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Home > Health Conditions > Breast Cancer > Femara.

Femara (letrozole) - 1/01

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For Aromatization (in males):

  • Effects of transdermal testosterone gel or an aromatase inhibitor on serum concentration and pulsatility of growth hormone in older men with age-related low testosterone - Metabolism. 2017 Apr;69:143-147 - "Thirty-seven men, ≥65years with total testosterone <350ng/dL were randomized to 5g transdermal testosterone gel (TT), 1mg oral aromatase inhibitor (AI) or placebo daily for 12months ... At 6months, IGF-1 significantly increased by Δ 15.3±10.3ng/ml in the TT-group compared to placebo (P=0.03). Both intervention groups significantly increased GH pulse frequency (TT-group, P=0.04; AI-group, P=0.05) compared to placebo. The GH secretory-burst mode (duration) significantly decreased in the TT-group (P=0.0018) compared to placebo while it remained unchanged in the AI-group" - Note:  Everything I've read over the years seems to indicate that low dose Femara is a better way to go than testosterone replacement (which increases estrogen as much as testosterone percentage wise).
  • Effects of Transdermal Testosterone Gel or an Aromatase Inhibitor on Prostate Volume in older men - J Clin Endocrinol Metab. 2016 Mar 7 - "Randomization to 5 g transdermal testosterone gel (TT), 1 mg oral aromatase inhibitor (AI) or placebo daily for 12 months ... lower urinary tract symptoms (LUTS) score ... Serum testosterone levels increased in both intervention groups; estradiol levels increased in the TT-group while it decreased in the AI-group. At 12 months, prostate volume significantly increased (4.5±1.76 cc, p<0.05) only in the TT group. Increase in PSA levels were seen in both intervention groups at 6 months (p<0.01 and p<0.001). LUTS score increased only in the TT group (p<0.05)"
  • Restoring testosterone rather than replacing it helps safeguard a man's fertility - Science Daily, 10/27/15 - "One of the basic tenets in medicine is to do no harm. As this study has shown in a randomized, double-blind, double-dummy, placebo-controlled manner, exogenous testosterone therapy with Androgel can clearly decrease sperm production and potentially impact fertility ... This study confirmed that Enclomiphene can maintain spermatogenesis while restoring testosterone levels to normal" - Note:  It just seems like Femara (letrozole) is a better way to go but I'm not a doctor.
  • Letrozole is a promising new treatment of male infertility - Science Daily, 3/7/14 - "Some recently published studies have suggested that in men with obesity-related low testosterone, a low dose of letrozole can normalize testosterone levels ... Doctors think obesity can cause infertility in men because excess fat results in too much estrogen. The body's aromatase enzyme, which is more prevalent in fat, converts androgens (male hormones, such as testosterone) into estrogen. Letrozole inhibits this action of aromatase ... The men received a 2.5-milligram letrozole pill every week"
  • Successful use of aromatase inhibitor letrozole in NOA with an elevated FSH level: a case report - Andrologia. 2013 Jun 26 - "We present the case of an infertile man with small testes and an elevated FSH level, which was diagnosed as NOA, hypospermatogenesis proven by testicular biopsy. After taking letrozole for 3 months, semen analyses by computer-aided sperm analysis present that this man had normal spermatogenesis"
  • Drugs for hair loss and benign prostatic hyperplasia may result in loss of libido, erectile dysfunction in men - Science Daily, 1/11/11 - "5a-reductase inhibitors (5a-RIs), while improving urinary symptoms in patients with benign prostatic hyperplasia (BPH) and possible hair loss prevention, produces significant adverse effects in some individuals including loss of libido, erectile dysfunction (ED), ejaculatory dysfunction and potential depression" - Note:  That goes back and forth.  One study claimed that finasteride improved sex after after six months of taking it.  Regarding gynaecomastia, if you're taking low dose letrozole to increase testosterone and to prevent aromatization it may also help prevent gynaecomastia.
    • Prostate Drug May Not Dim Sex - WebMD, 6/26/07 - "Six months after the men started taking their assigned drugs, the survey scores were about three points higher for the men taking Proscar. By the end of the study, that gap narrowed to about two points"
    • Prostate Drug Doesn't Limit Sexual Function In Most Men - Science Daily, 7/19/07 - "The study suggests that finasteride will cause little or no sexual dysfunction for most men who decide to take it"
    • Ask a Medical Question - Can letrozole cure gynecomastia - JustAnswer - "Letrozole may be effective in preventing and reversing the gynaecomastia provided it is used early enough in steroid induced gynaecomastia" - I believe the recommended dose is something like a quarter tablet every three days but don't quote me on it.  That's what I take.
  • Aromatase Inhibition Offers Little Benefit, Possible Harm to Men With Lo... - Medscape, 12/22/09 - "The inescapable conclusion from these data is that the 50% increase in testosterone levels was trumped by the much more modest 20% reduction in estradiol levels, leading to negative skeletal effects of anastrozole therapy in aging men" - Note:  I'm not sure that thought this though thoroughly.  Mortally in men is best when estrogen is around 25pg/mL.  I suspect that most have higher estrogen than that.  See:

    • High, Low Estradiol Levels and Mortality in Men With Systolic HF - Medscape, 5/19/09 - "Both low and high serum levels of estradiol, compared with mid-range levels, are significantly and independently associated with increased all-cause mortality in men with chronic systolic heart failure"
      Serum Estradiol Concentration Quintiles as Predictors of All-Cause Mortality in Men (With Quintile 3 as the Reference Group)
      Parameter Quintile 1 Quintile 2 Quintile 3 Quintile 4 Quintile 5
      Estradiol concentration (pg/mL) <12.903 12.90–21.79 21.80–30.11 30.12–37.39 >37.40
      3-y survival* (%) 44.6 65.8 82.4 79.0 63.6
      Quintile as mortality predictor,* HR (95% CI) vs quintile 3 4.17 (2.33–7.45) 2.15 (1.16–3.99) -- 1.22 (0.64–2.31) 2.33 (1.30–4.18)
      HR= hazard ratio
  • High, Low Estradiol Levels and Mortality in Men With Systolic HF - Medscape, 5/19/09 - "Both low and high serum levels of estradiol, compared with mid-range levels, are significantly and independently associated with increased all-cause mortality in men with chronic systolic heart failure" - Note:  See my aromatization page for ways to reduce it.  I take a quarter tablet of letrozole every day.  See letrozole at OffshoreRx1.com.
  • Serum Estradiol Concentration Quintiles as Predictors of All-Cause Mortality in Men (With Quintile 3 as the Reference Group)
    Parameter Quintile 1 Quintile 2 Quintile 3 Quintile 4 Quintile 5
    Estradiol concentration (pg/mL) <12.903 12.90–21.79 21.80–30.11 30.12–37.39 >37.40
    3-y survival* (%) 44.6 65.8 82.4 79.0 63.6
    Quintile as mortality predictor,* HR (95% CI) vs quintile 3 4.17 (2.33–7.45) 2.15 (1.16–3.99) -- 1.22 (0.64–2.31) 2.33 (1.30–4.18)
    HR= hazard ratio
  • Obesity Linked To Hormone Imbalance That Impacts Sexual Quality Of Life - Science Daily, 3/3/09 - "In our study population, we found that lower testosterone levels and diminished ratings for sexual quality of life were correlated with increased BMI ... Subjects who lost weight through bariatric surgery experienced a reduction in estradiol levels, an increase in testosterone levels and an increase in ratings of sexual quality of life" - See my aromatization page
  • Short-term aromatase inhibition: effects on glucose metabolism and serum leptin levels in young and elderly men - Eur J Endocrinol. 2008 Dec 2 - "Ten elderly and nine young healthy men were randomized to receive letrozole 2.5 mg daily or placebo for 28 days in a crossover design. Results: Both in young and elderly men, active treatment significantly increased serum testosterone (+128 and +99%, resp.) and decreased estradiol levels (-41 and -62%, resp.). Fasting glucose and insulin levels decreased in young men after active intervention (-7 and -37%, resp.) compared to placebo. Leptin levels fell markedly in both age groups (-24 and -25%, resp.), while adiponectin levels were not affected by the intervention. Lipid profile was slightly impaired in both groups, with increasing LDL-cholesterol levels (+14%) in the younger age group and 10% lower levels of ApoA1 in the elderly. A decline in IGF-1 levels (-15%) was observed in the younger age group. No changes in weight or BMI were observed in either young or old men" - See letrozole at OffshoreRx1.com.
  • Letrozole once a week normalizes serum testosterone in obesity-related male hypogonadism - Eur J Endocrinol. 2008 May;158(5):741-7 - "Isolated hypogonadotropic hypogonadism (IHH) is frequently observed in severely obese men, probably as a result of increased estradiol (E(2)) production and E(2)-mediated negative feedback on pituitary LH secretion. Aromatase inhibitors can reverse this process ... treated with 2.5 mg letrozole once a week for 6 months ... Six weeks of treatment reduced total E(2) from 123+/-11 to 58+/-7 pmol/l (P<0.001, mean+/-s.e.m.), and increased serum LH from 4.4+/-0.6 to 11.1+/-1.5 U/l (P<0.001). Total testosterone rose from 5.9+/-0.5 to 19.6+/-1.4 nmol/l (P<0.001), and free testosterone from 163+/-13 to 604+/-50 pmol/l (P<0.001). Total testosterone rose to within the normal range in all subjects, whereas free testosterone rose to supraphysiological levels in 7 out of 12 men ... Letrozole 2.5 mg once a week produced a sustained normalization of serum total testosterone in obese men with IHH. However, free testosterone frequently rose to supraphysiological levels. Therefore, a starting dose <2.5 mg once a week is recommended" - See Femara (letrozole) at OffshoreRX.
  • Comparative assessment in young and elderly men of the gonadotropin response to aromatase inhibition - J Clin Endocrinol Metab. 2005 Oct;90(10):5717-22 - "As assessed after 28 d of treatment, letrozole lowered E2 by 46% in the young men (P = 0.002) and 62% in the elderly men (P < 0.001). In both age groups, letrozole, but not placebo, significantly increased LH levels (339 and 323% in the young and the elderly, respectively) and T (146 and 99%, respectively) (P value of young vs. elderly was not significant). Under letrozole, peak LH response to GnRH was 152 and 52% increase from baseline in young and older men, respectively"
  • Letrozole normalizes serum testosterone in severely obese men with hypogonadotropic hypogonadism - Diabetes Obes Metab. 2005 May;7(3):211-5 - "Six weeks of treatment decreased serum estradiol from 120 +/- 20 to 70 +/- 9 pmol/l (p = 0.006). None of the subjects developed an estradiol level of less than 40 pmol/l. LH increased from 4.5 +/- 0.8 to 14.8 +/- 2.3 U/l (p < 0.001). Total testosterone rose from 7.5 +/- 1.0 to 23.8 +/- 3.0 nmol/l (p < 0.001) without a concomitant change in sex hormone-binding globulin level. Those treated with Letrozole 17.5 mg per week had an excessive LH response" - Note:  A half tablet per day would be 8.75 mg/week.  I believe 40 pmol/l of estradiol is 11.54 pg/mL and the normal value for men is 10 to 52 pg/mL (Quest says 10 to 50).  The way I read that, testosterone tripled.  See Femara at International Anti-aging Systems or Letrozole 2.5mg (Generic Equivalent of Femara 2.5mg ), at OffshoreRx1.com.
  • Influence of letrozole and anastrozole on total body aromatization and plasma estrogen levels in postmenopausal breast cancer patients evaluated in a randomized, cross-over study - J Clin Oncol. 2002 Feb 1;20(3):751-7 - "estrone (E(1)), estradiol (E(2)), and estrone sulfate (E(1)S) ... Treatment with anastrozole suppressed plasma levels of E(1), E(2), and E(1)S by a mean of 81.0%, 84.9%, and 93.5%, respectively, whereas treatment with letrozole caused a corresponding decrease of 84.3%, 87.8% and 98.0%, respectively. The suppression of E(1) and E(1)S was found to be significantly better during treatment with letrozole compared with anastrozole"
  • Open dose-finding study of a new potent and selective nonsteroidal aromatase inhibitor, CGS 20 267, in healthy male subjects - J Clin Endocrinol Metab. 1993 Aug;77(2):319-23 - "A reduction in estradiol levels by about 30% from baseline was observed at the lowest dose (0.02 mg)" - CGS 20 267 is Letrozole.
  • Letrozole-Femara - isteroids.com - "Letrozole is probably the most powerful Aromatase Inhibitor used by athletes today"
  • Femara (Letrozole) clinical pharmacology - RxList.com - "Letrozole's terminal elimination half-life is about 2 days and steady-state plasma concentration after daily 2.5 mg dosing is reached in 2-6 weeks"

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