Singapore Drugs Database

Indication

Enzalutamide is indicated for the treatment of patients with metastatic castration-resistant prostate cancer who have previously received docetaxel.

Mechanism of Action

Enzalutamide is a competitive androgen receptor inhibitor that effects multiple stages of the signalling pathway. It is able to inhibit androgen binding to its receptor, androgen receptor nuclear translocation, and subsequent interaction with DNA. As a result, proliferation of prostate cancer cells decreases which ultimately leads to apoptosis and decreased tumour volume.

Pharmacokinetics

Absorption

The pharmacokinetic profile of enzalutamide and N-desmethyl enzalutamide (its major active metabolite) is described by a linear two-compartment model with first-order absorption. Enzalutamide also accumulates. Food does not affect its absorption. Tmax, prostate cancer patients = 1 hour (range of 0.5-3 hours); Cmax, steady state, enzalutamide = 16.6 μg/mL; Cmax, steady state, N-desmethyl enzalutamide = 12.7 μg/mL; Time to steady state, daily dosing = 28 days;

Distribution

Apparent volume of distribution (Vd/F), single oral dose = 110 L

Metabolism

Enzalutamide is hepatically metabolized, primarily by CYP2C8 and CYP3A4. The enzyme that converts enzalutamide to its active metabolite, N-desmethyl enzalutamide, is CYP2C8. The activity of N-desmethyl-enzalutamide is similar to that of the parent compound.

Elimination

Clearance

Apparent clearance (CL/F), single oral dose = 0.56 L/h (range of 0.33 - 1.02 L/h)

Toxicity

The most common adverse reactions (≥ 5%) are asthenia/fatigue, back pain, diarrhea, arthralgia, hot flush, peripheral edema, musculoskeletal pain, headache, upper respiratory infection, muscular weakness, dizziness, insomnia, lower respiratory infection, spinal cord compression and cauda equina syndrome, hematuria, paresthesia, anxiety, and hypertension.

Active Ingredient/Synonyms

Enzalutamide | Enzalutamide |