Methotrexate (MTX) is a versatile medication prescribed for various conditions, from certain cancers to autoimmune diseases like rheumatoid arthritis and psoriasis. Its administration method directly impacts effectiveness and safety, guiding appropriate treatment management.
Oral Administration
Oral methotrexate is commonly prescribed for chronic conditions such as rheumatoid arthritis or psoriasis. It is available in tablet or liquid form. Patients typically take methotrexate orally once a week, often on the same day, and it can be taken with or without food. For instance, a common starting dose for rheumatoid arthritis is 7.5mg once weekly, which can be adjusted by a doctor.
Adherence to the prescribed frequency and dosage helps prevent serious side effects. For those who find swallowing tablets difficult, pharmacists may advise dispersing them in water, though crushing tablets is generally discouraged unless specifically instructed.
Injectable Administration
Methotrexate can also be administered via subcutaneous (under the skin) or intramuscular (into the muscle) injections. These routes are often chosen for better absorption, to avoid stomach upset, or for higher doses not absorbed well orally. Subcutaneous injections are typically given in fatty tissue areas, such as the abdomen or thighs. Intramuscular injections can be given in the upper arm or thigh.
When self-administering, patients should clean the injection site and rotate sites each week to prevent skin irritation. After use, needles and syringes must be disposed of in a puncture-resistant sharps container.
Intravenous and Intrathecal Administration
Intravenous (IV) and intrathecal (IT) administrations of methotrexate are typically reserved for more severe conditions, particularly certain cancers like leukemia and lymphoma. These methods are performed by healthcare professionals in a clinical setting. IV administration involves delivering the medication directly into a vein as an infusion, allowing for rapid and widespread distribution throughout the body.
Intrathecal administration involves injecting methotrexate directly into the cerebrospinal fluid (CSF) surrounding the spinal cord or brain, often through a lumbar puncture or an implanted reservoir. This specialized route ensures the medication reaches the central nervous system to treat or prevent conditions like meningeal leukemia. The direct delivery bypasses the blood-brain barrier, which can block many medications from reaching this area.
Important Practicalities of Administration
Proper storage of methotrexate maintains its effectiveness. Oral tablets and pre-filled syringes are usually stored at room temperature, away from heat, moisture, and direct light. Some injectable forms, especially after the first use, may require refrigeration and have a limited use period, such as 30 days. Methotrexate is considered a hazardous drug, so handling precautions, such as wearing gloves when preparing liquid forms, are recommended to prevent skin contact.
If a dose is missed, patients are generally advised to take it as soon as they remember, provided it’s within one to two days of the scheduled dose. Never double a dose to make up for a missed one, as this can lead to serious complications. Patients should communicate with their healthcare providers regarding any concerns, side effects, or accidental overdose. Regular blood tests are typically performed to monitor liver and kidney function and blood counts, which helps ensure the medication is being managed safely.