This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
Which of the following sulphonamides is available as an oral preparation? 
Select and explain. 
A. Sulphacetamide, B. Sulphadiazine, C. Silver sulphadiazine, D. Mafenide
B: Sulphadiazine
Answer: B: Sulphadiazine 
Explanation: Sulfadiazine is a sulfonamide which can used orally, as it is rapidly absorbed & rapidly excreted. It is 50% plasma protein bound & 20-40% acetylated. It has good penetration in CSF & brain, therefore used in the treatment of meningitis. Ref: Essentials of Medical Pharmacology, 5th Edition, Pages 641-3