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Testosterone Replacement, Low T, HCG, & Beyond
Testosterone Side Effect Management
Clinical Use of Aromatase Inhibitors in Adult Males
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<blockquote data-quote="madman" data-source="post: 132356" data-attributes="member: 13851"><p><span style="font-size: 26px"><strong>Aromatase inhibitors in men: effects and therapeutic options</strong></span></p><p></p><p></p><p></p><p></p><p><span style="font-size: 18px"><strong>Aromatase inhibitors</strong></span></p><p>Aromatase inhibitors are classified as either steroidal or nonsteroidal, or as first, second or third generation. Steroidal inhibitors such as formestane and exemestane inhibit aromatase activity by mimicking the substrate androstenedione. Nonsteroidal enzyme inhibitors such as anastrozole and letrozole inhibit enzyme activity by binding with the heme iron of the enzyme. First-generation aromatase inhibitors such as aminoglutethimide are relatively weak and nonspecific; they can also block other steroidogenic enzymes necessitating adrenal steroid supplementation. Third-generation inhibitors such as letrozole and anastrozole are potent and do not inhibit related enzymes. They are well tolerated and apart from their effects on estrogen metabolism their use does not appear to be associated with important side effects in postmenopausal women [<a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3143915/#B27" target="_blank">27</a>]. <strong>Although aromatase inhibition by anastrozole and letrozole is reported to be close to 100%,</strong> <strong><span style="color: rgb(184, 49, 47)">administration of these inhibitors to men will not suppress plasma estradiol levels completely</span></strong>. In men third-generation aromatase inhibitors will decrease the mean plasma estradiol/testosterone ratio by 77% [<a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3143915/#B28" target="_blank">28</a>,<a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3143915/#B29" target="_blank">29</a>]. This finding probably relates to the high plasma concentrations of testosterone, a major precursor for estradiol synthesis in adult men. <span style="color: rgb(0, 0, 0)"><strong>As </strong></span><span style="color: rgb(184, 49, 47)"><strong>aromatase inhibition is dose dependent</strong></span><span style="color: rgb(0, 0, 0)"><strong> it has been suggested that aromatase is </strong></span><span style="color: rgb(184, 49, 47)"><strong>less suppressed in the testis </strong></span><span style="color: rgb(0, 0, 0)"><strong>compared to adipose and muscle tissue, explaining the</strong></span><span style="color: rgb(184, 49, 47)"><strong> incomplete efficacy</strong></span><span style="color: rgb(0, 0, 0)"><strong> of aromatase inhibition in men</strong>. </span>Aromatase activity is high in the testes and the molar ratio of testosterone to letrozole is much higher in the testes compared with adipose and muscle tissue. When testicular testosterone and estradiol synthesis are suppressed and testosterone is administered exogenously in combination with letrozole, however, the estradiol/testosterone ratio is suppressed by 81% [<a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3143915/#B30" target="_blank">30</a>], which is only marginally different from the suppression of this ratio in intact men after treatment with letrozole. This incomplete suppression may be regarded as advantageous for it prevents excessive reduction of estrogen levels in men and the possible associated adverse effects. In postmenopausal women with breast carcinoma, long-term use of potent aromatase inhibitors reduces circulating estradiol levels by 88% [<a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3143915/#B31" target="_blank">31</a>] and is associated with adverse effects on bone [<a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3143915/#B2" target="_blank">2</a>,<a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3143915/#B3" target="_blank">3</a>]. Due to the much higher estrogen levels in treated men it remains to be determined whether this also holds true for men.</p><p></p><p></p><p></p><p></p><p></p><p></p><p> True and the take home point.....<strong><span style="color: rgb(184, 49, 47)">"administration of these inhibitors to men will not suppress plasma estradiol levels completely"</span></strong></p></blockquote><p></p>
[QUOTE="madman, post: 132356, member: 13851"] [SIZE=26px][B]Aromatase inhibitors in men: effects and therapeutic options[/B][/SIZE] [SIZE=18px][B]Aromatase inhibitors[/B][/SIZE] Aromatase inhibitors are classified as either steroidal or nonsteroidal, or as first, second or third generation. Steroidal inhibitors such as formestane and exemestane inhibit aromatase activity by mimicking the substrate androstenedione. Nonsteroidal enzyme inhibitors such as anastrozole and letrozole inhibit enzyme activity by binding with the heme iron of the enzyme. First-generation aromatase inhibitors such as aminoglutethimide are relatively weak and nonspecific; they can also block other steroidogenic enzymes necessitating adrenal steroid supplementation. Third-generation inhibitors such as letrozole and anastrozole are potent and do not inhibit related enzymes. They are well tolerated and apart from their effects on estrogen metabolism their use does not appear to be associated with important side effects in postmenopausal women [[URL='https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3143915/#B27']27[/URL]]. [B]Although aromatase inhibition by anastrozole and letrozole is reported to be close to 100%,[/B] [B][COLOR=rgb(184, 49, 47)]administration of these inhibitors to men will not suppress plasma estradiol levels completely[/COLOR][/B]. In men third-generation aromatase inhibitors will decrease the mean plasma estradiol/testosterone ratio by 77% [[URL='https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3143915/#B28']28[/URL],[URL='https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3143915/#B29']29[/URL]]. This finding probably relates to the high plasma concentrations of testosterone, a major precursor for estradiol synthesis in adult men. [COLOR=rgb(0, 0, 0)][B]As [/B][/COLOR][COLOR=rgb(184, 49, 47)][B]aromatase inhibition is dose dependent[/B][/COLOR][COLOR=rgb(0, 0, 0)][B] it has been suggested that aromatase is [/B][/COLOR][COLOR=rgb(184, 49, 47)][B]less suppressed in the testis [/B][/COLOR][COLOR=rgb(0, 0, 0)][B]compared to adipose and muscle tissue, explaining the[/B][/COLOR][COLOR=rgb(184, 49, 47)][B] incomplete efficacy[/B][/COLOR][COLOR=rgb(0, 0, 0)][B] of aromatase inhibition in men[/B]. [/COLOR]Aromatase activity is high in the testes and the molar ratio of testosterone to letrozole is much higher in the testes compared with adipose and muscle tissue. When testicular testosterone and estradiol synthesis are suppressed and testosterone is administered exogenously in combination with letrozole, however, the estradiol/testosterone ratio is suppressed by 81% [[URL='https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3143915/#B30']30[/URL]], which is only marginally different from the suppression of this ratio in intact men after treatment with letrozole. This incomplete suppression may be regarded as advantageous for it prevents excessive reduction of estrogen levels in men and the possible associated adverse effects. In postmenopausal women with breast carcinoma, long-term use of potent aromatase inhibitors reduces circulating estradiol levels by 88% [[URL='https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3143915/#B31']31[/URL]] and is associated with adverse effects on bone [[URL='https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3143915/#B2']2[/URL],[URL='https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3143915/#B3']3[/URL]]. Due to the much higher estrogen levels in treated men it remains to be determined whether this also holds true for men. True and the take home point.....[B][COLOR=rgb(184, 49, 47)]"administration of these inhibitors to men will not suppress plasma estradiol levels completely"[/COLOR][/B] [/QUOTE]
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Testosterone Replacement, Low T, HCG, & Beyond
Testosterone Side Effect Management
Clinical Use of Aromatase Inhibitors in Adult Males
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