Fosfestrol – Targeted Therapy

Fosfestrol is a synthetic estrogenic agent, chemically identified as diethylstilbestrol diphosphate. It is a "prodrug" specifically developed for the targeted therapy of hormone-dependent prostate neoplasms. The primary pharmacological value of fosfestrol lies in its ability to target tumor tissue while minimizing systemic estrogenic effects during the initial stages of metabolism.

The mechanism of action of fosfestrol is unique, utilizing the high activity of the acid phosphatase enzyme within prostate cancer cells. Following administration, the drug undergoes dephosphorylation directly within the tumor tissue and its metastases under the influence of this enzyme, releasing active diethylstilbestrol. This creates a high local concentration of estrogen that inhibits cancer cell division. Additionally, the drug exerts a powerful antiandrogenic effect by inhibiting the secretion of pituitary gonadotropic hormones, leading to a sharp decline in endogenous testosterone levels.

Fosfestrol also possesses direct cytotoxic activity against tumor cells that is independent of hormone receptors, allowing its use even when resistance to standard hormonal therapy has developed.

Wikipedia page
Fosfestrol

Indications

Fosfestrol is primarily used in onco-urological practice for the treatment of specific conditions:

  • Prostate Cancer: therapy for progressive, locally advanced, or metastatic prostate cancer (especially in late stages).
  • Hormone-Refractory Prostate Cancer: treatment of patients for whom standard androgen blockade or surgical castration has ceased to provide a therapeutic effect.
  • Tumor Recurrence: management of recurrent forms of the disease following radiation therapy or prostatectomy.
  • Bone Metastases: reduction of pain and slowing the growth of metastatic foci in bone tissue associated with prostate cancer.

Dosage and administration

The fosfestrol treatment regimen is individually tailored based on disease severity and the method of administration (intravenous or oral).

  • Intravenous Administration (Intensive Phase): typically begins with 600–1200 mg per day via slow infusion for the first 5–10 days to achieve a rapid effect.
  • Maintenance Therapy: after symptom reduction, the dose is gradually decreased to 300 mg 1–3 times weekly intravenously, or transitioned to oral tablet intake.
  • Oral Intake: the initial dose is 100–200 mg three times daily, followed by individual selection of a maintenance dose.
  • Administration Specifics: intravenous injections must be performed very slowly (over 5–10 minutes) under medical supervision due to the risk of acute vascular reactions.
  • Duration of Treatment: therapy is usually long-term, with regular monitoring of prostate-specific antigen (PSA) levels and acid phosphatase activity.

The use of fosfestrol is impermissible in the presence of the following clinical contraindications:

  • Thromboembolic Diseases: active thrombophlebitis, pulmonary embolism, or a history of myocardial infarction (estrogens increase coagulation risk).
  • Severe Liver Disease: acute hepatitis, cirrhosis, or significant hepatic impairment.
  • Cardiovascular Pathology: severe congestive heart failure and uncontrolled arterial hypertension.
  • Individual Intolerance: hypersensitivity to fosfestrol or any of the excipients in the medication.
  • Contraindications for Women and Children: the drug is intended exclusively for the treatment of men; use in women and children is not indicated.

The use of fosfestrol may be accompanied by a range of side effects characteristic of high-dose estrogens:

  • Cardiovascular System: fluid retention (edema), increased risk of thrombosis, and the development or exacerbation of heart failure.
  • Endocrine Disorders: gynecomastia (breast enlargement), nipple tenderness, decreased libido, and erectile dysfunction.
  • Gastrointestinal Tract: nausea, vomiting (especially with oral intake), loss of appetite, and in rare cases, impaired liver function.
  • Local Reactions: a sensation of burning or itching in the perineal and anal regions during or immediately after intravenous administration.
  • Neurological Symptoms: headache, mood swings, and increased fatigue.

Frequently Asked Questions

Fosfestrol is a synthetic estrogenic agent and a derivative of diethylstilbestrol. It acts as a "prodrug." Under the influence of the enzyme acid phosphatase, which is found in high concentrations in prostate cancer cells, fosfestrol is hydrolyzed to release active diethylstilbestrol directly within the tumor tissue.
The primary indication for fosfestrol is advanced prostate cancer, particularly in cases where the tumor has become resistant to other forms of hormone therapy. It helps alleviate bone pain caused by metastases and reduces prostate-specific antigen (PSA) levels.
Fosfestrol is available in two primary forms: oral tablets and intravenous (IV) injection solutions. IV administration is often used during the initial stages of treatment to achieve a rapid therapeutic effect (loading dose), followed by a transition to oral tablets for maintenance therapy.
Due to its potent estrogenic properties, men may experience gynecomastia (breast enlargement), decreased libido, fluid retention, and edema. There is also an increased risk of cardiovascular complications, such as thromboembolism; therefore, treatment must be closely monitored by a physician.
During IV administration of fosfestrol, some patients may experience a burning sensation or discomfort in the perineal area or at metastatic sites immediately after the injection. This is a transient reaction caused by the rapid action of the active substance on phosphatase-rich tissues. To minimize discomfort, the solution should be infused slowly.

List of medicines by active substance Fosfestrol

-10%
Honvan 120 mg Zydus Celexa
View
Zydus Celexa

Honvan

Fosfestrol
120 mg
1978₴ 2197₴
✅ All products loaded (1)

Contact us

Choose a convenient way to contact

We work daily from 9:00 to 20:00