ERLONIX (ERLOTINIB) 100MG 30's

ERLONIX contains erlotinib, a small-molecule inhibitor of the epidermal growth factor receptor (EGFR) tyrosine kinase. EGFR is overexpressed or mutated in many non-small cell lung cancers (NSCLCs), particularly adenocarcinomas. Activating mutations in EGFR (most commonly exon 19 deletions and exon 21 L858R point mutations) render the tumour highly sensitive to EGFR inhibition.

ERLONIX is indicated for:

·       first-line treatment of locally advanced or metastatic NSCLC with confirmed EGFR activating mutations

·       maintenance treatment of locally advanced or metastatic NSCLC with stable disease after four cycles of first-line platinum-based chemotherapy

·       second-line or subsequent treatment of locally advanced or metastatic NSCLC after failure of at least one prior chemotherapy regimen.

The 100 mg tablet is used when dose reduction from the standard 150 mg dose is required due to toxicity.

The standard dose of erlotinib for NSCLC is 150 mg once daily. The 100 mg tablet is a dose-reduced formulation for patients experiencing significant toxicity (typically rash or diarrhoea) on 150 mg.

Administration

•       Take once daily at the same time, on an empty stomach — at least 1 hour before or 2 hours after food.

•       Swallow whole with water.

•       If a dose is missed and the next dose is more than 12 hours away, take the missed dose. If less than 12 hours until the next dose, skip the missed dose.

Drug-Food Interaction

Erlotinib absorption is significantly increased when taken with food (high-fat meal increases AUC by ~100%). Consistent fasting before dosing maintains predictable drug levels. Grapefruit and grapefruit juice inhibit CYP3A4 and increase erlotinib exposure — avoid.

Very Common Side Effects (more than 1 in 10 patients)

•       Rash / acneiform dermatitis — occurs in up to 75% of patients. Paradoxically, rash severity correlates with treatment efficacy. Usually appears in the first 2 weeks on face, chest, and back.

•       Diarrhoea — often mild-moderate; requires adequate hydration.

•       Fatigue.

•       Decreased appetite, nausea.

Serious Side Effects

•       Interstitial lung disease (ILD) / pneumonitis — sudden onset dyspnoea, cough, fever. Can be fatal. Incidence approximately 1–3%. Stop erlotinib immediately if suspected; do not rechallenge.

•       Hepatotoxicity — elevated liver enzymes, hepatic failure (rare). Monitor LFTs.

•       Gastrointestinal perforation — rare; risk higher in patients on corticosteroids, NSAIDs, or with prior GI tract involvement by tumour.

•       Severe skin reactions — Stevens-Johnson syndrome, toxic epidermal necrolysis (very rare).

•       Ocular disorders — keratitis, corneal perforation.

EGFR Mutation Testing — Mandatory Before Use

ERLONIX is most effective in EGFR-mutation-positive NSCLC. Before prescribing in the first-line setting, confirm EGFR mutation status (exon 19 deletion, L858R, or other sensitising mutation) by validated molecular testing on tumour tissue or plasma (liquid biopsy). In unselected NSCLC, erlotinib has no survival benefit over chemotherapy.

Interstitial Lung Disease

ILD is the most serious potentially fatal toxicity of erlotinib. Patients presenting with new or progressive dyspnoea, cough, or fever should have erlotinib withheld while ILD is investigated with CT chest and pulmonology review. If ILD is confirmed, permanently discontinue. Do not rechallenge. Manage with systemic corticosteroids.

Rash Management

Grade 1 (localised, mild): topical antibiotics (clindamycin gel), topical corticosteroids, oral doxycycline 100 mg twice daily prophylactically. Grade 2 (moderate, more widespread): add oral antibiotics; consider dose reduction if affecting quality of life. Grade 3–4 (severe, intolerable): interrupt erlotinib; resume at reduced dose after resolution to Grade 1.

Smoking

Smoking is a strong inducer of CYP1A1/1A2 and significantly reduces erlotinib plasma levels. Current smokers may require higher doses (up to 300 mg/day). Counsel all patients strongly to stop smoking, not only for lung cancer prognosis but also to ensure adequate drug exposure.

•       Proton pump inhibitors (omeprazole, lansoprazole) and H2 blockers — raise gastric pH, reducing erlotinib absorption by up to 50%; avoid PPIs; if antacid needed, use aluminium/magnesium hydroxide (separate by 4 hours) or H2 blockers (take erlotinib 10 hours after or 2 hours before).

•       Strong CYP3A4 inducers (rifampicin, phenytoin, carbamazepine, St John's Wort) — dramatically reduce erlotinib plasma levels; avoid combination; if unavoidable, increase erlotinib dose.

•       Strong CYP3A4 inhibitors (ketoconazole, itraconazole, clarithromycin, ritonavir) — significantly increase erlotinib exposure; reduce erlotinib dose.

•       Warfarin — erlotinib may elevate INR; monitor closely.

•       Grapefruit juice — inhibits CYP3A4; avoid throughout treatment.

•       Tobacco smoking — potent CYP1A induction reduces erlotinib by ~40%; encourage cessation; dose increase may be needed in smokers.

•       Store below 25 degrees Celsius.

•       Keep in original packaging, away from moisture.

•       Keep out of reach of children and pregnant women.

•       Do not use after the expiry date.

ERLONIX is a prescription-only medicine (POM) in Kenya, prescribed by consultant oncologists for appropriately selected patients with EGFR-mutation-positive NSCLC or other approved indications.

Molecular testing for EGFR status must be documented before prescribing in the first-line setting.

Rash Grading and Management Algorithm

•       Grade 1 (localised, no symptoms): continue erlotinib; start topical clindamycin 1% gel and oral doxycycline 100 mg twice daily.

•       Grade 2 (moderate, widespread, tolerable): continue erlotinib; topical + oral antibiotics; emollients; sunscreen.

•       Grade 2 (intolerable) or Grade 3: reduce dose by one level; if no improvement in 2 weeks at reduced dose, consider discontinuation.

•       Grade 4 (life-threatening): permanently discontinue.

Monitoring

•       LFTs: every 4 weeks for 3 months then every 3 months.

•       Renal function: baseline and at clinical discretion.

•       CT chest: at baseline, after 8–12 weeks; then every 3 months for response assessment.

Resistance and Subsequent Therapy

Most EGFR-mutant NSCLC patients develop resistance to erlotinib after a median of 9–14 months. The most common mechanism is the T790M secondary mutation. On progression, retest with liquid biopsy or repeat biopsy for T790M status. T790M-positive: use osimertinib (third-generation EGFR TKI). T790M-negative: consider chemotherapy or clinical trial.

Why is skin rash considered a good sign with ERLONIX?

Studies have consistently shown that patients who develop an acneiform rash on erlotinib tend to have better treatment responses and longer survival than those who do not. The rash is thought to occur because erlotinib is hitting EGFR in skin cells (which also express EGFR), suggesting the drug is at effective levels in the body. This does not mean you should avoid treating the rash — it can and should be managed to maintain quality of life while continuing therapy.

Why must I take ERLONIX on an empty stomach?

Taking erlotinib with food, especially a high-fat meal, significantly increases the amount of drug absorbed — sometimes doubling it. This unpredictable variation in absorption can lead to excessive drug levels and worsened side effects. To ensure consistent and predictable dosing, erlotinib must be taken at least 1 hour before or 2 hours after eating.

What should I do if I develop sudden breathlessness while on ERLONIX?

Stop taking ERLONIX immediately and contact your oncology team or go to the hospital urgently. Sudden breathlessness, a new dry cough, or fever during erlotinib treatment could be a sign of interstitial lung disease (ILD) — a rare but potentially life-threatening inflammation of the lungs. Erlotinib will be withheld while an urgent CT scan and chest assessment are performed.