, Levine HL. New testosterone buccal system (Striant) delivers physiological testosterone levels: pharmacokinetics study in hypogonadal men. J Clin Endocrinol Metab. 2004 Aug;89(8):3821-9. — View Citation

Weinbauer GF, Göckeler E, Nieschlag E. Testosterone prevents complete suppression of spermatogenesis in the gonadotropin-releasing hormone antagonist-treated nonhuman primate (Macaca fascicularis). J Clin Endocrinol Metab. 1988 Aug;67(2):284-90. — View Citation

World Health Organization Task Force on Methods for the Regulation of Male Fertility. Contraceptive efficacy of testosterone-induced azoospermia and oligozoospermia in normal men. Fertil Steril. 1996 Apr;65(4):821-9. Erratum in: Fertil Steril 1996 Jun;65(6):1267. — View Citation

* Note: There are 33 references in all — Click here to view all references

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Incidence of treatment emergent adverse events (safety and tolerability) with a single IM or SC injection of escalating doses of Dimethandrolone Undecanoate (DMAU)		5-7 months
Primary	Changes from baseline in sexual function (safety and tolerability) with a single IM or SC injection of escalating doses of Dimethandrolone Undecanoate (DMAU) using the psychosexual daily questionnaire		5-7 months
Primary	Changes from baseline in mood (safety and tolerability) with a single IM or SC injection of escalating doses of Dimethandrolone Undecanoate (DMAU) using the Patient Health Questionnaire-9		5-7 months
Primary	Changes from baseline in sodium (safety and tolerability) with a single IM or SC injection of escalating doses of Dimethandrolone Undecanoate (DMAU)		5-7 months
Primary	Changes from baseline in potassium (safety and tolerability) with a single IM or SC injection of escalating doses of Dimethandrolone Undecanoate (DMAU)		5-7 months
Primary	Changes from baseline in chloride (safety and tolerability) with a single IM or SC injection of escalating doses of Dimethandrolone Undecanoate (DMAU)		5-7 months
Primary	Changes from baseline in bicarbonate (safety and tolerability) with a single IM or SC injection of escalating doses of Dimethandrolone Undecanoate (DMAU)		5-7 months
Primary	Changes from baseline in fasting glucose (safety and tolerability) with a single IM or SC injection of escalating doses of Dimethandrolone Undecanoate (DMAU)		5-7 months
Primary	Changes from baseline in blood urea nitrogen (safety and tolerability) with a single IM or SC injection of escalating doses of Dimethandrolone Undecanoate (DMAU)		5-7 months
Primary	Changes from baseline in creatinine (safety and tolerability) with a single IM or SC injection of escalating doses of Dimethandrolone Undecanoate (DMAU)		5-7 months
Primary	Changes from baseline in calcium (safety and tolerability) with a single IM or SC injection of escalating doses of Dimethandrolone Undecanoate (DMAU)		5-7 months
Primary	Changes from baseline in total bilirubin (safety and tolerability) with a single IM or SC injection of escalating doses of Dimethandrolone Undecanoate (DMAU)		5-7 months
Primary	Changes from baseline in alkaline phosphatase (safety and tolerability) with a single IM or SC injection of escalating doses of Dimethandrolone Undecanoate (DMAU)		5-7 months
Primary	Changes from baseline in alanine aminotransferase (safety and tolerability) with a single IM or SC injection of escalating doses of Dimethandrolone Undecanoate (DMAU)		5-7 months
Primary	Changes from baseline in aspartate transaminase (safety and tolerability) with a single IM or SC injection of escalating doses of Dimethandrolone Undecanoate (DMAU)		5-7 months
Primary	Changes from baseline in albumin (safety and tolerability) with a single IM or SC injection of escalating doses of Dimethandrolone Undecanoate (DMAU)		5-7 months
Primary	Changes from baseline in blood pressure (safety and tolerability) with a single IM or SC injection of escalating doses of Dimethandrolone Undecanoate (DMAU)		5-7 months
Primary	Changes from baseline in pulse (safety and tolerability) with a single IM or SC injection of escalating doses of Dimethandrolone Undecanoate (DMAU)		5-7 months
Primary	Changes from baseline in respiratory rate (safety and tolerability) with a single IM or SC injection of escalating doses of Dimethandrolone Undecanoate (DMAU)		5-7 months
Primary	Changes from baseline in body mass index (safety and tolerability) with a single IM or SC injection of escalating doses of Dimethandrolone Undecanoate (DMAU)		5-7 months
Secondary	Pharmacokinetics of DMAU and DMA using AUC (0-t, where t is the last time-point with measurable concentration)		5-7 months
Secondary	Pharmacodynamics of DMAU by assessing the suppression of serum Testosterone (T) using mean values at each visit		5-7 months
Secondary	Pharmacodynamics of DMAU by assessing the suppression of Dihydrotestosterone (DHT) using mean values at each visit		5-7 months
Secondary	Pharmacodynamics of DMAU by assessing the suppression of Estradiol (E2) using mean values at each visit		5-7 months
Secondary	Pharmacodynamics of DMAU by assessing the suppression of Follicle Stimulating Hormone (FSH) using mean values at each visit		5-7 months
Secondary	Pharmacodynamics of DMAU by assessing the suppression of Luteinizing Hormone (LH) using mean values at each visit		5-7 months
Secondary	Pharmacodynamics of DMAU by assessing the suppression of Sex Hormone Binding Globulin (SHBG) using mean values at each visit		5-7 months
Secondary	Pharmacodynamics of DMAU by assessing the suppression of serum T using number of subjects with FSH and LH = 1.0 IU/L		5-7 months
Secondary	Pharmacodynamics of DMAU by assessing the suppression of serum T using percentage of subjects with FSH and LH = 1.0 IU/L		5-7 months
Secondary	Pharmacodynamics of DMAU by assessing the suppression of DHT using number of subjects with FSH and LH = 1.0 IU/L		5-7 months
Secondary	Pharmacodynamics of DMAU by assessing the suppression of DHT using percentage of subjects with FSH and LH = 1.0 IU/L		5-7 months
Secondary	Pharmacodynamics of DMAU by assessing the suppression of E2 using number of subjects with FSH and LH = 1.0 IU/L		5-7 months
Secondary	Pharmacodynamics of DMAU by assessing the suppression of E2 using percentage of subjects with FSH and LH = 1.0 IU/L		5-7 months
Secondary	Pharmacodynamics of DMAU by assessing the suppression of FSH using number of subjects with FSH and LH = 1.0 IU/L		5-7 months
Secondary	Pharmacodynamics of DMAU by assessing the suppression of FSH using of subjects with FSH and LH = 1.0 IU/L		5-7 months
Secondary	Pharmacodynamics of DMAU by assessing the suppression of LH using number of subjects with FSH and LH = 1.0 IU/L		5-7 months
Secondary	Pharmacodynamics of DMAU by assessing the suppression of LH using percentage of subjects with FSH and LH = 1.0 IU/L		5-7 months
Secondary	Pharmacodynamics of DMAU by assessing the suppression of SHBG using number of subjects with FSH and LH = 1.0 IU/L		5-7 months
Secondary	Pharmacodynamics of DMAU by assessing the suppression of SHBG using percentage of subjects with FSH and LH = 1.0 IU/L		5-7 months
Secondary	Suppression of spermatogenesis as assessed by semen analyses using number of subjects with sperm concentration <1 million (M)/mL		5-7 months
Secondary	Suppression of spermatogenesis as assessed by semen analyses using percentage of subjects with sperm concentration <1 million (M)/mL		5-7 months