Drugs Acting on ANS

Autonomic Nervous System (ANS)

Controls involuntary/visceral functions; regulates BP, HR, respiration, temperature, water balance, digestion, urinary excretion.

Main nerve centers of ANS

Hypothalamus, Medulla, Spinal Cord.

Divisions of ANS

Sympathetic Nervous System (SNS), Parasympathetic Nervous System (PNS).

General response of SNS

Fight or Flight: ↑ BP, HR, bronchodilation, pupil dilation, ↓ digestion/urination, glycogenolysis, suppressed immunity.

General response of PNS

Rest and Digest: ↑ GI motility and secretions, bladder emptying, bronchoconstriction, pupillary constriction, energy conservation.

Sympathetic neurotransmitters

Acetylcholine (preganglionic), norepinephrine/epinephrine (postganglionic).

Parasympathetic neurotransmitters

Acetylcholine (both pre- and postganglionic).

Adrenergic receptors

Alpha1, Alpha2, Beta1, Beta2.

Cholinergic receptors

Muscarinic, Nicotinic.

Adrenergic agonists (sympathomimetics)

Drugs that mimic SNS activity.

Alpha & Beta Adrenergic Agonists

Stimulate all adrenergic receptors → ↑ HR/contractility, bronchodilation, vasoconstriction (↑ BP), glycogenolysis.

Sample medications of Alpha & Beta Agonists

Dobutamine, Dopamine, Ephedrine, Epinephrine, Metaraminol, Norepinephrine.

Indications of Alpha & Beta Agonists

Shock, bronchospasm, asthma, cardiac arrest, hypotension.

Contraindications of Alpha & Beta Agonists

Pheochromocytoma, tachyarrhythmias, hypovolemia, halogenated anesthetics, hypersensitivity.

Adverse effects of Alpha & Beta Agonists

Arrhythmias, hypertension, angina, palpitations, nausea, constipation, headache, sweating.

Drug interactions of Alpha & Beta Agonists

↑ effects with TCAs, MAOIs; antagonized by adrenergic blockers.

Nursing considerations of Alpha & Beta Agonists

Monitor BP, HR, ECG, urine output; prevent extravasation (phentolamine antidote).

Alpha-Specific Adrenergic Agonists

Bind primarily to alpha receptors → vasoconstriction, ↑ BP, pupil dilation.

Sample medications of Alpha-Specific Agonists

Phenylephrine, Clonidine, Midodrine.

Indications of Alpha-Specific Agonists

Shock, hypotension, hypertension control, orthostatic hypotension, pain.

Contraindications of Alpha-Specific Agonists

Allergy, severe hypertension, tachycardia, narrow-angle glaucoma.

Adverse effects of Alpha-Specific Agonists

Anxiety, restlessness, CNS depression, arrhythmias, blurred vision, urinary difficulty.

Drug interactions of Alpha-Specific Agonists

Phenylephrine + MAOIs/TCAs → severe hypertension; Clonidine + TCAs → ↓ effect.

Nursing considerations of Alpha-Specific Agonists

Monitor BP, ECG, urine output; taper drug to avoid rebound hypertension.

Beta-Specific Adrenergic Agonists

Stimulate beta2 receptors → bronchodilation, uterine relaxation, ↑ HR/contractility.

Sample medications of Beta-Specific Agonists

Albuterol, Levalbuterol, Metaproterenol, Pirbuterol, Isoetharine, Isoproterenol.

Indications of Beta-Specific Agonists

Asthma, bronchospasm, COPD, shock, arrhythmias.

Contraindications of Beta-Specific Agonists

Allergy, pulmonary HTN, eclampsia, pregnancy, lactation.

Adverse effects of Beta-Specific Agonists

Restlessness, tremors, tachycardia, angina, MI, pulmonary edema, nausea.

Nursing considerations of Beta-Specific Agonists

Monitor respiratory status, HR, BP, ECG; have beta-blocker ready for overdose.

Adrenergic Blocking Agents

Sympatholytics → block SNS effects.

Nonselective Adrenergic Blocking Agents

Block both alpha & beta receptors → ↓ BP, HR, renin release.

Sample medications of Nonselective Adrenergic Blocking Agents

Carvedilol, Labetalol, Amiodarone.

Indications of Nonselective Adrenergic Blocking Agents

Hypertension, arrhythmias, heart failure, post-MI management.

Contraindications of Nonselective Adrenergic Blocking Agents

Bradycardia, heart block, asthma, shock, pregnancy, lactation.

Adverse effects

Dizziness, fatigue, hypotension, bronchospasm, GI upset, depression.

Drug interactions

↑ hypotension with anesthetics; hypoglycemia with antidiabetics.

Nursing considerations

Monitor BP, HR, ECG, respiratory status, glucose; taper slowly.

Nonselective Alpha Blockers

Phentolamine → blocks alpha1 & alpha2 receptors.

Indications for Nonselective Alpha Blockers

HTN in pheochromocytoma, diagnosis of pheochromocytoma, extravasation antidote.

Adverse effects of Nonselective Alpha Blockers

Hypotension, angina, tachycardia, flushing, dizziness.

Nursing considerations for Nonselective Alpha Blockers

Monitor BP closely, inject into extravasation site.

Alpha1-Selective Blockers

Block alpha1 receptors → vasodilation, ↓ BP, relaxation of bladder/prostate smooth muscle.

Indications for Alpha1-Selective Blockers

Hypertension, benign prostatic hypertrophy (BPH).

Adverse effects of Alpha1-Selective Blockers

Headache, dizziness, fatigue, arrhythmias, hypotension, edema.

Nursing considerations for Alpha1-Selective Blockers

Monitor BP, cardiac output, urinary function; provide safety measures.

Nonselective Beta Blockers

Block beta1 & beta2 receptors → ↓ HR, contractility, bronchoconstriction.

Sample medications for Nonselective Beta Blockers

Propranolol, Nadolol, Timolol.

Indications for Nonselective Beta Blockers

HTN, angina, arrhythmias, post-MI prevention.

Contraindications for Nonselective Beta Blockers

Asthma, COPD, bradycardia, heart block.

Adverse effects of Nonselective Beta Blockers

Bradycardia, hypotension, bronchospasm, fatigue, impotence.

Drug interactions for Nonselective Beta Blockers

↓ antihypertensive effect with NSAIDs; paradoxical HTN with clonidine.

Nursing considerations for Nonselective Beta Blockers

Monitor BP, HR, respiratory status; taper slowly.

Beta1-Selective Blockers

Selective to heart → ↓ HR, contractility, workload.

Sample medications for Beta1-Selective Blockers

Atenolol, Metoprolol, Esmolol, Bisoprolol.

Indications for Beta1-Selective Blockers

HTN, angina, arrhythmias, post-MI, glaucoma.

Adverse effects of Beta1-Selective Blockers

Bradycardia, hypotension, fatigue, dizziness, GI upset.

Drug interactions for Beta1-Selective Blockers

↑ effects with cimetidine, verapamil; ↓ effect with NSAIDs, rifampin.

Nursing considerations for Beta1-Selective Blockers

Monitor HR, BP, ECG; taper drug before discontinuation; give metoprolol with food.

Cholinergic Agonists (Parasympathomimetics)

Mimic PNS activity → muscarinic/nicotinic stimulation.

Direct-Acting Cholinergics

Bind to ACh receptors → ↑ bladder tone, GI secretions, pupil constriction.

Sample medications for Direct-Acting Cholinergics

Bethanechol, Carbachol, Pilocarpine, Cevimeline.

Indications for Direct-Acting Cholinergics

Post-op urinary retention, glaucoma, Sjögren syndrome.

Adverse effects of Direct-Acting Cholinergics

Bradycardia, hypotension, diarrhea, ↑ salivation, urinary urgency, sweating.

Nursing considerations for Direct-Acting Cholinergics

Monitor HR, BP, urine output; antidote = Atropine.

Indirect-Acting Cholinergics

Inhibit acetylcholinesterase → ↑ ACh at receptors.

Sample medications for Indirect-Acting Cholinergics (Myasthenia Gravis)

Neostigmine, Pyridostigmine, Ambenonium, Edrophonium.

Sample medications for Indirect-Acting Cholinergics (Alzheimer's)

Donepezil, Rivastigmine, Galantamine, Tacrine.

Indications for Indirect-Acting Cholinergics

Myasthenia gravis, Alzheimer's disease, antidote for NMJ blockers, nerve gas exposure.

Adverse effects of Indirect-Acting Cholinergics

Bradycardia, hypotension, diarrhea, urinary urgency, blurred vision, dizziness.

Drug interactions for Indirect-Acting Cholinergics

↑ GI bleeding with NSAIDs; ↑ theophylline toxicity with tacrine.

Nursing considerations for Indirect-Acting Cholinergics

Keep Atropine available; monitor ADLs, HR, BP, bowel & bladder function.

Anticholinergic Agents (Parasympatholytics)

Block muscarinic ACh receptors → inhibit PNS effects.

Sample medications for Anticholinergic Agents

Atropine, Scopolamine, Ipratropium, Tiotropium, Dicyclomine, Hyoscyamine, Glycopyrrolate.

Indications for Anticholinergic Agents

Decrease secretions, treat bradycardia, restore BP after vagal stimulation, GI/urinary relaxation, motion sickness, antidote for cholinergics.

Contraindications for Anticholinergic Agents

Glaucoma, GI obstruction, BPH, tachyarrhythmias, myasthenia gravis.

Adverse effects of Anticholinergic Agents

Dry mouth, blurred vision, constipation, urinary retention, tachycardia, photophobia, CNS confusion.

Drug interactions for Anticholinergic Agents

↑ anticholinergic effects with antihistamines, MAOIs, TCAs; ↓ phenothiazine effect.

Nursing considerations for Anticholinergic Agents

Encourage fluids, oral care, monitor HR, BP, urinary output; safety measures; avoid heat exposure.