Nurses Compass
Drug Guide
Pemetrexed
Classification
Therapeutic: Antineoplastic agent
Pharmacological: Antimetabolite
FDA Approved Indications
- Non-small cell lung cancer (NSCLC)
- Malignant pleural mesothelioma
Mechanism of Action
Pemetrexed is an antifolate chemotherapy agent that inhibits thymidylate synthase and other folate-dependent enzymes involved in purine and pyrimidine synthesis, leading to inhibition of DNA and RNA synthesis and cell death.
Dosage and Administration
Adult: Typically 500 mg/m² IV infusion on Day 1 of each 21-day cycle, as per specific treatment regimens.
Pediatric: Not commonly used in pediatric populations; dosing is based on body surface area and clinical judgment.
Geriatric: Dose adjustments are not typically required solely based on age, but caution is advised due to potential comorbidities.
Renal Impairment: Dose reduction or delay may be necessary; renal function should be assessed before each dose.
Hepatic Impairment: Use with caution; no specific dose adjustment recommended, but hepatic function should be monitored.
Pharmacokinetics
Absorption: Given IV, so absorption is not applicable.
Distribution: Widely distributed, crossing the blood-brain barrier minimally.
Metabolism: Minimal metabolism; primarily eliminated unchanged.
Excretion: Renally excreted, primarily unchanged.
Half Life: Approximately 3.5 hours.
Contraindications
- Hypersensitivity to pemetrexed or its components.
- Severe renal impairment (creatinine clearance < 45 mL/min).
Precautions
- Use in pregnancy and lactation should be avoided; women should use effective contraception during treatment.
- Monitor renal function closely.
- Patients should receive folic acid and vitamin B12 supplements before and during treatment to reduce toxicity.
Adverse Reactions - Common
- Myelosuppression (neutropenia, anemia, thrombocytopenia) (Common)
- Nausea, vomiting (Common)
- Fatigue (Common)
- Stomatitis (mouth ulcers) (Common)
Adverse Reactions - Serious
- Serious myelosuppression leading to infection or bleeding (Serious)
- Interstitial pulmonary disease or pneumonitis (Serious)
- Allergic reactions including rash, pruritus, anaphylaxis (Serious)
Drug-Drug Interactions
- Cisplatin (co-administration increases toxicity)
Drug-Food Interactions
- Avoid alcohol and live vaccines during treatment.
Drug-Herb Interactions
N/ANursing Implications
Assessment: Monitor blood counts, renal function, hepatic function, and hydration status before each dose.
Diagnoses:
- Risk for infection
- Imbalanced nutrition: less than body requirements
Implementation: Administer with folic acid and vitamin B12 as recommended. Ensure adequate hydration and monitor for toxicity.
Evaluation: Assess patient’s tolerance, blood counts, and organ functions regularly to modify therapy as needed.
Patient/Family Teaching
- Report signs of infection, bleeding, or allergic reactions.
- Maintain adequate hydration.
- Take folic acid and vitamin B12 supplements as prescribed.
- Avoid pregnancy during therapy and for at least 6 months after.
Special Considerations
Black Box Warnings:
- Potential for myelosuppression, which can be severe and lead to serious infections, bleeding, or neutropenic fever.
- Risk of pulmonary toxicity, including interstitial pneumonitis.
Genetic Factors: Vitamin B12 and folic acid deficiency may increase toxicity; supplementation recommended.
Lab Test Interference: May alter blood counts, renal and hepatic function tests.
Overdose Management
Signs/Symptoms: Severe myelosuppression, mucositis, or pulmonary toxicity.
Treatment: Supportive care; no specific antidote. Hematopoietic growth factors or transfusions may be required.
Storage and Handling
Storage: Store at room temperature away from moisture and light.
Stability: Stable for the duration of the labeled expiration date when stored properly.