Free OCN Pharmacology Practice Questions with Answers

Tamoxifen (20 mg daily for 5 years) is the standard for premenopausal women. The ASCO/NCCN guidelines and the ONCC blueprint emphasize a 5-year Gail Model risk score of ≥1.7% as the threshold for discussing chemoprevention. Rational: Tamoxifen is a SERM that reduces the risk of ER+ invasive breast cancer by ~50%. It is the only FDA-approved agent for premenopausal risk reduction. Exam Tip: Note that the Gail Model does not account for paternal history or lobular carcinoma in situ (LCIS) as effectively as other models (like Tyrer-Cuzick), but 1.7% remains the magic number for the OCN exam.

Formula: Calvert Formula [Total Dose (mg) = Target AUC x (GFR + 25)]. Note: GFR is often estimated using the Cockcroft-Gault equation, capped at 125 mL/min. Dose-Limiting Toxicity: Myelosuppression, specifically thrombocytopenia. Clinical Pearl: Carboplatin is generally less nephrotoxic, ototoxic, and emetogenic than cisplatin, but causes more significant bone marrow suppression. Exam Tip: If a patient has a significant change in serum creatinine, the carboplatin dose may need recalculation because the dose is directly tied to renal function.

Vincristine is FATAL IF GIVEN INTRATHECALLY. It causes ascending myeloencephalopathy. Prevention: 1. MUST be dispensed in a minibag (never a syringe) to prevent accidental injection into the spinal column. 2. Labels must state FOR INTRAVENOUS USE ONLY. ONCC Tip: This is a Never Event. If it occurs, emergency neurosurgical intervention is required but rarely successful.

Osimertinib is a 3rd-generation TKI designed to target the T790M resistance mutation and has superior CNS penetration for brain metastases. Monitoring: Baseline and periodic ECGs for QTc prolongation and assessment for Left Ventricular Ejection Fraction (LVEF) decrease. Rationale: While more targeted, it still impacts cardiac signaling. Exam Strategy: Know that 3rd-gen TKIs bypass common resistance mechanisms (like T790M) of earlier generations and are now often used in the first-line setting as of 2026.

While both are NK1 receptor antagonists, Rolapitant is a moderate inhibitor of CYP2D6, whereas Aprepitant inhibits CYP3A4. This means Rolapitant does NOT interact with Dexamethasone (a CYP3A4 substrate), but it CAN increase concentrations of drugs like Tamoxifen or certain antidepressants metabolized by CYP2D6. Additionally, Rolapitant has an exceptionally long half-life (180 hours), meaning it is only administered once every 2 weeks. ONCC Focus: Understanding the unique CYP inhibition of Rolapitant compared to other NK1s.