Drug Therapy

Step 1: Understanding drug placental crossing.
Heparin, unlike Warfarin, does not cross the placenta. This is why it is preferred for use in pregnant women for conditions like deep vein thrombosis, as it does not pose a risk to the fetus.
Step 2: Analyzing the options.
(1) Warfarin: Incorrect, Warfarin does cross the placenta and can cause harm to the developing fetus.
(2) Heparin: Correct — Heparin does not cross the placenta, making it safe for use during pregnancy.
(3) Phenindione: Incorrect, Phenindione crosses the placenta and has similar risks to Warfarin.
(4) Bromocriptine: Incorrect, Bromocriptine can cross the placenta.
Step 3: Conclusion.
The correct answer is (2) Heparin.

Step 1: Understanding 5-fluorouracil absorption.
5-fluorouracil, a chemotherapeutic agent, is absorbed primarily via passive diffusion, which occurs due to its lipophilic properties and concentration gradient across cell membranes.
Step 2: Analyzing the options.
(1) Passive diffusion: Correct — Passive diffusion is the most common mechanism for absorption of 5-fluorouracil.
(2) Active transport: Incorrect, 5-fluorouracil does not require energy or a carrier for absorption.
(3) Pinocytosis: Incorrect, this is not a typical mechanism for absorption of 5-fluorouracil.
(4) Ion pair absorption: Incorrect, 5-fluorouracil does not rely on ion pair absorption.
Step 3: Conclusion.
5-fluorouracil is absorbed by (1) Passive diffusion.

Step 1: Understanding teratogenicity.
Teratogenicity refers to the ability of a substance to cause birth defects in a developing fetus. Chloramphenicol is known to be teratogenic and should be avoided during pregnancy.
Step 2: Analyzing the options.
(1) Chloramphenicol: Correct — Chloramphenicol is known to be teratogenic and can cause fetal harm.
(2) Aspirin: Incorrect, while aspirin can cause some risks during pregnancy, it is not typically teratogenic.
(3) Paracetamol: Incorrect, Paracetamol is generally considered safe for use during pregnancy and is not teratogenic.
(4) Cetirizine: Incorrect, Cetirizine is an antihistamine that is not associated with teratogenic effects.
Step 3: Conclusion.
The correct answer is (1) Chloramphenicol.