Testosterone can be administered parenterally , but it has more irregular prolonged absorption time and greater activity in muscle in enanthate , undecanoate , or cypionate ester form. These derivatives are hydrolyzed to release free testosterone at the site of injection; absorption rate (and thus injection schedule) varies among different esters, but medical injections are normally done anywhere between semi-weekly to once every 12 weeks. A more frequent schedule may be desirable in order to maintain a more constant level of hormone in the system.  Injectable steroids are typically administered into the muscle, not into the vein, to avoid sudden changes in the amount of the drug in the bloodstream. In addition, because estered testosterone is dissolved in oil, intravenous injection has the potential to cause a dangerous embolism (clot) in the bloodstream.
Kathryn Retzler, ND is a graduate of NCNM. She completed an internship with Andrew Weil, MD at the University of Arizona’s Integrative Medicine Program and a residency with Bruce Dickson, ND in McMinnville, Ore. Dr. Retzler currently is a part-time clinical consultant at ZRT Laboratory, where she provides support to physicians and pharmacists about hormone testing and bioidentical hormone supplementation. She also has a private practice in Portland, with a focus on hormone balance and neurotransmitter optimization, and facilitates groups on healthy detoxification and ideal weight naturally.
10. Cannel, MD, John Jacob, "The Truth About Vitamin D Toxicity," http:///. Published September 4, 2003. Accessed May 24, 2006. 11. Rosenfeld, Louis, "Vitamine - vitamin. The early years of discovery," Clinical Chemistry, Vol. 43 No. 4 (1997) 680-685. 12. DeLuca, Hector F., "Historical Overview," in Feldman et al., eds., Vitamin D, San Diego: Academic Press (1997) 3-11. 13. Dobs, et al., "Effects of pravastatin, a new HMG-CoA reductase inhibitor, on vitamin D synthesis in man," Metabolism, Vol. 40 No. 5 (1991) 524-8. 14. Folkers, et al., "Lovastatin decreases coenzyme Q levels in humans," Proc Natl Acad Sci USA Vol. 87 No. 22 (1990) 8931-4. 15. Heaney, Robert P., "The Vitamin D requirement in health and disease," Journal of Steroid Biochemistry & Molecular Biology, 97 (2005)13-19. 16. Cannel, MD, John Jacob, "The Vitamin D Newsletter: April 2006 -- Dr. Cannell Answers Readers' Questions," Vitamin D Council: http:///PDFs/April2006-. Published April 1, 2006. Accessed May 25, 2006. 17. Masterjohn, Chris, "Vitamin A on Trial: Does Vitamin A Cause Osteoporosis?" Wise Traditions , Spring 2006.