Elagolix

MECHANISM OF ACTION

It works by binding to GnRH receptors in the pituitary gland, which inhibits the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH).

PHARMACOKINETICS

Absorption

Elagolix is rapidly absorbed after oral administration, with peak plasma concentrations (Cmax) typically reached within 1 to 2 hours. Its absorption is not significantly affected by food, although taking it with a high-fat meal may slightly reduce the rate of absorption without affecting overall exposure (AUC).

Distribution

Elagolix is widely distributed throughout the body after absorption. It is approximately 80% bound to plasma proteins, mainly albumin, which influences its free (active) concentration. The volume of distribution (Vd) is moderate, indicating that the drug distributes into tissues but remains largely in the plasma.

Metabolism

Elagolix is primarily metabolized in the liver by the cytochrome P450 enzyme CYP3A4. 

Elimination

Elagolix is eliminated primarily via the feces (about 67%) and to a lesser extent via urine (approximately 24%). Its terminal half-life is roughly 4 to 6 hours, allowing for once- or twice-daily oral dosing.

PHARMACODYNAMICS

Elagolix is a selective gonadotropin-releasing hormone (GnRH) receptor antagonist that rapidly and reversibly suppresses pituitary secretion of LH and FSH. This leads to a dose-dependent reduction in ovarian estrogen and progesterone production, which alleviates symptoms of endometriosis and reduces uterine fibroid–related bleeding.

ADMINISTRATION

Elagolix is administered orally in the form of tablets, typically once or twice daily depending on the indication and dose. It can be taken with or without food, although consistent timing is recommended to maintain stable hormone suppression.

DOSAGE AND STRENGTH

Elagolix is available as 150 mg and 200 mg oral tablets. For the treatment of endometriosis-related pain, it is typically prescribed as 150 mg once daily for partial estrogen suppression or 200 mg twice daily for near-complete suppression.

DRUG INTERACTIONS

Elagolix can interact with other medications mainly through CYP3A4 metabolism and drug transporters. Drugs that inhibit CYP3A4, such as ketoconazole, can increase Elagolix levels and the risk of side effects, while CYP3A4 inducers, like rifampin, can reduce its effectiveness.

FOOD INTERACTIONS

Elagolix can be taken with or without food, as food has minimal effect on its overall absorption. A high-fat meal may slightly reduce the rate of absorption, but it does not significantly affect the total exposure or effectiveness of the drug.

CONTRAINDICATIONS

Elagolix is contraindicated in patients who are pregnant or breastfeeding, in those with severe hepatic impairment, or in individuals with a known hypersensitivity to Elagolix or any component of its formulation. It should also be avoided in patients with unexplained vaginal bleeding until the underlying cause is identified.

SIDE EFFECTS

• Hot flashes 

• Headache 

• Nausea 

• Fatigue 

• Decreased bone mineral density 

• Menstrual irregularities 

• Mood changes 

• Insomnia

TOXICITY

Elagolix toxicity is rare when used at recommended doses, but excessive or prolonged use can lead to significant adverse effects, primarily due to excessive suppression of estrogen and progesterone. Potential toxic effects include severe bone mineral density loss, liver enzyme elevations, and increased risk of cardiovascular issues.