GPhC Clinical Therapeutics & BNF Guidelines 3 — Questions and Answers
Question 1: What is the mechanism of action of selective serotonin reuptake inhibitors (SSRIs)?
- Block serotonin reuptake at the presynaptic terminal (Correct answer)
- Increase serotonin synthesis
- Stimulate postsynaptic serotonin receptors directly
- Inhibit MAO enzymes
Correct answer: Block serotonin reuptake at the presynaptic terminal
SSRIs inhibit the serotonin transporter (SERT), preventing reuptake of serotonin into the presynaptic neuron, increasing serotonin availability in the synapse.
Question 2: According to NICE, which antidepressant class should be avoided in patients with a recent MI?
- Tricyclic antidepressants (TCAs) (Correct answer)
- SSRIs
- SNRIs
- Mirtazapine
Correct answer: Tricyclic antidepressants (TCAs)
TCAs have cardiotoxic effects including QT prolongation and arrhythmia risk, making them contraindicated post-MI. SSRIs are preferred for depression post-MI.
Question 3: Which proton pump inhibitor has the most significant interaction with clopidogrel?
- Omeprazole (Correct answer)
- Lansoprazole
- Pantoprazole
- Esomeprazole
Correct answer: Omeprazole
Omeprazole and esomeprazole are potent CYP2C19 inhibitors, reducing conversion of clopidogrel to its active metabolite. Pantoprazole has the least effect.
Question 4: What is serotonin syndrome and which combination most commonly causes it?
- Dangerous serotonergic excess; SSRI + tramadol (Correct answer)
- Antibiotic resistance; macrolide + SSRI
- Opioid toxicity; tramadol + morphine
- Hypertensive crisis; MAOI + paracetamol
Correct answer: Dangerous serotonergic excess; SSRI + tramadol
Serotonin syndrome is life-threatening excess serotonin activity causing hyperthermia, clonus, and agitation. SSRI combined with tramadol (also serotonergic) is a common precipitant.
Question 5: A patient is prescribed lithium. Which monitoring parameter is most critical?
- Serum lithium levels, renal function, and thyroid function (Correct answer)
- Blood glucose only
- Full blood count only
- Liver enzymes only
Correct answer: Serum lithium levels, renal function, and thyroid function
Lithium has a narrow therapeutic index. Regular monitoring of serum lithium (0.4–1.0 mmol/L), renal function (lithium is renally cleared), and thyroid function is essential.
Question 6: According to BNF, what is the first-line treatment for Helicobacter pylori eradication?
- Triple therapy: PPI + amoxicillin + clarithromycin for 7 days (Correct answer)
- PPI alone for 4 weeks
- Metronidazole monotherapy
- Bismuth quadruple therapy
Correct answer: Triple therapy: PPI + amoxicillin + clarithromycin for 7 days
UK first-line H. pylori eradication is triple therapy: a PPI + amoxicillin + clarithromycin for 7 days. Clarithromycin resistance affects choice in some areas.
GPhC Clinical Therapeutics & BNF Guidelines 3
What is the mechanism of action of selective serotonin reuptake inhibitors (SSRIs)?