PEBC Treatment Planning 6

Question 1

A 68-year-old patient with CKD stage 3b (eGFR 32 mL/min/1.73m²), type 2 diabetes, and heart failure with reduced ejection fraction (HFrEF, LVEF 35%) presents for medication review. Current medications include metformin 1000 mg BID, lisinopril 10 mg daily, and furosemide 40 mg daily. Which treatment plan adjustment is MOST appropriate?

Accepted Answer

Discontinue metformin; add insulin glargine; switch lisinopril to sacubitril/valsartan

Answer

At eGFR <30, metformin is contraindicated (lactic acidosis risk) and SGLT2 inhibitors (empagliflozin, dapagliflozin) lose glycemic efficacy and are generally not recommended below eGFR 30-45 (depending on agent). For HFrEF, sacubitril/valsartan (ARNI) reduces mortality and is preferred over ACE inhibitors in stable patients — the PARADIGM-HF trial demonstrated superiority. Insulin is appropriate for glucose control at this eGFR. While a beta-blocker (carvedilol) is also indicated in HFrEF, option C addresses the more critical and immediate safety issue (stopping metformin) while optimizing HF pharmacotherapy.

Question 2

A pharmacist is developing a treatment plan for a 55-year-old woman with treatment-resistant depression (failed 2 adequate SSRI trials and 1 SNRI trial at therapeutic doses for ≥6 weeks each). She has a history of well-controlled hypertension on amlodipine. Which augmentation or switch strategy is MOST evidence-based as a next step?

Accepted Answer

Augment with aripiprazole 2–5 mg daily as adjunctive therapy

Answer

Atypical antipsychotic augmentation (aripiprazole, quetiapine, olanzapine) is a first-line, well-supported strategy for treatment-resistant depression after multiple antidepressant failures, per CANMAT guidelines. Lithium augmentation is evidence-based but requires more intensive monitoring (renal function, thyroid, narrow therapeutic index). Bupropion is not absolutely contraindicated in controlled hypertension and could be considered, but augmentation is preferred over switching after 3 failed trials. MAOIs like phenelzine carry significant dietary restrictions, drug interactions, and safety risks, making them a last-resort option. Aripiprazole augmentation has strong RCT evidence and is Health Canada–approved for this indication.

Question 3

A 72-year-old male with atrial fibrillation (CHA₂DS₂-VASc score = 4) and a prosthetic mechanical mitral valve is currently on warfarin (INR target 2.5–3.5, consistently therapeutic). His cardiologist asks about switching to a direct oral anticoagulant (DOAC) to simplify monitoring. What is the MOST appropriate pharmacist recommendation?

Accepted Answer

Do not switch — DOACs are contraindicated in mechanical heart valves; continue warfarin

Answer

Mechanical prosthetic heart valves represent an absolute contraindication to DOACs. The RE-ALIGN trial evaluating dabigatran in mechanical valve patients was terminated early due to excess thromboembolic events and bleeding compared to warfarin. No DOAC is approved or safe for this indication. Warfarin remains the only anticoagulant with demonstrated efficacy for patients with mechanical heart valves. The INR target for a mechanical mitral valve is typically 2.5–3.5, which this patient is achieving — there is no clinical reason to change. The pharmacist should advise the cardiologist against switching.

Question 4

A treatment plan is being developed for a 45-year-old HIV-positive patient newly started on dolutegravir/abacavir/lamivudine (DTG/ABC/3TC). He also has latent TB and is being initiated on rifampin-based LTBI treatment. What is the MOST appropriate adjustment?

Accepted Answer

Increase dolutegravir dose to 50 mg BID due to rifampin induction of UGT1A1/CYP3A4

Answer

Rifampin is a potent inducer of UGT1A1 and CYP3A4, which significantly reduces dolutegravir plasma concentrations (by ~75%). When rifampin cannot be avoided, the recommended strategy is to double the dolutegravir dose to 50 mg BID to compensate for increased metabolism. This is reflected in DHHS and WHO HIV treatment guidelines. Rifabutin is less potent as an inducer and is preferred when treating active TB with a DOAC-based regimen, but for LTBI treatment with rifampin, the dose adjustment approach is standard. Changing the NRTI backbone does not address the pharmacokinetic interaction, which is specific to the integrase inhibitor.

Question 5

A pharmacist reviews the treatment plan for a 58-year-old woman with chronic migraine (≥15 headache days/month, ≥8 of which are migraine) who has failed topiramate and amitriptyline for prevention. She has a BMI of 38 and reports significant fatigue. Which preventive agent represents the MOST appropriate next step based on current evidence and her clinical profile?

Accepted Answer

Erenumab 70 mg SC monthly — CGRP receptor antagonist with favorable profile

Answer

After failure of two standard-of-care preventives (topiramate and amitriptyline), erenumab — a CGRP receptor monoclonal antibody — is indicated for chronic migraine prevention. In Canada, CGRP-pathway agents (erenumab, fremanezumab, galcanezumab) are approved specifically for patients who have failed or are intolerant to ≥2 preventive agents. Erenumab is weight-neutral (important given BMI 38), does not cause the fatigue worsening seen with beta-blockers, and avoids valproic acid's teratogenicity/weight gain concerns. Valproic acid is effective but associated with weight gain and is teratogenic — poor fit for this patient's profile. Propranolol can worsen fatigue and is typically first- or second-line, not third-line.

PEBC - Pharmacy Examining Board of Canada Practice Test

PEBC - Pharmacy Examining Board of Canada Practice Test

PEBC Treatment Planning 6