Medications that can reduce serum vitamin D levels include which of the following?

• A. Rifampicin, Phenytoin
• B. Fluoxetine, Sertraline
• C. Amiodarone, Digoxin
• D. Ibuprofen, Paracetamol

Answer: (A)

Medications that reduce serum vitamin D levels are those that induce hepatic enzymes, speeding up the breakdown of vitamin D and its metabolites. Rifampicin and phenytoin are classic examples of this inducers group. By ramping up hepatic cytochrome P450 activity, they increase the metabolism of 25-hydroxyvitamin D and its active forms, leading to lower circulating vitamin D and a higher risk of bone problems such as osteomalacia with long-term use.

The other drugs listed don’t have this effect: SSRIs like fluoxetine and sertraline don’t meaningfully alter vitamin D metabolism; amiodarone and digoxin affect cardiac or thyroid/liver function in different ways but aren’t known to decrease vitamin D levels; and NSAIDs or acetaminophen don’t impact vitamin D metabolism.