Neurologic Medications

Seizures, Parkinson's, myasthenia gravis and dementia

Pharmacology

Antiseizure medications

Phenytoin	Level 10–20 mcg/mL. Gum overgrowth (oral hygiene), ataxia, nystagmus (toxicity), rash. IV: saline only, max 50 mg/min, in-line filter; extravasation injury. Many interactions. Fosphenytoin is safer IV
Levetiracetam	Few interactions; mood changes, irritability
Valproate	Liver, pancreas, platelets; birth defects
Carbamazepine	Low sodium, low blood counts, SJS; induces enzymes (weakens birth control)
Lamotrigine	Rash/SJS: slow dose increases

Teach: don't stop suddenly (seizures); medical ID; no driving until cleared; folic acid before pregnancy. Status epilepticus: IV lorazepam (or IM midazolam) first, then a second-line IV drug (levetiracetam, fosphenytoin, valproate).

Parkinson's disease

Carbidopa-levodopa: most effective. Nausea, orthostatic hypotension, dyskinesias, "wearing-off". High-protein meals reduce absorption: spread protein through the day. Dark urine and sweat. Never stop suddenly (NMS-like reaction).
Dopamine agonists (pramipexole, ropinirole): sleep attacks, impulse-control problems (gambling, shopping).
MAO-B inhibitors (selegiline, rasagiline); amantadine; anticholinergics (avoid in older adults).
Avoid: metoclopramide, haloperidol (worsen symptoms).

Myasthenia gravis

Pyridostigmine: take on time, 30–60 min before meals (helps chewing and swallowing).
Myasthenic crisis (too little drug or illness) vs. cholinergic crisis (too much: SLUDGE, bradycardia, small pupils). Both cause weakness and respiratory failure: airway first; atropine for cholinergic crisis.
Newer: complement inhibitors and FcRn blockers (e.g., efgartigimod).
Avoid drugs that worsen MG: aminoglycosides, fluoroquinolones, magnesium, some beta blockers.

Alzheimer's disease

Cholinesterase inhibitors (donepezil, rivastigmine patch, galantamine): nausea, bradycardia, syncope; donepezil at bedtime (vivid dreams → morning).
Memantine: moderate–severe disease; dizziness.
Anti-amyloid antibodies for early disease: donanemab (IV every 4 weeks), lecanemab (IV, or weekly subcutaneous autoinjector). MRI monitoring for ARIA (brain swelling or bleeding): headache, confusion, vision change. APOE ε4 carriers are at higher risk. New

Memory hook: cholinergic excess = SLUDGE Salivation · Lacrimation · Urination · Defecation · GI upset · Emesis. Plus bradycardia, bronchospasm, small pupils. Opposite of the anticholinergic "can't see, can't pee" picture.