S15C191 - Anticonvulsants

Question 1

Phenytoin: pharmaco

Answer 1

• anticonvulsant, antidysrhythmic (dig tox)

- Na channel blocker

Question 2

Phenytoin: OD

Answer 2

• CVS: brady, HoTN, asystole (usually from IV dilantin, not PO), VT/VF, long PR, wide QRS
• tissue necrosis
• early toxicity: nystagmus, dysdiadochokinesia, ataxia
• confusion, dizzy, loss of concn, memory
• rarely: Sz
• PO OD: nystagmus, n/v, ataxia, dysarthria, choreoatehtosis, opisthotonos, neuro depn/excitation
• SJS
• NB: diluents of phenytoin include propylene glycol and ethanol

Question 3

Phenytoin: OD Tx

Answer 3

• ABCD
• HD
• pacing

Question 4

Carbamazepine OD

Answer 4

• Na channel blocker and interferes with muscarinic/nicotinic R’s and NMDA R’s
• anticholinergic, antiarrhythmic, antidepressant, sedative, and neuromuscular blocking, antidiuretic
• Sx: coma, resp failure, ataxia, nystagmus, ileus, hypertonicity, incr DTR, dystonic rxn, anticholinergic Sx
• wide QRS, Sz, hyponatremia, hyperglycemia
• Tx: ABCD
• HD
• NaHCO3- if conduction delay on ECG

Question 5

Valproate OD

Answer 5

-increases GABA, decreases GHB blocks NMDA

• Sx: CNS dpn, resp dpn, HoTN, hypoglycemia, hypocalcemia, hypernatremia, hypophosphatemia, AGMA, hyperammonemia
• symptoms occur at leveles >150mcg/ml and coma at 800mcg/ml
• tx: ABCD
• naloxone for CNS dpn
• E = HD
• F = L-carnitine for lethargy, coma, hyperammonemia, hepatic dysfxn

Question 6

Lamotrigine

Answer 6

• wide QRS, long QT, pancreatitis, Sz, status, coma
• give NaHCO3- for wide QRS and MgSo4 for long QT
• lipid emulsion