Letrozole is a competitive nonsteroidal aromatase inhibitor. Aromatase is an enzyme that ensures the conversion of androgens (synthesized in the adrenal glands) to estrone and estradiol in postmenopausal women. Considering that in some cases tumor tissue growth depends on the presence of estrogen, which in the postmenopausal period is formed mainly only with the participation of aromatase, the use of aromatase inhibitors allows to reduce estrogen levels and create conditions for tumor response to therapy.
Description of the drug
In animal experiments, the use of letrozole led to a decrease in uterine weight and regression of tumors (hormone-dependent) with efficacy similar to ovariectomy. At the same time, against the background of letrozole therapy (in contrast to ovariectomy) there is no increase in serum levels of follicle-stimulating hormone.
Letrozole selectively inhibits steroid production in the gonads without affecting the production of glucocorticosteroids and mineralocorticosteroids in the adrenal glands. The mechanism of inhibition of aromatase is realized due to competitive binding of letrozole with cytochrome P450 heme that results in decrease of estradiol biosynthesis in all body tissues. Against the background of letrozole therapy there is a decrease in serum levels of estradiol, estrone and estrone sulfate without significant effect on the synthesis of aldosterone and corticoids and thyroid hormones.
Letrozole is quickly absorbed in the digestive tract. Bioavailability reaches 99.9%, and food slightly reduces the absorption rate without significantly affecting the time to reach peak concentrations. About 60% of letrozole in serum is in bound state (mainly with albumin). The level of letrozole in leukocytes reaches 80% of the plasma level. Letrozole is slightly metabolized (about 82% of labeled letrozole in serum was unchanged), letrozole derivatives have no therapeutic activity. Metabolism occurs with the participation of P450 isoenzymes
Letrozole is well distributed in tissues, the volume of distribution reaches 1.87 ± 0.47 l/kg.
Letrozole is excreted by the kidneys. The elimination half-life is 2 days, the equilibrium concentrations at constant therapeutic doses are marked in 2-6 weeks of treatment (the equilibrium concentrations are about 7 times higher than concentrations obtained by single letrozole administration). However, the values of equilibrium concentrations are 1.5-2 times higher than the expected equilibrium concentrations that can be calculated considering concentrations after single doses (indicating a deviation from linear pharmacokinetics). Letrozole does not cumulate in the body (given the long maintenance time of equilibrium concentrations).
Is Tetrazole legal
The sale of Letrozole is legal in the US. It is a prescription drug that is used to treat breast cancer in women after menopause. The Food and Drug Administration (FDA) has approved it for this use. Letrozole is also being studied as a treatment for other cancers. Letrozole is widely available all over the world, with Femara being the most common brand. It is not a controlled substance in the United States, but you will need a prescription to get it legally. You will also find that Letrozole is widely available on the black market from anabolic steroid suppliers. It does not appear to be counterfeit. Of course, although it is not a controlled substance, buying it from an anabolic steroid supplier would be illegal in the United States.
Letrozole is also widely available from research chemical laboratories (RCL). RCL produces AI, SERM and various other uncontrolled items in liquid form and is legally allowed to sell them without a prescription, as long as it is for research purposes only. There are some high quality RCLs on the market, but they are much less than the low-grade ones. Regardless of which route you choose, you will find that getting Letrozole is very easy. Letrozole is a drug used to treat breast cancer. It is also approved by the Food and Drug Administration (FDA) for the treatment of infertility in women. Some people may try to buy. Letrozole online without a prescription. This is not legal or safe. The only way to get Letrozole legally is through a prescription from a doctor.
Countless people buy Letrozole online every day through anabolic steroid suppliers and RCLs. However, if you buy Letrozole from a steroid supplier that is in its original form in pills, you are breaking the law in the United States. As for the RCL, while the purchase is legal because of a loophole in the law, there are risks you need to be aware of. When you buy Letrozole online from RCL, there is a risk of buying a substandard product.
Low dosages are possible, but the most common problem is an unstable product. Also, if law enforcement wants to make this a problem, you will have to prove that this purchase was made for research. If you have anabolic steroids, they will be difficult to sell. The best way to buy Letrozole, given the quality and legality, will always be through a pharmacy with a prescription from your doctor. However, while it is possible, a prescription is not as much in demand as Arimidex.
Because of the laws that surround AIs such as Letrozole and anabolic steroids, you are advised to visit the sponsors at Steroid.com for your anabolic needs. The sponsors at Steroid can provide you with high quality anabolics without a prescription and legally. Those who suffer from low testosterone or suspect it because of the symptoms they may be exhibiting are strongly encouraged to visit the site if you require treatment and AI, such as Letrozole. Lowtestosterone.com can walk you through a complete low testosterone treatment plan and ensure that you get the treatment you need, the best products on the market and with a 100% legal guarantee.
How to use
Letrozole is prescribed only by the doctor in charge. The therapy with Letrozole must be supervised by a doctor. The doses and duration of therapy are determined individually and may vary depending on the nature and severity of the disease. The daily dose of 2.5 mg of Letrozole per day is usually prescribed in the regimen of adjuvant therapy. In this case, adjuvant and extended adjuvant therapy can last up to 5 years (or until the disease relapses)
After standard therapy with tamoxifen, patients should be monitored by a physician and continue therapy with letrozole for 4 years (or until relapse). Patients with metastases should be treated with letrozole until signs of disease progression become evident.
When using Letrozole in preoperative preparation the doctor should constantly monitor the patient’s condition. In elderly patients and in case of moderate or mild hepatic impairment the change of letrozole dose is not necessary.
Taking into account the risk of osteoporosis development against the background of Letrozole therapy, it is necessary to monitor the state of bone tissue in patients receiving treatment.