Question
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- (a) Enumerate four Selective Serotonin reuptake inhibitors. Write four uses and four adverse effects. ( 4 mark(s)
- (b) Briefly describe Lignocaine 4 mark(s)
Answer
a) Four SSRIs, uses, adverse effects Examples: Fluoxetine, Sertraline, Paroxetine, Escitalopram.
Uses: major depressive disorder (first-line), obsessive-compulsive disorder, panic disorder, generalized anxiety disorder/other anxiety disorders.
Adverse effects: nausea/GI disturbance, sexual dysfunction, insomnia or somnolence (varies by agent), serotonin syndrome risk with other serotonergic drugs/MAOIs.
b) Lignocaine Lignocaine (Lidocaine) is an amide local anesthetic, metabolized hepatically (slower than ester hydrolysis, longer duration, and genuinely rare true allergy compared to esters).
Mechanism: blocks voltage-gated Na⁺ channels from the intracellular side of the neuronal membrane, preventing the Na⁺ influx that generates the action potential’s rising phase, producing reversible loss of sensation.
Uses: local/regional anesthesia (infiltration, nerve block, epidural, topical — e.g. EMLA cream with prilocaine), and as a Class IB antiarrhythmic (IV, for ventricular arrhythmias, particularly post-MI) via the same Na⁺-channel blocking mechanism.
Adverse effects: CNS toxicity at high plasma levels (perioral numbness, tinnitus, progressing to seizures), cardiovascular depression/arrhythmia at very high levels — reflecting the same Na⁺-channel mechanism extending systemically; often combined with adrenaline to prolong local action and reduce systemic absorption.