Hydroxyurea Capsule 500 mg

Description

Hydroxyurea 500 mg capsules contain the active pharmaceutical ingredient hydroxyurea, a cytotoxic antimetabolite medication. It appears as a white crystalline powder enclosed in a capsule, often with a distinct color (e.g., purple cap and pink body for some brands). It is taken orally and works by interfering with cell growth, making it effective in treating certain cancers and blood disorders.

Advantages

Oral Administration: Convenient for long-term use at home, improving patient adherence compared to injectable therapies.
Broad Spectrum of Use: Effective in managing various conditions, including certain leukemias, solid tumors, and specific blood disorders.
Reduces Crisis Episodes in Sickle Cell Disease: Significantly reduces the frequency and severity of painful vaso-occlusive crises and the need for blood transfusions in patients with sickle cell anemia. It works by increasing fetal hemoglobin (HbF) levels, which helps prevent red blood cells from sickling.
Synergistic with Radiation: Can enhance the effectiveness of radiation therapy in certain cancers (e.g., head and neck cancers).
Reduces Blood Cell Counts: Effectively controls excessive production of abnormal white blood cells and platelets in myeloproliferative disorders.

Uses

Hydroxyurea Capsule 500 mg is primarily used for the treatment of:

Chronic Myeloid Leukemia (CML): To control the excessive production of abnormal white blood cells.
Sickle Cell Disease (SCD): To reduce the frequency of painful crises and the need for blood transfusions in adult and pediatric patients (typically 9 months of age and older) with recurrent moderate to severe painful crises.
Locally Advanced Squamous Cell Carcinomas of the Head and Neck (excluding lip): Often used in combination with concurrent chemoradiation to enhance therapeutic outcomes.
Polycythemia Vera and Essential Thrombocythemia: Other myeloproliferative disorders where it helps to lower high red blood cell and/or platelet counts.

Nature

Hydroxyurea is a cytotoxic antimetabolite agent. Its primary mechanism of action involves:

Ribonucleotide Reductase Inhibition: Hydroxyurea is a potent and reversible inhibitor of ribonucleotide reductase (RR). RR is an enzyme critical for DNA synthesis, as it catalyzes the conversion of ribonucleotides to deoxyribonucleotides, which are the essential building blocks for DNA. By inhibiting RR, hydroxyurea depletes the intracellular pools of deoxyribonucleotide triphosphates.
DNA Synthesis Inhibition: The depletion of deoxyribonucleotides directly inhibits DNA synthesis, particularly in rapidly dividing cells. This effect leads to cell cycle arrest in the S-phase (synthesis phase) and ultimately results in cell death. This is the primary mechanism by which it acts as an anti-cancer agent, affecting highly proliferative cancer cells.
Increased Fetal Hemoglobin (HbF) in Sickle Cell Disease: In patients with sickle cell disease, hydroxyurea induces the production of fetal hemoglobin (HbF). HbF interferes with the polymerization of hemoglobin S (HbS), which is responsible for the sickling of red blood cells. By increasing HbF, hydroxyurea helps to:
- Reduce red blood cell sickling.
- Improve red blood cell flexibility and hydration.
- Enhance blood flow and oxygen delivery.
- Decrease the frequency and severity of painful vaso-occlusive crises and other complications (e.g., acute chest syndrome).
Myelosuppression: Due to its inhibitory effect on DNA synthesis, hydroxyurea also suppresses bone marrow activity, leading to reduced production of white blood cells (leukopenia), platelets (thrombocytopenia), and red blood cells (anemia). This myelosuppression is a common and expected side effect, and blood counts are closely monitored during therapy.

Storage

Room Temperature: Store Hydroxyurea Capsule 500 mg at controlled room temperature, typically between 20∘C to 25∘C (68∘F to 77∘F). Some manufacturers may specify storage below 30∘C.
Protect from Light and Moisture: Keep the capsules in their original, tightly closed container or blister pack. It is essential to protect them from direct light, excessive heat, and humidity. Do not store in bathrooms or near a sink.
Do Not Open, Break, or Chew: Capsules should be swallowed whole. Do NOT open, break, or chew the capsules, as exposure to the powder can be harmful. Caregivers should wear disposable gloves when handling the capsules or the bottle.
Proper Disposal: Dispose of any unused or expired medication according to local hazardous waste disposal guidelines for cytotoxic drugs. Do not flush down the toilet or throw in household trash.
Check Expiry Date: Always check the expiry date printed on the packaging. Do not use the medication after this date.