Possibly Everything You Might Wanto to Know about Testosterone I

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Testosterone
by Medscape

Monograph - Testosterone, Testosterone cypionate, Testosterone enanthate, Testosterone propionate
Class: ANDROGENS(68:08)

Sections: Introduction | Uses | Dosage and Administration | Cautions | Drug Interactions | Laboratory test Interferences | Pharmacology | Pharmacokinetics | Chemistry and Stability | Preparations

Introduction

Testosterone, the principal endogenous androgen, is a naturally occurring androgenic anabolic steroid hormone.
Uses

Testosterone is used mainly for replacement or substitution of diminished or absent endogenous testicular hormone.

•Uses in Males

Hypogonadism

In males, testosterone is used for the management of congenital or acquired primary hypogonadism such as that resulting from orchidectomy or from testicular failure caused by cryptorchidism, bilateral torsion, orchitis, or vanishing testis syndrome. Testosterone also is used in males for the management of congenital or acquired hypogonadotropic hypogonadism such as that resulting from idiopathic gonadotropin or gonadotropin-releasing hormone (luteinizing hormone releasing hormone) deficiency or from pituitary-hypothalamic injury caused by tumors, trauma, or radiation. If any of these conditions occur before puberty, androgen replacement therapy will be necessary during adolescence for the development of secondary sexual characteristics and prolonged therapy will be required to maintain these characteristics. Prolonged androgen therapy also is required to maintain sexual characteristics in other males who develop testosterone deficiency after puberty.

Manifestations.

Hypogonadism in males may manifest with signs and symptoms of testosterone deficiency and/or infertility, with manifestations depending principally on the age of the patient at the time of development. Hypogonadism seldom is recognized before the age of puberty unless it is associated with growth retardation or other anatomic and/or endocrine abnormalities. When hypogonadism develops before puberty onset, manifestations include small testes, phallus, and prostate; minimal pubic and axillary hair; disproportionately long arms and legs (secondary to delayed epiphyseal closure); reduced male musculature; gynecomastia; and a persistently high-pitched voice. Postpubertal loss of testicular function results in slowly evolving subtle clinical manifestations, which may be difficult to appreciate in aging men because they often are attributed to growing old. Growth of body hair usually slows, while the voice and size of the phallus and prostate remain unchanged. Patients with postpubertal hypogonadism may manifest a progressive decrease in muscle mass, libido loss, impotence, oligospermia or azoospermia, and/or occasionally menopause-type hot flushes (with acute onset of hypogonadism). Hypogonadism also is associated with a risk of osteoporosis and resultant fractures. Many cases of postpubertal hypogonadism are initially detected during fertility evaluations.

Hypogonadism Associated with HIV Infection.

Hypogonadism occurs commonly in human immunodeficiency virus (HIV)-infected men, particularly as their disease progresses to acquired immunodeficiency syndrome (AIDS). Hypogonadism has been reported in up to 50% of HIV-infected men, being most likely in those with AIDS; however, the incidence may now be lower as a result of highly active antiretroviral therapy (HAART) and resultant improved overall health in HIV-infected patients. Such patients generally exhibit low serum testosterone concentrations and usually low (indicating hypothalamic-pituitary involvement) or occasionally high (indicating testicular involvement) gonadotropin concentrations. In addition to typical manifestations of hypogonadism (e.g., impaired sexual mood and functioning, loss of body hair, gynecomastia, bone loss, impaired sense of well-being), hypogonadal HIV-infected men may exhibit a disproportionate loss of lean body mass and muscle wasting. The etiology of hypotestosteronism in HIV-infected men likely is multifactorial and may show interindividual variation and may include primary testicular problems, changes in the hypothalamic-pitutitary-gonadal axis, and/or changes caused by chronic illness, poor nutrition, or medications; approximately 25% of hypogonadism cases in HIV-infected men are primary. Testosterone replacement therapy is considered the androgen of choice for the treatment of androgen deficiency (e.g., hypogonadism) and AIDS wasting in HIV-infected men.

Male Climacteric.

The concept of male climacteric (andropause) remains controversial. However, growing evidence indicates that some aging men develop reduced testosterone production and associated manifestations of hypogonadism such as decreased libido, impotence, decreased body hair growth, decreased muscle mass, increased risk of cardiovascular disease, and decreased bone mass and resultant osteoporosis. Measurements of free testosterone and/or sex hormone binding globulin (SHBG) concentrations usually are necessary to demonstrate the abnormality.

There currently is a paucity of information from well-designed study on the use of testosterone in middle-aged or older men who do not meet the clinical diagnostic criteria for established hypogonadism but who may have testosterone levels in the low range for young adults and/or who show one or more manifestation common to both aging and hypogonadism. In addition, studies that have been conducted generally have been of short duration, involved small numbers of patients, and often lacked adequate controls. Therefore, assessments of risks and benefits have been limited to date, and uncertainties remain about the value of testosterone therapy in older men without a clinical diagnosis of hypogonadism. In most studies to date, it appears that older men were given testosterone dosages that increased testosterone levels to the normal physiologic range for young adult males. Because of the potential risks of testosterone therapy and the availability of other safe and effective intervention options for some of the diseases and conditions it is intended to prevent or treat (e.g., biphosphonates for osteoporosis), testosterone should be considered a therapeutic rather than a preventative measure in aging men. Although endogenous testosterone levels clearly decline with aging, it currently is unclear whether such decreased levels affect health outcomes in older men. Much remains unknown about how physiologic pathways are affected by changes in endogenous testosterone concentrations or by the administration of exogenous testosterone in aging men.

Current limited evidence suggests that testosterone therapy in aging men may produce beneficial effects on body composition, strength, bone density, frailty, cognitive function, mood, sexual function, and quality of life. However, additional evidence from well-designed studies is needed to further elucidate the role of testosterone therapy in aging men. Well-designed studies also are needed to quantify the risks of testosterone therapy on symptomatic prostatic hyperplasia (BPH) and prostate cancer, which are of major concern. The Institute of Medicine (IOM) of the National Academies recognizes that clinical evidence to date suggests some benefit and possible risk of testosterone therapy in older men, but they state that additional placebo-controlled studies are needed to determine the nature and extent of therapeutic benefits in this age group.

Testosterone Replacement Therapy for Hypogonadism.

Men with symptomatic hypogonadism and clearly low testosterone concentrations (free or total, considering SHBG) are potential candidates for testosterone replacement therapy; however, the potential prostatic risk must be considered. Serum total (bound and free) testosterone concentrations less than 300 ng/dL generally are considered indicative of hypogonadism in men, and the biochemical goal of hormone replacement therapy with testosterone generally is to increase serum total testosterone concentrations to within the normal physiologic range of 300–1200 ng/mL. The principal goals of testosterone replacement are to restore sexual function, libido, well-being, and behavior; to stimulate and maintain virilization (e.g., secondary sex characteristics such as muscle mass, body hair, phallus growth); to optimize bone density and prevent osteoporosis; to possibly normalize somatotropin (growth hormone) concentrations in geriatric men; to potentially improve cardiovascular risk; and to restore fertility in cases of hypogonadotropic hypogonadism. In HIV-infected men, additional goals include improvement in mood (e.g,, depression), energy level (fatigue), quality of life, and lean body mass (wasting syndrome); however, clinical response to testosterone therapy in HIV-infected men is not necessarily correlated to baseline serum testosterone concentrations, and eugonadal HIV-infected men may benefit from such therapy.

Delayed Puberty

When the diagnosis is well established, testosterone may be used to stimulate puberty in carefully selected males with delayed puberty. These males usually have a family history of delayed puberty that is not caused by a pathologic disorder. Brief treatment with conservative doses of an androgen may occasionally be justified in these males if they do not respond to psychologic support. Because androgens may adversely affect bone maturation in these prepubertal males, this potential risk should be fully discussed with the patient and his parents prior to initiation of androgen therapy. (See Cautions: Pediatric Precautions.) If androgen therapy is initiated in these prepubertal males, radiographs of the hand and wrist should be obtained at 6-month intervals to determine the effect of therapy on the epiphyseal centers. Testosterone is designated an orphan drug by the US Food and Drug Administration (FDA) for use in this condition.

Corticosteroid-induced Hypogonadism and Osteoporosis

Patients receiving long-term corticosteroid therapy may develop hypogonadism secondary to inhibition of secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the pituitary as well as secondary to direct effects on the testes and ovaries, and such hypogonadism may be associated with bone loss. Therefore, all patients receiving prolonged corticosteroid therapy should be assessed for possible hypogonadism, which should be corrected if present. Unlike experience with hormone replacement therapy (HRT, combined estrogen and progestin therapy) in postmenopausal women receiving chronic prednisone therapy, there currently is only limited information on the effect of androgen (e.g., testosterone) replacement therapy in men with hypogonadism secondary to long-term conticosteroid therapy. In a small study in men with corticosteroid-treated asthma and low serum testosterone concentrations, lumbar spine bone mass density (BMD) was increased nearly 4% after 12 months of monthly testosterone injections; lean body mass also was increased and fat mass was reduced. Therefore, men who develop low serum testosterone concentrations while receiving long-term corticosteroid therapy should be offered testosterone replacement therapy in an attempt to treat hypogonadism and possibly reduce the risk of corticosteroid-induced osteoporosis† when contraindications to androgen therapy are not present. Some experts (e.g., the American College of Rheumatology) recommend that such men with serum testosterone concentrations below the physiologic range (i.e., less than 300 ng/mL) receive replacement therapy. The goal of testosterone replacement therapy in men receiving long-term corticosteroid therapy is to provide serum testosterone concentrations within the therapeutic range. It is important that the possibility of prostate cancer be ruled out in any man being considered for such replacement therapy. For additional information on the management of corticosteroid-induced osteoporosis, see Cautions: Musculoskeletal Effects in the Corticosteroids General Statement 68:04.

•Uses in Females

Inopererable Carcinoma of the Breast

In females, testosterone has been used for the palliative treatment of androgen-responsive, advanced, inoperable, metastatic (skeletal) carcinoma of the breast in women who are 1–5 years postmenopausal. Short-acting androgen preparations are preferred when these drugs are indicated for the treatment of carcinoma of the breast, particularly during the early stages of androgen therapy, since androgens occasionally appear to accelerate the disease. The use of a long-acting preparation may preclude attempts to arrest or reverse untoward effects of the drug on tumor progression, hypercalcemia, and/or sodium and water retention. Primary goals of therapy in these women include ablation of the ovaries. Other methods of counteracting estrogen activity include adrenalectomy, hypophysectomy, and/or antiestrogen therapy (e.g., tamoxifen). Androgen therapy also has been used in premenopausal women with carcinoma of the breast who have benefited from oophorectomy and are considered to have a hormone-responsive tumor. The decision to use androgen therapy in women with carcinoma of the breast should be made by an oncologist with expertise in the treatment of this carcinoma.

Postpartum Breast Pain and Engorgement

Testosterone formerly was used for the prevention of postpartum breast pain and engorgement†; however, the drug does not appear to prevent or suppress lactation. Testosterone esters also have been used in combination with estrogens for the prevention of postpartum breast pain and engorgement; however, the US Food and Drug Administration (FDA) has withdrawn approval of estrogen-containing drugs for this indication. Data from controlled studies indicate that the incidence of substantial painful engorgement is low in untreated women, and the condition usually responds to analgesic or other supportive therapy.

Menopause

In females, testosterone esters also are used in combination with estrogens for the management of moderate to severe vasomotor symptoms associated with menopause in patients who do not respond adequately to estrogens alone. While estrogen/androgen combinations were found to be effective for the management of vasomotor symptoms associated with menopause under a determination made by the US Food and Drug Administration (FDA) in 1976, formal administrative proceedings were initiated by the FDA in April 2003 to examine the effectiveness of estrogen/androgen combinations for this indication. FDA is undertaking this action because the agency does not believe there is substantial evidence available to establish the contribution of androgens to the effectiveness of estrogen/androgen combinations for the management of vasomotor symptoms in menopausal women who do not respond to estrogens alone. The FDA will allow continued marketing of combination estrogen/androgen products while the matter is under study.

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•Misuse and Abuse

Because of their anabolic and androgenic effects on performance (ergogenic potential) and physique, androgens have been misused and abused by athletes, bodybuilders, weight lifters, and others, including high school- and college-aged individuals engaged in sports. The drugs also have been misused and abused for cosmetic purposes by noncompetitors attempting to achieve bodies with lean muscle mass. Although historically the drugs have been regarded as ineffective for anabolic and androgenic uses in athletes, recent limited evidence suggests that androgens may increase skeletal muscle mass and strength when used in conjunction with proper (e.g., high-protein, high calorie) diet and training but that their use is not associated with increased power or capacity for aerobic work. There continues to be a lack of evidence of long-term beneficial effects, and the drugs may be associated with substantial adverse health effects and toxicity. When used to improve athletic performance and physique, dosages employed often substantially (e.g., 10- to 1000-fold) exceed usual therapeutic dosages of the drugs. In addition, several androgens often are taken concomitantly (‘‘stacking’’) for extended periods. The extent of misuse and abuse of androgens has not been fully determined, but nonmedical use is believed to be widespread. Estimates for the rate of misuse and abuse by weight lifters and body builders have ranged up to 50–80%. However, in terms of actual numbers, it has been suggested that most misuse and abuse of androgens are by individuals who never compete in sports. Evidence from one study indicates that about 7% of male high school seniors use or have used the drugs. Although the likelihood of use was increased in males intending to participate in school-sponsored sports (particularly football and wrestling), 35% of users had no intention of participating in school-sponsored sports. About 40% of these high school students admitted initiating use of the drugs at 15 years of age or younger. In studies of college students, androgen use among athletes ranged up to about 20%.

Systematic studies to determine the risks of misuse and abuse of androgens have not been performed to date, but evidence from experience with legitimate medical use of the drugs and from case reports in athletes indicates that potential adverse effects in either gender include increased aggression and antisocial behavior (‘‘roid rage’’); psychotic manifestations and affective disorders (e.g., manic episode, depression); changes in libido; adverse alterations in lipoprotein profiles and increased risk of cardiovascular disease (e.g., coronary artery disease, stroke, atherosclerosis); hepatotoxicity (e.g., abnormal liver function test results, liver tumors [hepatic adenomas, hepatocellular carcinoma], peliosis hepatis, jaundice); premature bone maturation and epiphyseal closure with resultant irreversible short stature when initiated in adolescents or younger children; possible increased risk of ruptured tendons and ligaments and of tendonitis; and acne. Other potential adverse effects of androgens in males include gynecomastia, hair loss, testicular atrophy and sperm abnormalities (oligospermia, decreased motility, abnormal morphology, azoospermia), impotence, and prostatic enlargement with resultant difficulty in urinating. Other potential adverse effects in females include clitoral enlargement (which may be irreversible), menstrual irregularities, hirsutism, androgenetic alopecia, deepened voice, and breast atrophy.

Because of the potential for serious adverse effects associated with misuse and abuse of androgens, preventive measures have been initiated, including educational programs, interdiction of black market supplies, drug screening of athletes with associated penalties for use, and other control measures. The prescription, dispensing, distribution, and use of most androgens currently are restricted as controlled substances. In addition, medical and sports experts, including the American College of Sports Medicine, American Medical Association, American Academy of Pediatrics, American College Health Association, National Strength and Conditioning Association, National Collegiate Athletic Association, National Football League, US Olympic Committee, and the International Olympic Committee, consider the use of androgens to enhance athletic performance or physique inappropriate and unacceptable because of known adverse effects, lack of data regarding long-term gains in size and strength, and potential long-term adverse sequelae and because their use by athletes is contrary to the rules and ethical principles of athletic competition.

Dosage and Administration

•Administration

Testosterone is administered by deep IM injection; implants (testosterone pellets) are administered by subcutaneous implantation; testosterone transdermal systems are administered percutaneously by topical application to the skin (Androderm®, Testoderm® TTS) or scrotum (Testoderm®, Testoderm® with Adhesive); and testosterone gel is applied topically to the skin.

IM Injection and Subcutaneous Implantation

Testosterone cypionate, testosterone enanthate, and testosterone propionate are administered by deep IM injection.
IM injection of testosterone and its esters should be made deep into the upper outer quadrant of the gluteus maximus.

If complications associated with subcutaneous testosterone implantation occur, the pellets should be removed; pellets occasionally may slough out, usually secondary to superficial implantation or lack of aseptic precautions.

Transdermal Administration

Patients receiving transdermal testosterone therapy should be carefully instructed in the proper use and disposal of the transdermal system. To obtain optimum results, patients should be given a copy of the patient instructions provided by the manufacturer. To expose the drug-containing film of Testoderm® or the adhesive surface of Testoderm® with Adhesive, Testoderm® TTS, or Androderm®, the protective liner should be peeled and discarded prior to administration.

For nonscrotal application, the transdermal system should then be applied topically to a clean, dry area of skin on the arm, back, or upper buttock for Testoderm® TTS or on the back, abdomen, upper arms, or thigh for Androderm® by firmly pressing the system with the adhesive side touching the skin; these systems should not be applied to the scrotum. If scrotal application is preferred, the transdermal system of Testoderm® or Testoderm® with Adhesive should then be applied topically to clean, dry, scrotal skin; these systems are intended for scrotal application only. The scrotum should be dry-shaved for optimum skin contact; chemical depilatories should not be used. The nonscrotal or scrotal system should be applied immediately after removal from its protective pouch and removal of the protective liner. The system should be pressed firmly in place with the palm of the hand for about 10 seconds, ensuring good contact, particularly around the edges. The application site should not be oily, damaged, or irritated. Application of Androderm® or Testoderm® TTS nonscrotal transdermal systems over bony prominences or on a part of the body that may be subject to prolonged pressure during sleep or sitting (e.g., the deltoid region of the upper arm, the greater trochanter of the femur, the ischial tuberosity) should be avoided since burn-like blisters may occur. If the system should inadvertently come off during the period of use, it may be reapplied or, if necessary, a new system may be applied; in either case, the application schedule employed should be continued.

To minimize and/or prevent potential skin irritation, each testosterone transdermal system should be applied at a different site, with an interval of at least 1 week allowed between applications to a particular site. The manufacturer of Androderm® states that mild skin irritation may be ameliorated with topical hydrocortisone cream 0.5 or 1% after system removal; alternatively, a small amount of triamcinolone acetonide cream 0.1% may be applied to the skin under the drug reservoir to minimize irritation (ointment formulations should not be used because they may reduce testosterone absorption).

Testosterone transdermal systems are applied once daily; to produce serum testosterone concentrations that mimic endogenous profiles, the manufacturer states that Androderm® should be applied at night while the manufacture states that any of the Testoderm® preparations should be administered at about the same time each day preferably in the morning. Transdermal systems applied to the scrotum should be left in place for 22–24 hours and systems applied to other topical sites should be left in place for approximately 24 hours; after this period, the system should be removed and discarded and a new system applied.

The manufacturer of Androderm® states that the transdermal system does not need to be removed during sexual intercourse nor while showering or bathing. Androderm® and Testoderm® TTS have an occlusive backing that prevents sex partners from coming in contact with the active material in the system. Although transfer of the transdermal system itself from the patient’s body to that of their partner is unlikely, if such inadvertent transfer does occur, the transdermal system should be removed immediately and the contacted skin washed. Female partners of patients treated with the transdermal systems should contact a clinician if they notice changes in body hair distribution, significant increases in acne, or other manifestations of virilization.

Topical Administration

Testosterone topical gel should be applied topically once daily, preferably in the morning, to clean, dry, intact skin on the shoulders and upper arms and/or abdomen. The gel should not be applied to the scrotum. Upon opening the unit-dose packet or tube, the entire contents should be squeezed into the palm of the hand and immediately applied to the application site, which should then be allowed to dry for few minutes before dressing; after the gel has dried, the application site should be covered with clothing (e.g., a shirt) in order to prevent transfer to another individual. Hands should be washed with soap and water after application of the gel. It currently is not known how long showering or swimming should be delayed following application of testosterone gel. Pending further accumulation of data, the manufacturer of AndroGel® states that a reasonable approach to optimize testosterone absorption would be to wait at least 5–6 hours after application before showering or swimming. However, showering or swimming after the elapse of just 1 hour should have a minimal effect on the amount of testosterone gel absorbed if done very infrequently. The manufacturer of Testim® recommends that at least 2 hours should elapse between application of the gel and washing of the site.
If unwashed or unclothed skin at the site of testosterone gel application comes in contact with the skin of another individual, the general area of contact should be washed with soap and water as soon as possible.

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•Dosage

Dosage of testosterone is variable and should be individualized according to the condition being treated; the severity of symptoms; the patient’s age, gender, and history of prior androgenic therapy; and the specific testosterone preparation being used. Since regulation of dosage is much less flexible with testosterone implants (pellets) for subcutaneous implantation than with oral, transdermal, topical, or parenteral administration, the estimated amount of testosterone needed should be calculated with great caution.

Various dosage regimens have been used to induce pubertal changes in hypogonadal males. Some clinicians recommend that lower dosages be used initially, followed by gradual increases in dosage as puberty progresses; subsequently, the dosage may be decreased to maintenance levels. Other clinicians state that higher dosages are required initially to induce pubertal changes and lower dosages can then be used for maintenance therapy after puberty. The chronologic and skeletal ages of the patient must be considered when determining the initial dosage and subsequent dosage adjustment. In general, short-term administration (e.g., 4–6 months) of testosterone or testosterone esters and dosages in the lower end of the usual range for replacement are used for the treatment of delayed puberty in males.

IM Dosage

Male Hypogonadism.

For replacement of endogenous testicular hormone in androgen-deficient males, the usual IM dosage is 10–25 mg of testosterone or testosterone propionate 2 or 3 times weekly, 50–400 mg of testosterone cypionate every 2–4 weeks, or 50–400 mg of testosterone enanthate every 2–4 weeks. In general, testosterone therapy is initiated with full therapeutic doses; subsequent dosage adjustment should be made according to the patient’s tolerance and therapeutic response.

Alternatively, some clinicians state that complete androgen replacement in hypogonadal men generally can be achieved with 75–150 mg of testosterone cypionate or enanthateadministered IM every 7–10 days. This regimen generally will achieve relatively physiologic testosterone concentrations throughout the time interval between doses. Longer time intervals between IM doses are more convenient but are associated with greater fluctuations in testosterone concentrations. Higher dosages produce longer-term effects but higher peak concentrations and wider swings between peak and nadir testosterone concentrations and resultant symptom fluctuation in many patients. If less frequent injection is desired, 100–200 mg IM every 2 weeks may be considered. While 300 mg IM every 3 weeks also may be considered for convenience, such dosing is associated with wider testosterone fluctuations and generally is inadequate to ensure a consistent clinical response. For men who develop pronounced symptoms in the week prior to the next dose with such prolonged dosing intervals, a smaller dose at a shorter dosing interval should be tried; in general, serum total testosterone concentrations should exceed 250–300 ng/dL just before the next dose.

If full androgen replacement is not required, lower testosterone dosages are used. For example, in adult males with prepubertal onset of hypogonadism who are going through puberty for the first time with testosterone replacement, testosteronecypionate or enanthate may be initiated at 50–100 mg every 3–4 weeks, gradually increasing the dose in subsequent months as tolerated up to full replacement within 1 year.

Attainment of full virilization in men with hypogonadism may require up to 3–4 years of IM testosterone replacement. Patients generally should be monitored at 4–6 months to assess clinical progress, review compliance, and determine whether any complications or psychologic adjustment problems are present.

For the management of postpubertal cryptorchidism in patients with evidence of hypogonadism, the usual IM dosage is 10–25 mg of testosterone or testosteronepropionate 2 or 3 times weekly.

Inoperable Carcinoma of the Breast

For the palliative treatment of advanced, inoperable, metastatic carcinoma of the breast in women, the use of short-acting androgen preparations rather than those with prolonged activity is preferred, especially during the early stages of treatment, since use of a long-acting preparation may preclude attempts to arrest or reverse untoward effects of the drug on tumor progression, hypercalcemia, and/or sodium and water retention. An IM dosage of 100 mg of testosterone or 50–100 mg of testosteronepropionate, has been given 3 times weekly. Alternatively, 200–400 mg of testosteronecypionate or testosterone enanthate has been given IM every 2–4 weeks.

Subcutaneous Implantation Dosage

For replacement of endogenous testicular hormone in androgen-deficient males (male hypogonadism), the usual dosage of testosterone implants (pellets) is 150–450 mg (two to six 75-mg pellets) implanted subcutaneously every 3–6 months.

For patients being transferred from IM testosterone propionate, the number of testosterone pellets to be implanted subcutaneously depends on the minimum daily requirement of testosterone propionate determined by a gradual reduction in the amount administered parenterally. The usual ratio is 150 mg (two 75-mg pellets) for each 25 mg of IM testosterone propionate required weekly. Thus, patients requiring 75 mg of IM testosterone propionate weekly will usually require 450 mg of testosterone (six 75-mg pellets) implanted subcutaneously. For patients requiring weekly IM injections of 50 mg, subcutaneous implantation of 300 mg (four 75-mg pellets) may be sufficient for approximately 3 months. Correspondingly lower subcutaneous implant dosages should be used in patients requiring lower IM dosages. Approximately one-third of an implanted dose is absorbed systemically during the first month, one-fourth during the second month, and one-sixth during the third month. Adequate effect usually persists for 3–4 months after subcutaneous implantation of the pellets, and occasionally for up to 6 months.

Transdermal Dosage

Transdermal testosterone is commercially available for nonscrotal topical application as a transdermal system delivering 2.5 mg/24 hours (Androderm®) or 5 mg/24 hours (Androderm®, Testoderm® TTS). Transdermal testosterone is commercially available for scrotal topical application as a transdermal system (Testoderm® with or without Adhesive) delivering 4 or 6 mg/24 hours. Dosage should be adjusted according to determinations of serum testosterone concentrations. Because of the variability in analytical values among diagnostic laboratories, all laboratory work for adjusting dosage and assessing the effects of transdermal testosterone should be done at the same laboratory so results can be compared. Patients who have not achieved desired results after 6–8 weeks of transdermal testosterone therapy should be considered for alternative forms of testosterone replacement therapy.
When Androderm® is used for nonscrotal application in the treatment of male hypogonadism, the usual initial transdermal dosage is 5 mg once daily administered nightly as one system delivering 5 mg/24 hours or as two systems delivering 2.5 mg/24 hours. Dosage should be adjusted according to morning serum testosterone concentrations. Depending on requirements, dosage can be increased to 7.5 mg once daily administered nightly as one system delivering 5 mg/24 hours plus one delivering 2.5 mg/24 hours or as three systems delivering 2.5 mg/24 hours or can be decreased to 2.5 mg once daily administered nighly as one system delivering 2.5 mg/24 hours.

When Testostoderm® TTS is used for nonscrotal application in the treatment of male hypogonadism, the usual initial transdermal dosage is 5 mg once daily administered at about the same time each day (preferably in the morning) as one system delivering 5 mg/24 hours. After 3–4 weeks of daily system application, dosage should be adjusted according to serum testosterone concentrations obtained 2–4 hours after application of a transdermal system. Dosage can be increased if necessary to 10 mg once daily administered as two systems delivering 5 mg/24 hours.

When Testostoderm® with or without Adhesive is used for scrotal application in the treatment of male hypogonadism, the usual initial transdermal dosage is 6 mg once daily administered at about the same time each day (preferably in the morning) as one system delivering 6 mg/24 hours. Alternatively when the scrotum cannot accommodate a 6-mg system, transdermal dosage can be initiated at 4 mg once daily administered as one system delivering 4 mg/24 hours. After 3–4 weeks of daily system application, dosage should be adjusted according to serum testosterone concentrations obtained 2–4 hours after application of a transdermal system.

Topical Gel Dosage

Topical testosterone is commercially available as a 1% gel in unit-dose packets (AndroGel®) containing a 25- or 50-mg dose (2.5 or 5 g of gel, respectively) or in unit-dose tubes (Testim®) containing a 50-mg dose (5 g of gel). For the treatment of male hypogonadism, the usual initial dosage of testosterone gel 1% is the entire contents of a packet containing 50 mg of testosterone (5 g of gel) applied topically once daily, preferably in the morning; this dose delivers about 5 mg of testosterone systemically. Dosage should be adjusted according to serum testosterone concentrations obtained approximately 14 days after initiating daily application of the gel. If serum testosterone concentrations are below the normal range or the clinical response is inadequate, the dosage can be increased initially to 75 mg of testosterone (7.5 g of gel) and, if necessary, subsequently to 100 mg of testosterone (10 g of gel).

[burlyman30]

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