# Nolvadex (Tamoxifen)

*Also known as: Tamoxifen, Nolva, SERM*

SERM used in PCT and on-cycle gynecomastia management. Active metabolite endoxifen.

## Overview

Nolvadex (tamoxifen) is a selective estrogen receptor modulator developed for estrogen-receptor-positive breast cancer and widely used in post-cycle therapy and on-cycle gynecomastia management. It acts as an estrogen antagonist at breast tissue and a partial agonist elsewhere, blocking estradiol at the mammary receptor while its active metabolite endoxifen, generated via CYP2D6, carries much of the clinical effect. The compound has a roughly 47-hour half-life for the parent and a much longer effective duration once active metabolites reach steady state, supporting once-daily oral dosing, and bioavailability is limited at roughly 15%. It is generally preferred over aromatase inhibitors for managing established gynecomastia symptoms because it targets the breast receptor directly rather than crashing systemic estradiol. Harm reduction centers on knowing that CYP2D6 polymorphisms and strong CYP2D6 inhibitors reduce endoxifen formation, on monitoring for VTE risk and vision changes with extended use, and on reserving it for symptom or PCT contexts guided by bloodwork.

## Pharmacokinetics

- **Model tier:** advanced
- **Half-life:** 2.0 days (47.400000000000006 hours)
- **Cmax:** 200 ng/mL
- **Tmax:** 0.3 days
- **Bioavailability:** 15%

## Dosing

- **Default dose:** 20 mg
- **Typical range:** 10–40 mg
- **Units:** ng/mL

## Source

- **Label:** FDA Nolvadex biopharm review
- **URL:** https://www.accessdata.fda.gov/drugsatfda_docs/nda/2002/21109_Nolvadex_biopharmr.pdf

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**Canonical URL:** https://anabolicdex.com/compounds/nolvadex
**Plot:** https://anabolicdex.com/plot?compound=nolvadex