Pharmacokinetics of testosterone therapies in relation to diurnal variation of serum testosterone levels as men age.

BACKGROUND: To improve symptoms associated with testosterone deficiency, many testosterone therapies are available that aim to restore serum testosterone (T) levels to the normal physiologic range. The magnitude, frequency, and duration between peak and trough T concentrations vary with route of administration, and none reflect normal endogenous daily diurnal T variations. OBJECTIVE: To compare pharmacokinetic profiles of serum T from approved T formulations with endogenous diurnal T variations in young and older men, and to consider whether there may be value in mimicking the diurnal T rhythmicity with exogenous testosterone therapies as men age. MATERIALS AND METHODS: A literature search of studies examining the diurnal variation of endogenous T in healthy men and men with testosterone deficiency was performed using PubMed in January 2020. Additional searches for serum T pharmacokinetic profiles of various testosterone therapy formulations were also conducted. Prescribing information for various T formulations was also reviewed. DISCUSSION AND CONCLUSION: Endogenous diurnal T variation is well described and appears to be blunted naturally as men age. Men with testosterone deficiency lack diurnal T variation and exhibit a flatter T profile compared with eugonadal men. Some T replacement options provide intraday T level variations similar to normal circadian secretion, and others provide a flatter exposure profile reflective of depot release. Others provide profiles that exceed the frequency and physiologic range of the natural diurnal variation of T. All exogenous T replacement dosing targets an increase in average T levels to within the normal physiologic range and improves symptoms associated with low T, but no single testosterone therapy can exactly mimic the normal diurnal T patterns seen in younger men and the blunted circadian T secretion of older men.

Development and application of analytical procedures for the GC-MS/MS analysis of the sulfates metabolites of anabolic androgenic steroids: The pivotal role of chemical hydrolysis.

In this work, we present a gas-chromatography tandem mass spectrometry (GC-MS/MS) method for the identification of the sulfo-conjugate metabolites of pseudo-endogenous steroids (endogenous steroids when administered exogenously). We have preliminarily evaluated the performances of different preparations of sulfatases from Pseudomonas aeruginosa and Helix pomatia, characterized by various origins and catalytic activities, and compared the efficacy of the enzymatic hydrolysis with chemical hydrolysis, performed with a mixture of ethyl acetate, methanol, and sulphuric acid. A procedure for the selective isolation of steroid conjugates from the urine matrix has been designed and optimized, based on the "sequential" extraction of the glucuro-conjugated and of the sulfo-conjugated fractions, performed by two different direct methods, i.e. by ion paired extraction or solid-phase extraction. More specifically, the former method is based on the use of N,N-dimethylephedrinium bromide as the ion paired extraction reagent, while the latter on the use of WAX® (weak anion exchange) cartridges. The performance of the newly developed procedure has been assessed by the analysis of real urine excretion samples collected after the oral intake of a single dose of dehydroepiandrosterone (DHEA) or androstenedione (AED), measuring the concentration of epiandrosterone (EpiA) sulfate. Our results have shown the following: (i) although the yields of chemical hydrolysis and enzymatic hydrolysis are in some cases quite similar, the former is generally preferable since it results in the quantitative cleavage of sulfate moiety; (ii) ion paired extraction has been selected as the most reliable method for direct isolation of sulfate steroids from urine matrices; (iii) EpiA sulfate allows to prolong the detectability of DHEA and AED when compared to routinely used steroidal target compounds.

Importance of reversed-phase chromatographic parameters in predicting biopharmaceutical and pharmacokinetic descriptors on the group of androgen derivatives.

Nowadays the standard measure of lipophilicity, the logarithm of n-octanol-water partition coefficient, logP, is proposed to be replaced with chromatographic techniques. Chromatography techniques (reversed phase thin layer chromatography RPTLC and reversed phase thin layer chromatography RPHPLC) are the most widely used alternatives to the shake flask method. However, it is shown that, by changing the temperature or concentration of organic modifier in the chromatography experiment, it is possible to derive data matrix of retention parameters from which, by principle component analysis, structural characteristics of the examined molecules can be gained. The question may be asked which of the chromatography experimentally obtained and calculated parameters: capacity factor k, ΔGx (the change in Gibbs energy of binding of molecule for stationary phase), ΔHx (the change in enthalpy of binding of molecule for stationary phase) or ΔSx (the change in the entropy of binding of molecule for stationary phase) is the most suitable in describing hydrophobicity. The canonical correlation analysis (CCA) method is used to evaluate the importance of the n functions in explaining the variance of molecular descriptors connected to pharmaceutical processes and wherein molecule's hydrophobicity is expressed and possible differences between molecular descriptors with realistic conformations of the analyzed molecules steroid skeleton are discussed. Conformational analysis showed that structure of steroid skeleton in hydrophobicity is most completely described with k or ΔGx, and connection between conformation of the steroid skeleton and hydrophobicity to a lesser extent is projected on temperature dependence on ΔHx and similarly on ΔSx, so in describing molecules hydrophobicity it is necessary to observe entropic as well as enthalpic contribution together, expressed with ΔGx function. Canonical conformation analysis (CCA) showed that hydrophobicity contained in ΔGx and k explains 61% of variance represented in in silico descriptors. Analyzed molecular descriptors, derived from different molecules fragments don't map conformational specifics of those molecules in small groups so recommendation is to use them complementary with chromatographic data in describing hydrophobicity.

Lead evaluation of tetrahydroquinolines as nonsteroidal selective androgen receptor modulators for the treatment of osteoporosis.

Tetrahydroquinoline (THQ) was deemed to be a suitable scaffold for our nonsteroidal selective androgen receptor modulator (SARM) concept. We adapted the strategy of switching the antagonist function of cyano-group-containing THQ (CN-THQ) to the agonist function and optimized CN-THQ as an orally available drug candidate with suitable pharmacological and ADME profiles. Based on binding mode analyses and synthetic accessibility, we designed and synthesized a compound that possesses a para-substituted aromatic ring attached through an amide linker. The long-tail THQ derivative 6-acetamido-N-(2-(8-cyano-3a,4,5,9b-tetrahydro-3H-cyclopenta[c]quinolin-4-yl)-2-methylpropyl)nicotinamide (1 d), which bears a para-acetamide-substituted aromatic group, showed an appropriate in vitro biological profile, as expected. We considered that the large conformational change at Trp741 of the androgen receptor (AR) and the hydrogen bond between 1 d and helix 12 of the AR could maintain the structure of the AR in its agonist form; indeed, 1 d displays strong AR agonistic activity. Furthermore, 1 d showed an appropriate in vivo profile for use as an orally available SARM, displaying clear tissue selectivity, with a separation between its desirable osteoanabolic effect on femoral bone mineral density and its undesirable virilizing effects on the uterus and clitoral gland in a female osteoporosis model.

Long acting testosterone undecanoate therapy in men with hypogonadism: results of a pharmacokinetic clinical study.

PURPOSE: We determined the pharmacokinetics and safety of 750 mg long acting testosterone undecanoate given intramuscularly at 0, 4 and 14 weeks to men with hypogonadism. MATERIALS AND METHODS: A 24-week, single arm, open label, multicenter trial in 130 hypogonadal men 18 years or older who were screened for serum total testosterone less than 300 ng/dl was performed at 31 research sites in the United States between March and November 2007. Testosterone undecanoate (750 mg) was administered at baseline, and at weeks 4 and 14. Serum testosterone samples were collected on days 4, 7, 11, 14, 21, 28, 42, 56 and 70 following injection 3. Safety was assessed, eg biochemical markers and adverse events, secondary to testosterone undecanoate treatment. RESULTS: Of the 130 patients 116 with a mean +/- SE age of 54.2 +/- 0.90 years completed the 24-week trial. Following the week 14 injection mean +/- SD average serum testosterone was 494.9 +/- 141.46 ng/dl during the 70-day dosing interval and mean +/- SD maximum serum testosterone was 890.6 +/- 345.11 ng/dl with a mean concentration within the young healthy adult male range (300 to 1,000 ng/dl) in 94% of patients and a mean maximum concentration of below 1,500 ng/dl in 92%. Mean +/- SE hematocrit and hemoglobin increased from baseline to week 24 (43.3% +/- 0.32% to 45.7% +/- 0.35% and 14.6 +/- 0.11 to 15.5 +/- 0.13 gm/dl, respectively). Mean +/- SE prostate specific antigen increased from baseline to 24 weeks (1.0 +/- 0.08 to 1.3 +/- 0.10 ng/ml). No prostate cancer or gynecomastia was observed during this 24-week study. CONCLUSIONS: This 24-week clinical study demonstrated that 750 mg testosterone undecanoate depot injection administered intramuscularly at 0, 4 and 14 weeks achieves serum testosterone levels in the normal range during a 10-week dosing interval.

More than eight years' hands-on experience with the novel long-acting parenteral testosterone undecanoate.

Testosterone (T) as a compound for treatment of T deficiency has been available for almost 70 years, but the pharmaceutical formulations have been less than ideal. Traditionally, injectable T esters have been used for treatment, but they generate supranormal T levels shortly after the 2-3 weekly injection interval. T levels then decline very rapidly, becoming subnormal during the days preceding the next injection. The rapid fluctuations in plasma T are subjectively experienced as disagreeable. T undecanoate (TU) is a new injectable T preparation with a considerably better pharmacokinetic profile. After two initial injections separated by a 6-week interval, the following intervals between two injections are generally 12 weeks, eventually amounting to a total of four injections per year. Plasma T levels with this preparation are nearly always in the range of normal men, as are its metabolic products estradiol and dihydrotestosterone (DHT). It reverses the effects of hypogonadism on bone and muscle and metabolic parameters, and on sex functions. It is suitable for male contraception. Its safety profile is excellent because of the continuous normalcy of plasma T levels. No polycythemia has been observed and no adverse effects on lipid profiles. Prostate safety parameters are well within reference limits. TU is a valuable treatment option of androgen deficiency.

Pharmacokinetics of S-3-(4-acetylamino-phenoxy)-2-hydroxy-2-methyl-N-(4-nitro- 3-trifluoromethyl-phenyl)-propionamide in rats, a non-steroidal selective androgen receptor modulator.

1: S-3-(4-acetylamino-phenoxy)-2-hydroxy-2-methyl-N-(4-nitro-3-trifluoromethyl-phenyl)-propionamide (also known as S-4) is a non-steroidal selective androgen receptor modulator demonstrating tissue-selective androgenic and anabolic effects. The purpose of the present study was to examine the systemic pharmacokinetics, elimination and oral bioavailability of S-4 in rats. 2: Thirty-five male Sprague-Dawley rats weighing approximately 250 g were randomly assigned to one of seven treatment groups. Intravenous doses of 0.5, 1, 10, and 30 mg kg(-1) were given via a jugular catheter. Oral doses of 1, 10 and 30 mg kg(-1) were administered via gavage. Plasma concentrations were determined using a validated high-performance liquid chromatography or by a high-performance liquid chromatography/mass spectrometry method. 3: Clearances ranged between 1.0 and 2.1 ml min(-1) kg(-1) and varied with dose. The volume of distribution was approximately 0.448 l kg(-1) in all treatment groups. Oral bioavailability was also dose dependent, with the lower doses showing complete oral bioavailability. The half-life of S-4 over the dose range tested was between 2.6 and 5.3 h. 4: It was demonstrated that S-4 is rapidly absorbed, slowly cleared, and has a moderate volume of distribution in rats. The pharmacokinetics and oral bioavailability of S-4 indicate that it is an excellent candidate for clinical development.

A new oral testosterone undecanoate formulation.

Testosterone undecanoate has been available on the market for more than 20 years. This testosterone ester is used worldwide for oral treatment of male hypogonadism. So far, testosterone undecanoate has been dissolved in oleic acid, leading to inconvenient storage conditions. It will now be available in a new formulation with castor oil and propylene glycol laurate instead of oleic acid, thus improving storage conditions markedly (stable at room temperature for approximately 3 years). Pharmacokinetic and pharmacodynamic studies have demonstrated bioequivalence of the old and the new formulation of testosterone undecanoate. Therefore, the results of studies that were performed with the old formulation can be transferred to the clinical use of the new formulation. Controlled studies have shown its efficacy in the treatment of symptoms associated with reduced serum testosterone levels. In these cases testosterone undecanoate improves bone mineral density, quality of life, muscle mass, libido and mood. Further studies will help evaluate the efficacy and safety of the new formulation in the treatment of elderly men with late-onset hypogonadism.

Pharmacokinetics and degree of aromatization rather than total dose of different preparations determine the effects of testosterone: a nonhuman primate study in Macaca fascicularis.

Currently available testosterone (T) preparations differ substantially in their pharmacokinetic profile that might influence their androgenic properties in terms of suppression of the gonadal axis, effects on anabolic parameters, lipid metabolism, and erythropoiesis. The present work was undertaken to determine the physiological effects of three T preparations with different serum kinetics. Twenty adult male cynomolgus monkeys (Macaca fascicularis) were randomly assigned to receive treatment for 28 weeks with either T enanthate (TE) every 4 weeks, T buciclate (TB) every 7 weeks, or T undecanoate (TU) every 10 weeks or remaining untreated (controls). Each injection delivered 20 mg pure T per kilogram body weight. Pharmacokinetic profiles demonstrated higher peak levels of T for TE-treated animals; serum half-lives were longer for TU or TB. Estradiol levels (area under the curve) were significantly higher in TB vs TU or TE. All T regimens suppressed serum luteinizing hormone bioactivity and testicular volumes declined (all P <.001 vs controls). Sperm counts were markedly lowered in all animals but least in TE (P <.01 vs TB or TU). During recovery phase, return to normal for all three parameters occurred significantly earlier in TE-treated animals, followed by those given TU, compared with TB (all P <.001 between groups). Body weight increased significantly during T exposure. This effect was stronger and more sustained in TB vs TU or TE (both P <.001). Serum creatinine and hemoglobin increased with high significance in all T-treated animals (all P <.001 vs controls). The lowering impact of T on serum lipids was markedly stronger in the longer-acting T preparations in comparison with TE, as were effects on purine metabolism (all P <.001). The pattern of exposure and degree of aromatization rather than overall exposure to T determine its effects in the preclinical primate model. Both fluctuations of androgen concentrations and the conversion rate to estradiol influence gonadal suppression as well as metabolism. These results have to be considered in men receiving treatment for hypogonadism or regimens for hormonal contraception.

Plasma and urinary markers of oral testosterone undecanoate misuse.

Orally administered testosterone undecanoate (TU), an anabolic, androgenic steroid, can potentially be abused by athletes. Indirect evidence for detecting oral TU intake could be deduced from the changes in steroid profile post-administration. Direct evidence could be obtained by detection of unchanged TU in plasma. To this end, both urinary and plasma steroid profiles of six healthy male subjects given a single oral dose of 120 mg of TU were studied by gas chromatography/mass spectrometry (GC/MS) and gas chromatography/tandem mass spectrometry (GC/MS/MS). The increased concentration of glucuronidated testosterone in plasma appears to be the most characteristic sign of oral TU intake. The testosterone glucuronide (TG)/nonconjugated testosterone (T) ratio, TG/17-hydroxyprogesterone (17OHP) ratio, and TG/luteinizing hormone (LH) ratio were observed to be significantly elevated above their basal levels for 10 h, 10 h, and 6 h, respectively. Urinary ratios of TG/epitestosterone glucuronide (EG) were found to be higher than the cut-off value of 6 for the period 4 approximately 8 h post-administration, but only in three subjects. One subject failed to respond with respect to all of the above-mentioned indirect markers, as TG was not significantly increased in either plasma or urine. Unchanged TU was directly detected in plasma of all six subjects from 1 approximately 1.5 h to 4 approximately 6 h after oral TU intake by GC/MS/MS, providing unequivocal proof of exogenous testosterone intake. Distinct and complementary markers for detecting oral TU intake could be obtained from plasma and urine, respectively.

Intramuscular injection of testosterone undecanoate for the treatment of male hypogonadism: phase I studies.

OBJECTIVE: In the search for long-acting testosterone preparations suited for substitution therapy of hypogonadal men, testosterone undecanoate (TU) dissolved in either tea seed oil or castor oil was investigated. DESIGN: In study I, 1000 mg TU in tea seed oil (125 mg/ml) were injected in equal parts into the gluteal muscles of seven hypogonadal men. In study II, 1000 mg TU in castor oil (250 mg/ml) were injected into one gluteal muscle of 14 patients. RESULTS: In comparison with published data on testosterone enanthate, most widely used for i.m. injections, the kinetic profiles of both TU preparations showed extended half-lives and serum levels not exceeding the upper limit of normal. The castor oil preparation had a longer half-life than TU in tea seed oil (33.9+/-4.9 vs 20.9+/-6.0 days (mean pm S.E.M.)). CONCLUSION: The longer half-life and the smaller injection volume make TU in castor oil a strong candidate for further applications in substitution therapy and in trials for male contraception.

Pharmacokinetics of 7 alpha-methyl-19-nortestosterone (MENT) delivery using subdermal implants in healthy men.

We studied the pharmacokinetics of 7 alpha-methyl-19-nortestosterone (MENT), a potent synthetic androgen, administered by subdermal implants. The implants contained 112 +/- 4 mg of MENT acetate in a polyethylene vinyl acetate copolymer. MENT acetate released from the implants is rapidly hydrolyzed to MENT in vivo. Fifteen healthy Finnish men were randomized to have either one, two, or four implants inserted in the medial aspect of the upper arm. The implants remained in place for 4 weeks. Blood samples were obtained before implant insertion, 1, 2, 3, and 4 weeks after insertion, and 1 and 2 weeks after removal. Serum MENT concentrations were determined by gas chromatography with mass selective detection. The MENT levels attained in each implant group remained at a steady level during the 4 weeks of implant use. The mean steady state MENT concentrations in the one, two, and four implant groups were 0.6, 1.4, and 2.3 nmol/L, respectively. Serum MENT concentrations during implant use were clearly dose dependent; the between-subject effect of implants as well as the differences between each pair of groups were all statistically significant. The release rate of MENT from one, two, and four implants was calculated to be approximately 0.3, 0.8, and 1.3 mg/day, respectively. This study suggests that MENT acetate implants are a promising method for long-term androgen administration in hypogonadism and male contraception.

PIP: The authors studied the pharmacokinetics of 112 +or- 4 mg of MENT acetate in a polyethylene vinyl acetate copolymer. MENT acetate released from the implants is rapidly hydrolyzed to MENT in vivo. 15 healthy Finnish men were randomized to have either 1, 2, or 4 implants inserted in the medial aspect of the upper arm. The implants remained in place for 4 weeks. Blood samples were obtained before implant insertion, 1, 2, 3, and 4 weeks after insertion, and 1 and 2 weeks after removal. Serum MENT concentrations were determined by gas chromatography with mass selective detection. The MENT levels attained in each implant group remained at a steady level during the 4 weeks of implant use. The mean steady state MENT concentrations in the 1, 2, and 4 implant groups were 0.6, 1.4, and 2.3 nmol/l, respectively. Serum MENT concentrations during implant use were clearly dose dependent; the between-subject effect of implants as well as the differences between each pair of groups were all statistically significant. The release rate of MENT from 1, 2, and 4 implants was calculated to be approximately 0.3, 0.8, and 1.3 mg/day, respectively. The study suggests that MENT acetate implants are a promising method for long-term androgen administration in hypogonadism and male contraception.

[Pharmacokinetics and metabolism of synthetic androgen and anabolic hormone].

Esters of 17 beta position of testosterone and nandrolone gradually liberate their free forms into circulation, which are metabolized through usual androgen pathway. 17 beta-hydroxy-17 alpha-methyl compounds, used per os as androgenic and anabolic drugs, show complicated metabolism, including saturation of A ring, degradation of substituted radicals at A ring, hydroxylation at 6 and/or 16, and epimerization at 17. These metabolites are excreted as free or conjugated forms with glucuronidate and sulfate.

Androgen action in cultured dermal papilla cells from human hair follicles.

Androgens are major regulators of human hair growth with paradoxically different effects on hair follicles depending on their body site. They stimulate terminal growth in many regions including the face, have no effect on eyelashes, but may cause inhibition and balding on the scalp in genetically disposed individuals. How this occurs is unknown. However, androgens may act on the hair follicle via the cells of the dermal papilla; these would then influence the other cells of the hair follicle by altering the production of regulatory substances such as growth factors and/or extracellular matrix components. Therefore, primary lines of dermal papilla cells have been established from androgen-sensitive hair follicles, such as beard, and control, relatively androgen-independent, non-balding scalp cells and their mechanism of androgen action has been compared. Isolated beard dermal papillae were larger than those from scalp follicles. Although dermal papilla cells did not respond to in vitro androgens by alterations in growth, androgen-dependent dermal papilla cells contained higher levels of specific, low capacity, high affinity androgen receptors than non-balding scalp cells. The ability of the cells to metabolise testosterone to 5 alpha-dihydrotestosterone in culture also varied in parallel to that predicted from studies of hair growth in the 5 alpha-reductase deficiency syndrome. These results support the hypothesis that androgens act via the dermal papilla. They also show that dermal papilla cells retain differences in gene expression in culture which appear to correspond with their androgenic response in vivo. Further studies of such cells should help elucidate why bald men can grow beards!

History, chemistry and pharmacodynamics of anabolic-androgenic steroids.

It had been known for centuries that castration resulted in the loss of certain secondary male sex characteristics. The first inkling as to the cause of these changes were provided in 1849 by a prevention of the regression of the comb and wattles of capons by implantation of testis into the abdominal cavity of the castrated rooster. The results were correctly interpreted that the testis secreted a substance into the blood to regulate the development and maintenance of the male characteristics. The first active extract of testis, however, was not prepared until 1927. Shortly thereafter (1929), a similar type of activity was found in men's urine which was followed (1931) by the isolation of a pure substance, androsterone. A substance with the properties of the testis extract was quickly (1935) synthesized and proved to be identical to a pure substance, testosterone, obtained almost simultaneously from testis extract. Testosterone influences the growth, development, and function of practically every organ in the body. The chemically and endogenously modified steroids do not have parallel effects on the different biological properties of testosterone. Furthermore animal species and dose of steroid affect the response of the different organs. Many chemically modified steroids and some endogenous steroids of both the C19 and C21 series exhibit definite separation of undesirable biological effects.

Clinical assessment and urine testing for anabolic-androgenic steroid abuse and dependence.

The emerging epidemic of anabolic-androgenic steroid use, no longer confined to elite athletes, is associated with adverse health consequences for which users may seek treatment. As with other forms of drug abuse, patients may deny or hide their use of steroids while seeking treatment for bothersome side effects or other problems. Thus, clinicians may increasingly, but unknowingly, see patients who are using steroids. Early detection and treatment of steroid abuse and dependence is critical in order to prevent serious and potentially fatal consequences. Therefore, it is incumbent upon clinicians to know the signs and symptoms of using steroids, and to be familiar with the clinical indications for urine testing. Using case examples, the authors review the assessment of steroid abuse and dependence in clinical practice and illustrate the role of urine testing in the assessment process.

Validation of the exchange assay for the measurement of androgen receptors in human and dog prostates.

This study describes an exchange assay for measurement of cytosolic and nuclear androgen receptors (AR) in human and dog prostates. Efficient replacement of endogenously bound ligand from the receptor with [3H] mibolerone was achieved by incubation of cytosolic or nuclear fractions at 0 degree C for 72 h in the presence of 0.15M NaSCN and 15% sucrose. It was demonstrated that in the presence of the chaotropic salt rapid steroid dissociation took place at 0 degree C followed by [3H] mibolerone binding; sucrose protected the AR from denaturation by NaSCN. Combination of these two reagents, therefore, allowed quantitative androgen exchange at 0 degrees C. Receptors determined by this exchange procedure are specific for androgens, of high affinity (KD 2-5 nM), and sedimented on sucrose gradients as 4-4.6S entities. Use of [3H] mibolerone minimized interference from plasma proteins and reduced nonspecific binding. This exchange assay has now been applied to quantitation of cytosolic and nuclear AR in small tissue samples (50 mg). Thus it is possible to measure AR in tissue samples obtained by needle biopsies and attempt to correlate receptor values to clinical response of prostatic cancer patients.