Pharmacology Questions for the CHPN Exam — Practice Free

The WHO principle By the Clock dictates that persistent pain requires scheduled (around-the-clock) dosing rather than PRN-only administration. The goal is to maintain a therapeutic serum level to prevent pain from recurring. PRN doses (10-15% of the total daily dose) should be reserved for breakthrough pain. HPCC Exam Tip: Distinguish between persistent pain (needs scheduled meds) and episodic pain (needs PRN). Common distractor: Increasing the PRN dose instead of scheduling it.

1. PO Morphine TDD = 120 mg. 2. Convert to IV (3:1 ratio): 120 / 3 = 40 mg IV/24hr. 3. Apply 50% reduction for safety: 40 mg x 0.50 = 20 mg IV/24hr. 4. Calculate hourly rate: 20 mg / 24 hours = 0.83 mg/hr. Exam Tip: Pay close attention to the order of operations. Convert the dose first, apply the safety reduction, and then divide by 24 to get the hourly rate. Common distractor: 1.6 mg/hr (forgetting the 50% reduction).

1) Hepatotoxicity (monitor LFTs, especially in the first 6 months) and 2) Pancreatitis (monitor for severe abdominal pain, nausea, and vomiting). Additionally, monitor for thrombocytopenia (platelet counts). HPCC Tip: While less common than gabapentinoids, Valproate is tested for its high-risk toxicity profile in multi-organ failure.

Current evidence (including major Cochrane reviews) does NOT support nebulized opioids as superior or even equal to systemic (oral/parenteral) administration for dyspnea. It is generally not recommended as a first-line or standard practice due to unpredictable absorption and lack of proven efficacy. Exam Tip: HPCC questions focus on evidence-based practice. While some clinicians use nebulized opioids anecdotally, the correct exam answer usually prioritizes oral or IV/SC routes because systemic opioids have a much stronger evidence base for reducing the sensation of breathlessness.

Metoclopramide is a prokinetic agent that increases gastric emptying and upper GI motility. In a complete MBO, stimulating peristalsis against a fixed mechanical barrier increases intraluminal pressure. **Clinical Rationale:** This can lead to severe colicky (cramping) abdominal pain and increases the risk of gastrointestinal perforation. **Exam Tip:** If the obstruction is *partial* and the goal is to maintain movement, Metoclopramide might be used cautiously, but for the CHPN exam, complete obstruction + prokinetic is a major red flag.