Generic Name

Erlotinib Hydrochloride

---

Classification

FDA Approved Indications

• Non-small cell lung cancer (NSCLC)

Mechanism of Action

Erlotinib inhibits the tyrosine kinase activity of the epidermal growth factor receptor (EGFR), blocking downstream signaling pathways involved in tumor cell proliferation and survival.

Dosage and Administration

Adult: Initially 150 mg once daily, orally, on an empty stomach. Dose adjustments based on tolerability and response.

Pediatric: Not approved for pediatric use.

Geriatric: Use with caution; no specific dosage adjustment required but consider age-related organ function.

Renal Impairment: No specific adjustment recommended.

Hepatic Impairment: Use with caution; monitor liver function, dose adjustments may be necessary.

Pharmacokinetics

Absorption: Well absorbed orally, peak plasma levels in 4 hours.

Distribution: Extensively distributed into tissues; plasma protein binding approximately 93%.

Metabolism: Primarily metabolized in the liver via CYP3A4, CYP1A2, and CYP 2C8.

Excretion: Excreted mainly via feces (85%); minor renal excretion.

Half Life: Approximately 36 hours.

Contraindications

• Hypersensitivity to Erlotinib or any component of the formulation.

Precautions

• Risk of interstitial lung disease (ILD); monitor respiratory status.
• Liver toxicity; monitor liver enzymes.
• Skin rash and diarrhea are common adverse effects.
• Pregnancy category D; teratogenic. Women should use effective contraception.
• Photosensitivity; advise sun protection.

Adverse Reactions - Common

• Rash (Frequent)
• Diarrhea (Frequent)
• Fatigue (Common)
• Nausea (Common)

Adverse Reactions - Serious

• Interstitial lung disease (ILD) (Less common but serious)
• Hepatotoxicity (Rare)
• Severe dermatologic reactions (Rare)
• GI perforation (Rare)

Drug-Drug Interactions

• CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin) increase Erlotinib levels.
• CYP3A4 inducers (e.g., rifampin) decrease Erlotinib levels.

Drug-Food Interactions

• Grapefruit or grapefruit juice may increase Erlotinib levels.

Drug-Herb Interactions

• St. John’s Wort may decrease Erlotinib levels.

Nursing Implications

Patient/Family Teaching

• Take medication exactly as prescribed.
• Report unusual side effects, especially skin rash, diarrhea, or respiratory issues.
• Use effective contraception.
• Avoid sunlight and protect skin from UV exposure.
• Notify immediately if shortness of breath or chest pain occurs.

Special Considerations

Black Box Warnings:

• Interstitial lung disease (ILD) usually occurs within the first few months of therapy.
• Gastrointestinal perforation, usually associated with severe inflammatory processes.

Genetic Factors: EGFR mutation status influences response; testing recommended.

Lab Test Interference: May cause false elevations in serum alkaline phosphatase.

Overdose Management

Signs/Symptoms: Severe diarrhea, skin rash, vomiting.

Treatment: Supportive care, including hydration. No specific antidote; activated charcoal if ingestion is recent. Dialysis is not effective due to extensive tissue binding.

Storage and Handling

Storage: Store at room temperature (15–30°C), away from moisture and light.

Stability: Stable as per manufacturer until expiration date.