Buserelin

BRAND NAMES

• Suprefact – injection

• Suprecur – nasal spray

• Buserecur – injection

MECHANISM OF ACTION

Buserelin works by initially stimulating, then suppressing the pituitary gland, which lowers the body’s production of sex hormones like estrogen and testosterone. This makes it effective for treating hormone-sensitive conditions such as prostate cancer, endometriosis, and uterine fibroids.

PHARMACOKINETICS

Absorption

Buserelin is absorbed best through injections, which enter the bloodstream directly. Nasal sprays are absorbed less efficiently, with only a small amount reaching the body.

Distribution

The distribution of Buserelin refers to how it spreads in the body after absorption. Its volume of distribution (Vd) is approximately 16–22 liters, indicating it is mostly distributed in body fluids rather than fat tissue.

Metabolism

Buserelin is primarily metabolized in the liver and kidneys by enzymatic breakdown into smaller inactive peptides. Its metabolism is rapid, and only a small amount of the unchanged drug circulates in the bloodstream.

Excretion

Buserelin is mainly excreted through the urine as inactive metabolites, with a small portion eliminated in feces. Its elimination is relatively fast, which is why regular dosing is needed to maintain hormone suppression.

PHARMACODYNAMICS

Buserelin initially raises sex hormone levels by stimulating the pituitary, but with continued use, it suppresses hormone release, lowering estrogen and testosterone. This effect helps treat conditions like prostate cancer, endometriosis, and uterine fibroids.

ADMINISTRATION

Buserelin can be administered as a nasal spray or by subcutaneous/intramuscular injection, depending on the condition being treated and the desired hormone suppression.

DOSAGE AND STRENGTH

• Nasal spray: Usually 200–400 µg/day, divided into multiple sprays.

• Injection: Typically 500 µg to 3.75 mg/day or every few days, depending on the condition and protocol.

FOOD INTERACTIONS

Buserelin has no significant known food interactions, meaning it can be taken with or without food. However, following the prescribed administration route (nasal spray or injection) and schedule is important for effectiveness.

DRUG INTERACTIONS

• Anti-androgens or estrogens – may alter its effectiveness in hormone-sensitive conditions.

• Dopamine agonists/antagonists – can affect pituitary hormone release.

• Other GnRH analogs – using together may increase hormone suppression or side effects.

CONTRAINDICATIONS

Buserelin is contraindicated in:

• Pregnancy and breastfeeding

• Known hypersensitivity to Buserelin or other GnRH analogs

• Undiagnosed vaginal bleeding

• Severe liver or kidney impairment (use with caution)

• Hormone-dependent cancers not indicated for treatment with GnRH agonists

SIDE EFFECTS

• Hot flashes and sweating

• Headache and dizziness

• Nausea and vomiting

• Mood changes or depression

• Vaginal dryness or decreased libido

• Injection or nasal irritation

OVERDOSE

Buserelin overdose is rare and usually not life-threatening. Symptoms may include increased hormonal effects such as hot flashes, headache, nausea, or mood changes. There is no specific antidote, and treatment is mainly supportive and symptomatic, with medical supervision if needed.

TOXICITY

Buserelin has low systemic toxicity. Most adverse effects are related to hormone suppression, such as hot flashes, mood changes, or bone density loss with long-term use. Toxic reactions are uncommon, and serious organ damage is rare when used at prescribed doses.