Fluoroquinolones are antibacterials that

Correct Answer: C

Rationale: Rationale for Correct Answer C: Fluoroquinolones interfere with metabolic processes by targeting bacterial enzymes involved in DNA replication and repair. This disrupts bacterial DNA synthesis, leading to cell death. This mechanism is distinct from options A, B, and D, which target different cellular components such as the cell wall, membrane, and protein synthesis. Hence, C is the correct choice for fluoroquinolones.

Correct Answer: D

Rationale: First pass metabolism refers to the metabolism of a drug in the liver before it reaches systemic circulation. This process greatly reduces the fraction of unchanged drug that reaches systemic circulation, as the drug may be metabolized or broken down before it can exert its effects. This leads to lower bioavailability of the drug. Choice A is incorrect because first pass metabolism does affect the fraction of unchanged drug reaching systemic circulation. Choice B is incorrect as first pass metabolism does not necessarily impact the half-life of the drug in plasma. Choice C is incorrect because first pass metabolism does not accelerate the absorption rate of the drug; instead, it may decrease it by metabolizing the drug before it can be absorbed.

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: D

Rationale: The correct answer is D, Cetirizine hydrochloride. Cetirizine is an antihistamine used to treat allergies and does not have any effect on reducing gastric acid production. Aluminium hydroxide (A) is an antacid that neutralizes stomach acid. Cimetidine (B) is an H2 blocker that reduces acid production. Omeprazole (C) is a proton pump inhibitor that also decreases stomach acid production. Therefore, D is the correct answer as it does not have any impact on gastric acid levels.

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.