CLASSIFICATIONS Of DRUGS

DRUGS AFFECTING THE CENTRAL AND AUTONOMIC SYSTEM

Cholinergic Agents (Parasympathomemitics)
Prototype :
- synthetic acetylcholine, pilocarpine, carbachol, bethanecol (Urocholine),
edrophonium (Tensilon), neostigmine (Prostigmine), pyridostigmine (Mestinon).
Mechanism of action :
- stimulates cholinergic receptors by mimicking acetylcholine or inhibition of
enzyme cholinesterase.
Indications :
- glaucoma, urine retention, Myasthenia Gravis
- antidote to neuromuscular blocking agents : tricyclic antidepressants and atropine
Adverse effects :
- blurring of vision, miosis
- increase in salivation, intestinal cramps
- bronchoconstriction, wheezing, DOB
- hypotension and bradycardia
Nursing considerations :
1. Warn & monitor clients of the side effects.
2. Have atropine available for use as antidote.



Cholinergic Blocking Agents (Parasympatholytics, Anticholinergics)
Prototype :
- atropine, scopalamine (Triptone), dicyclomine (Bentyl),
propantheline (Pro-Banthine).
Mechanism of actions :
- block the binding of acetylcholine in the receptors of parasympathetic nerves.
Indications :
- use preoperatively to dry up secretions.
- treat spasticity of GI or urinary tract.
- use for treatment of bradycardia, asthma, parkinsonism.
- use for antidote in organophosphate poisoning.
Adverse effects :
- dry mouth , dilatation of pupils, tachycardia
- urinary retention, ileus, heat stroke
Nursing considerations :
1. Keep client’s in cool environment.
2. Watch out for signs of heatstroke and dehydration.
3. Encourage clients to increase fluid intake and use of sugarless gum/candy for dry
mouth.
4. For GI spasticity, administer 30 minutes before meals and at bed time.

Adrenergic Agents (Sympathomimetics)
Prototype :
- epinephrine, norepinephrine, ephedrine, dopamine, dobutamine, phenylephrine,
terbutaline, albuterol, isoproterenol.
Mechanism of actions :
- stimulate alpha and beta adrenergic receptor directly or trigger the release of
catecholamines indirectly causing sympathetic effects.
Indications :
- cardiopulmonary arrest, hypotension
- COPD and asthma, nasal congestions
- allergic reaction, anaphylactic shock
Adverse effects :
- restlessness, insomnia, tremors, nausea
- palpitations, angina, tachycardia, HPN
Nursing considerations :
1. Contraindicated in clients w/ hyperthyroidism,
pheochromocytoma & cardiovascular disease.
2. Monitor vital signs and advice precautions.
3. Should be taken with food.




Adrenergic Blocking Agents
Prototype :
a. Alpha blockers
- phentolamine (Regintine), phenoxybenzamine, prazosin (Minipress),
reserpine (Serpasil), terazosin (Hytrin)
- clonidine (Catapress), methyldopa (Aldomet)
b. Beta blockers
- atenolol (Tenormin), esmolol (Brevibloc),
metoprolol (Lopressor), nadolol (Corgard),
propanolol (Inderal), timolol ( Blocadren)
Mechanism of actions :
a. alpha blockers
- inhibits action of a-receptors in vascular smooth muscle to cause vasodilatation.
b. beta blockers
- compete with epinephrine in b-receptors in heart, pulmonary airways, peripheral
circulation and CNS.
Indications :
- Raynaud’s disease, hypertension, pheochromocytoma.
- angina, arrhythmias, mitral valve prolapse, glaucoma
Adverse effects :
- orthostatic hypotension, bradycardia, CHF


- depression, insomnia and vertigo
- bronchospasm and dyspnea, nasal stuffiness, cold extremities

Nursing considerations :
1. Administer oral alpha-blockers with milk to minimize GI side effects.
2. Administer oral beta-blockers before meals and at a.m. if insomnia occurs.
3. Check client’s apical pulse rate before drug administration, refer if below 60 bpm.
4. Hypotensive precautions.
5. Warn clients not to drive or operate dangerous machinery until he/she has
adjusted to medications