This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Osteoporosis, Sex Hormones and OCPs, Subject name: Pharmacology
Which of the following drug is implicated in the causation of osteomalacia of the bone? 
Select and explain. 
A. Phenytoin, B. Steroids, C. Heparin, D. Estrogen
A: Phenytoin
Answer: A: Phenytoin 
Explanation: Phenytoin inhibit the hepatic production of 25 hydroxy vitamin D and also directly inhibit bone mineralization and thus may result in osteomalacia. Steroids and heparin result in osteoporosis not osteomalacia. Impoant drugs causing osteomalacia are: Phenytoi Carbamazepine Valproate Phenobarbitone Bisphosphonates