Autonomics

  • Cholinomimetic agents
  • Direct Agonists
    • Bethanechol
    • Used to treat urinary retention or atonic bladder
    • Carbachol
    • Methacholine
    • Pilocarpine
  • Indirect Agonists (Anticholinesterases, Acetylcholinesterase Inhibitors)
    • Donepezil
    • 5mg qhs, max 10mg
    • Metabolized by 2D6 and 3A4
    • Cirrhosis reduces clearance by 20%
    • Less GI SE
    • Edrophonium
    • Neostigmine
    • Physostigmine
    • Pyridostigmine
    • Rivastigmine
    • 1.5mg BID up to 3mg BID, patch
    • SE: More GI and Cardiac SE due to PNS and CNS effects
  • Muscarinic Antagonists (Antimuscarinics)
    • General
    • May trigger angle closure glaucoma/mydriasis
    • Anticholinergic effects, decrease acetylcholine activity
    • Useful for treating tremor and rigidity
    • Not useful for treating bradykinesia
    • Atropine
    • Benztropine (Cogentin)
    • Trihexyphenidyl
    • Glycopyrrolate
    • Hycosamine
    • Imipramine
    • Antidepressant used to treat childhood enuresis, promotes urinary retention
    • Ipratropium
    • Oxybutynin
    • Inhibits cholinergic input during bladder filling
    • Helps improve bladder capacity and is used to treat overactive bladder (detrusor instability)
    • Scopolamine
  • Sympathomimetic agents
  • Direct Sympathomimetics
    • Albuterol
    • Dobutamine
    • B1 ≥ B2/A1
    • Increases myocardial contractility in decompensated HF
    • Improved EF and reduced LV ESV reducing edema
    • B1 stimulation (inotropic)
    • Mild B2 stimulation (vasodilator)
    • Increase O2 consumption bad for MI or failing MI
    • Dopamine
    • Epinephrine
    • Alpha and Beta adrenergic
    • Leads to venoconstriction, arterioconstriction, and increased contractility to increase preload, afterload, and CO
    • Fenoldopam
    • CI: glaucoma or increased intracerebral pressure
    • Isoproterenol
    • Midodrine
    • Norepinephrine
    • Phenylephrine
  • Indirect Sympathomimetics
    • Amphetamine
    • Cocaine
    • Ephedrine
  • Sympatholytic (alpha-2 agonists)
    • Clonidine (Catapres)
    • Central alpha 2 agonist, reduces NE release
      • Increases gut salt and water uptake
    • Efficacy in treating autonomic neuropathy caused diarrhea in diabetics
    • Can reduce cravings in narcotic and alcohol withdrawal, smoking cessation
    • Taper by decreasing dose by 50% over 3 days
    • SE: Hypertensive crisis, Hypotension, bradycardia
    • Guanfacine
    • Tizanidine
    • Alpha-Methyldopa

  • Alpha-blockers

    • Nonselective alpha blockers
    • Phenoxybenzamine
    • Phentolamine
      • Useful in patients with pheochromocytoma, cocaine toxicity, amphetamine overdose, clonidine withdrawal
    • Alpha-1 antagonists
    • Prazosin

    • Terazosin

    • Doxazosin (Cardura)

    • Tamsulosin

      • Relaxes ureteral muscle and decreases intraureteral pressure
    • Trazodone
    • Alpha-2 antagonists
    • Mirtazapine (Remeron)