Pharm - Unit 2 - Chapter 20-21 - Cholinergic Drugs/Cholinergic Blocking Drugs

Key terms and prototypes

Acetylcholine

The neurotransmitter responsible for the transmission of nerve impulses to effector cells in the parasympathetic nervous system.

Acetylcholinesterase

The enzyme responsible for the breakdown of acetylcholine.

Parasympathomimetics

Drugs that mimic the parasympathetic nervous system - also referred to as cholinergic agonist drugs.

Bethanechol (Urecholine)

Mechanism of Action: (Direct-acting drug) Stimulates the parasympathetic nervous system

Indications: increased bladder and GI tract tone and motility

Routes: Oral

Adverse effects: Syncope (fainting), hypotension, reflex tachycardia, hypertension, bradycardia

Contraindications: Drug allergy, gastrointestinal or genitourinary obstruction 

Toxicity: Cholinergic crisis (muscle weakness, respiratory paralysis), circulatory collapse, hypotension

Interactions: Anticholinergics and antihistamines may antagonize.

Donepezil (Aricept)

Mechanism of Action: (Indirect-acting drug) Stimulates the parasympathetic nervous system

Indications: Cause skeletal muscle contraction, increases acetylcholine in the brain

Routes: Oral

Adverse effects: Syncope (fainting), hypotension, reflex tachycardia, hypertension, bradycardia

Contraindications: Drug allergy, gastrointestinal or genitourinary obstruction 

Toxicity: Cholinergic crisis (muscle weakness, respiratory paralysis), circulatory collapse, hypotension

Interactions: Anticholinergics and antihistamines may antagonize.

Parasympatholytics

Drugs that reduce the activity of the parasympathetic nervous system; also called anticholinergics.

Atropine

Mechanism of Action: Cholinergic-blocking drug - blocks the action of the neurotransmitter acetylcholine at the muscarinic receptors in the parasympathetic nervous system (PNS). More potent than scopolamine.

Indications: bradycardia, ventricular asystole

Routes: IV, oral, ophthalmic

Adverse effects: increased heart rate, restlessness, drowsiness, dilated pupils, decreased salivation, urinary retention

Contraindications: angle-closure glaucoma, advanced hepatic and renal dysfunction, acute asthma or other respiratory distress

Toxicity: 

Interactions: Additive effects with other anti-cholinergic drugs

Scopolamine

Mechanism of Action: Cholinergic-blocking drug - blocks the action of the neurotransmitter acetylcholine at the muscarinic receptors in the parasympathetic nervous system (PNS).

Indications: motion sickness

Routes: transdermal

Adverse effects: increased heart rate, restlessness, drowsiness, dilated pupils, decreased salivation, urinary retention

Contraindications: Drug allergy, angle-closure glaucoma, advanced hepatic and renal dysfunction, acute asthma or other respiratory distress

Toxicity: 

Interactions: Additive effects with other anti-cholinergic drugs