Which of the following is NOT a monoamine neurotransmitter?

Correct Answer: A

Rationale: The correct answer is A: Serotonin (5-HT) is NOT a monoamine neurotransmitter. Monoamine neurotransmitters have a single amino group and are derived from amino acids like tyrosine. Serotonin, however, is derived from tryptophan and belongs to the indoleamine class. Dopamine, Noradrenaline, and Adrenaline are all monoamine neurotransmitters derived from tyrosine and phenylalanine. Therefore, Serotonin does not fit the criteria for being a monoamine neurotransmitter, making choice A the correct answer.

Correct Answer: A

Rationale: First-pass metabolism occurs when drugs are absorbed from the gastrointestinal tract and pass through the liver before reaching the systemic circulation. The oral route is affected by first-pass metabolism as drugs are metabolized in the liver before entering the bloodstream. Sublingual bypasses the liver due to absorption through the oral mucosa. Intravenous administration delivers drugs directly into the bloodstream, avoiding first-pass metabolism. Rectal administration partially bypasses the liver, but some drug metabolism can still occur. Therefore, the correct answer is A (Oral), as it is affected by first-pass metabolism.

Correct Answer: C

Rationale: Increased binding of drugs to plasma proteins leads to a decrease in the concentration of free drug available for elimination. This results in a longer half-life of the drug as it takes longer for the bound drug to be released and metabolized. This does not directly impact drug-drug interactions or renal filtration, as binding to plasma proteins affects the distribution and elimination of the drug. Therefore, the correct answer is C.

Correct Answer: A

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.

Correct Answer: B

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.