Histrelin acetate

Histrelin acetate is a synthetic nonapeptide analog of gonadotropin-releasing hormone (GnRH) with potent agonist properties. It is used in medicine primarily for the treatment of hormone-sensitive cancers such as prostate cancer, and in the management of precocious puberty — a condition where children experience an early onset of puberty. Histrelin acetate works by initially increasing the levels of follicle-stimulating hormone (FSH) and luteinizing hormone (LH), but prolonged administration leads to a decrease in FSH and LH levels due to receptor downregulation, resulting in decreased testosterone and estrogen production.

Medical Uses

Histrelin acetate is utilized in two main therapeutic areas: the treatment of advanced prostate cancer and the management of central precocious puberty (CPP). In prostate cancer, the goal is to reduce testosterone levels, which can help in slowing the growth of the cancer. For CPP, histrelin acetate helps in delaying premature sexual development and slowing the rapid bone maturation which can lead to short stature in adulthood.

Administration

Histrelin acetate is administered as a subcutaneous implant. The implant, which is about the size of a matchstick, is placed under the skin in the upper arm and releases histrelin continuously for 12 months. This mode of administration ensures consistent drug levels in the bloodstream, making it an effective long-term therapy option.

Pharmacology

Histrelin acetate acts as a GnRH agonist. Upon initial administration, it causes a surge in LH and FSH levels, leading to a temporary increase in sex steroid hormones (testosterone and estrogen). However, with continuous exposure, it desensitizes the GnRH receptors in the pituitary gland, leading to a significant reduction in LH and FSH secretion. Consequently, the production of sex hormones is greatly reduced.

Side Effects

The use of histrelin acetate can lead to several side effects, which may include injection site reactions, hot flashes, headache, and mood changes. In the treatment of prostate cancer, reduced testosterone levels can also lead to decreased libido, erectile dysfunction, and fatigue. For children treated for precocious puberty, side effects may include injection site reactions and occasional headaches.

Contraindications

Histrelin acetate is contraindicated in patients with known hypersensitivity to the drug or any of its components. It should also be used with caution in patients with certain medical conditions such as uncontrolled diabetes, cardiovascular disease, and osteoporosis, as the reduction in sex hormone levels can exacerbate these conditions.

See Also

• Gonadotropin-releasing hormone agonist
• Prostate cancer
• Precocious puberty
• Follicle-stimulating hormone
• Luteinizing hormone