Tamoxifen
Ancillaries & recoveryAlso known as Nolvadex
An oestrogen receptor modulator: blocks the receptor in breast tissue while leaving circulating oestradiol alone.
How it works
Competes with oestradiol at the receptor, antagonist in breast tissue and agonist in bone and liver. At the pituitary it blocks oestrogen's negative feedback, which raises LH and FSH and drives the testes to produce again. That second effect is why it appears in recovery protocols.
In the body
Shape of a single dose, modelled as one compartment with first-order absorption. The peak is normalised to 100% because bioavailability and volume of distribution are not published for most of these compounds.
5 to 7 days for the parent drug; 144 hours is the midpoint. The active metabolite N-desmethyltamoxifen is longer still at around 14 days, so steady state takes weeks and the tail after stopping is long.
Your notes
Doses
20 to 40 mg daily, the approved range for breast cancer treatment and risk reduction.
10 to 20 mg daily, either for gynecomastia or as part of a recovery protocol after suppression. Neither use is an approved indication.
Side effects
- Hot flushes
- Nausea
- Visual disturbance, uncommon but a reason to stop and seek advice
- Raised risk of venous thromboembolism
- Mood changes
- Monitor: total and free testosterone, LH and FSH, if the purpose is recovery
Cautions
- History of deep vein thrombosis or pulmonary embolism
- Taking a second oestrogen receptor modulator at the same time
- Pregnancy
Status
Prescription-only. Approved for breast cancer, not for post-cycle recovery. Banned in sport at all times as a hormone and metabolic modulator.
Reference information for personal record-keeping. Not medical advice, and not a recommendation to use any of these compounds.