Which of the following adverse effects is most likely to occur during the first days of lithium therapy?

Correct Answer: C

Rationale: Insomnia is a common early adverse effect of lithium therapy due to its impact on sleep patterns. Patients may experience difficulty falling asleep or staying asleep during the initial days of treatment. This side effect typically resolves as the body adjusts to the medication. Constipation, weight loss, hypertension, and edema are less commonly associated with lithium therapy in the early stages.

Correct Answer: D

Rationale: MAO inhibitors can increase dopamine levels excessively when combined with levodopa, leading to hypertensive crises.

Correct Answer: C

Rationale: Ethanol competes with methanol for alcohol dehydrogenase preventing the formation of toxic metabolites.

Correct Answer: D

Rationale: Donepezil, a cholinesterase inhibitor, increases synaptic acetylcholine levels by preventing its breakdown, improving cognitive function in Alzheimer's disease.

Correct Answer: D

Rationale: Ketamine can increase heart rate and is contraindicated in conditions like sick sinus syndrome.