Which of the following drugs most likely caused the patient’s symptoms and signs?
A 44-year-old man complained to his physician of burning and tickling in his hands and
feet. The man has diagnosed with tonic-clonic seizures three years ago and has been
receiving a high dose of an antiseizure drug since then. Physical examination disclosed
large inguinal lymph nodes and reflex testing showed lack of knee and ankle tendon
reflexes. Further lab exams showed megaloblastic anemia.
A. Gabapentin B. Lamotigrine C. Clonazepam D. Phenytoin E. Levetiracetam F. Tiagabine
the symptom and signs of the patient indicated that ha was most likely suffering from peripheral
neuropathy and lymphadenopathy which are adverse effect of long-term use of phenytoin.
megaloblastic anemia is an adverse effect of long lasting treatment with phenytoin. the drug
inhibits the enzyme conjugase, located in the brush border of the intestinal mucosa, which
hydrolyzes the glutamate residues of ingested polyglutamates, so allowing the absorption of
monoglutamates. patients under high doses of phenytoin drug can show megaloblastic anemia,
lymphoid hyperplasia and paresthesias. knee and ankle tendon reflexes are absent in about
18% of these patients.
a, b, c, e, f) all these drugs do not show the combination of the above mentioned adverse