Medication Overview: Proscar

Generic Name

Finasteride

Drug Class

5-alpha-reductase inhibitors

Indications

Benign Prostatic Hyperplasia

Proscar is primarily indicated for the treatment of benign prostatic hyperplasia (BPH), which is an enlargement of the prostate gland. BPH can lead to urinary symptoms such as increased frequency, difficulty in starting urination, and the need to urinate during the night. Finasteride works by reducing the size of the enlarged prostate, thereby relieving these symptoms.

Prostate Cancer Risk Reduction

Finasteride is sometimes used to lower the risk of prostate cancer. Although not its primary indication, clinician-directed usage has been noted in specific high-risk patient groups to reduce the likelihood of developing this malignancy. It should be noted that the overall benefit and risk profile should be carefully assessed in such cases.

Mechanism of Action

Inhibition of 5-alpha-reductase

Proscar (Finasteride) inhibits the enzyme 5-alpha-reductase, which is responsible for the conversion of testosterone into dihydrotestosterone (DHT). DHT plays a crucial role in the development and enlargement of the prostate. Reduction in DHT levels leads to decreased prostate size and consequent relief of BPH symptoms.

Long-term Effects on DHT

Continuous administration of Proscar results in sustained reduction of serum and intraprostatic DHT levels. This long-term inhibition can aid in consistent management of BPH symptoms by stabilizing or gradually reducing prostate volume over time.

Administration

Dosage

The standard dose for Proscar in treating BPH is 5 mg once a day. Administration should be consistent and may be independent of meals. Patients are generally recommended to take the medication at the same time each day to maintain even drug levels in the body.

Administration Route

Proscar is orally administered in the form of tablets. Patients should swallow the tablet whole with a glass of water. Crushing or splitting the tablet is not recommended, as it may affect the drug’s efficacy.

Pharmacokinetics

Absorption

Finasteride is well absorbed following oral administration, achieving peak plasma concentrations approximately 2 hours post-dose. The bioavailability of Finasteride is about 80%, indicating efficient absorption into the systemic circulation.

Distribution

Finasteride is extensively distributed throughout the body and has a volume of distribution of approximately 76 liters. It is approximately 90% bound to plasma proteins, mainly albumin, reflecting significant drug-protein affinity.

Metabolism

The primary site of Finasteride metabolism is the liver. Finasteride is metabolized by the cytochrome P450 enzyme system, specifically CYP3A4. This metabolism results in multiple inactive metabolites which are then excreted.

Elimination

Finasteride and its metabolites are primarily excreted via feces (57%) and urine (39%). The elimination half-life of Finasteride is approximately 6-8 hours in adults and may be prolonged in elderly patients.

Contraindications

Hypersensitivity

Proscar is contraindicated in patients with known hypersensitivity to Finasteride or any components of the formulation. Hypersensitivity reactions may include skin rashes, swelling, and difficulty breathing.

Female and Pediatric Use

Proscar is contraindicated for use in women and pediatric patients. In women, particularly those who are pregnant or may become pregnant, exposure to Finasteride can lead to potential teratogenic effects, including abnormalities in the genitalia of male fetuses. Pediatric patients benefit little from the pharmacological action of Finasteride, as it is designed to manage conditions linked to adult male hormones.

Drug Interactions

Cytochrome P450 Interactions

Proscar is metabolized primarily by CYP3A4 enzymes. Concomitant use of drugs that inhibit or induce CYP3A4 enzymes could potentially alter the metabolism of Finasteride. Careful consideration and monitoring might be warranted when combining Proscar with such agents.

Warfarin Interaction

Finasteride has been shown to affect warfarin’s anticoagulatory properties, potentially altering prothrombin time. Patients receiving both Finasteride and Warfarin should have their blood coagulation parameters closely monitored to avoid bleeding complications.

Side Effects

Common Side Effects

Some common side effects associated with Proscar include sexual dysfunction (reduced libido, erectile dysfunction), ejaculation disorders, and decreased semen volume. These effects are generally reversible upon discontinuation of the drug.

Psychiatric Effects

A small fraction of patients may experience psychiatric side effects such as depression and anxiety. These symptoms are rare but should be promptly addressed if they occur.

Mammary Changes

Some men may experience breast tenderness or enlargement and, in rare cases, gynecomastia. Regular monitoring and consultation with healthcare providers are advised if these symptoms develop.

Monitoring Parameters

Prostate-Specific Antigen

Regular measurement of prostate-specific antigen (PSA) levels is crucial in patients on Proscar therapy. PSA levels may decrease as prostate size diminishes, potentially impacting prostate cancer screenings and diagnoses. Adjustments in expected PSA values should be made accordingly.

Liver Function Tests

Routine liver function tests are recommended to assess the hepatic metabolism and identify any hepatic dysfunctions during long-term Proscar treatment. Unexplained liver function anomalies may necessitate dosage adjustments or discontinuation.

Urinary Function

Monitoring urinary flow rates and residual urine volumes assists in evaluating the therapeutic response and efficacy of Proscar in managing BPH symptoms. Regular follow-ups help in adjusting treatment strategies for optimized care.

Storage Conditions

Optimal Temperature

Store Proscar at controlled room temperature, specifically between 15-30°C (59-86°F), to maintain stability and efficacy. Exposure to excessively high or low temperatures should be avoided.

Light and Humidity

Proscar should be stored in a well-sealed container, protected from light and moisture. Prolonged exposure to these elements can degrade the medication, undermining its effectiveness.

Prescription Guidelines

Authorized Providers

Proscar should only be prescribed by healthcare providers experienced in treating BPH and related conditions. Providers must also be capable of interpreting monitoring parameters and adjusting treatment regimens as necessary.

Refill Policies

Refill policies for Proscar may vary based on the prescriber’s assessment of the patient’s condition and response to therapy. Regular consultations and evaluations are generally recommended for ongoing prescription renewal.

Clinical Studies

Efficacy Trials

Clinical trials have demonstrated Proscar’s efficacy in reducing prostate size and alleviating urinary symptoms associated with BPH. Studies indicate significant improvement in symptom scores and urinary flow rates compared to placebo.

Longitudinal Studies

Long-term studies have shown maintenance of therapeutic benefits with continued use of Proscar. Prolonged treatment correlates with sustained symptom relief and reduced need for surgical intervention in BPH patients.