This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Epilepsy, Subject name: Pharmacology
Selective decrease in IgA is seen with administration of: 
Select and explain. 
A. Phenytoin, B. Diazepam, C. Clonazepam, D. Phenobarbitone
A: Phenytoin
Answer: A: Phenytoin 
Explanation: Ans: A (Phenytoin) Ref: Goodman & Gillman's The Pharmacological Basis of Therapeutics, 2011, 12th Edition, McGrow Hid, Burton LL, P 593Explanation:Phenytoin can cause lymphadenopathv similar to Hodgkin's disease and malignant lymphoma. This is attributed to decrease in IgA production.Other Adverse Effects of PhenytoinNeurologicHorizontal gaze nystagmusSedationCerebellar ataxiaCerebellar atrophyOphthalmoparesisSeizuresHematologicMegaloblastic anemiaAgranulocytosisAplastic anemiaLeukopenia Thrombocytopenia.TeratogenicityPhenytoin is a known teratogen and causes "fetal hydantoin syndrome"The syndrome consists of craniofacial anomalies \ broad nasal bridge, cleft lip and palate, microcephaly) and a mild form of mental retardation (average IQ=71)DermatologicHypertrichosisRashExfoliative dermatitisPruritisHirsutismCoarsening of facial featuresSJS and TENOthersGingival hypertrophy (overgrowth of the gums) (can be decreased with folate supplementation)Induction of reversible IgA deficiencyDrug-induced lupus.Hypocalcemia