drugs affecting the_parasympathetic_nervous_system

Drugs Affecting the Parasympathetic Nervous System

Nelia B. Perez RN, MSN

1. It is the main neurotransmitter in the PNS.a. MAOb. Achc. ACTHd. ADH

2. This is the alkaloid substance found in tobacco.a. Caffeineb. Sugarc. Tard. Nicotine

3. Found at the parasympathetic postganglionic nerve endings and acts like Ach.a. Nicotinic Receptorsb. Ganglionic receptorsc. Muscarinic receptorsd. Sympathetic receptors

4. They produces ACH like effect and slowly inactivated by acetylcholinesterase.a. Direct Acting Cholinergic Drugs

b. Muscarinic drugs c. Adrenergic drugs d. Indirect acting cholinergic drugs

• .

• .

5. It blocks cholinergic and nicotinic receptors.

a.Reversible Inhibitorsb.Irreversible inhibitorsc.Cholinesterased.anticholinesterase

6. These are derivatives of organophosphate compounds which is widely used as insecticides, pesticides and chemical warfare agents. a. Cholinesteraseb. Reversible Inhibitorsc. Irreversible Inhibitorsd. None of these

7. A situation where there is excessive drug dosage in patients with myasthenia gravis and a high concentration of ACH causes excessive stimulation of the muscarinic receptors.a. Cholinergic Crisisb. hypertensive crisisc. Stroked. None of these

8. It binds to muscarinic receptors and act by competitive antagonism of ACH.a. Cholinergic drugsb. Cholinesterasec. anticholinesterased. Anticholinergic Drugs

9. It is the opposing system of the SNSa. ANSb. PNSc. CNSd. CVS

10.Major effects of the Cholinergic drugs.a. STONESb. DUALSc. SLUDGEd. SMUDGE

Drugs Affecting the Parasympathetic Nervous System

Parasympathetic Nervous System

• Neurotransmitter is ACH

• The receptors are called cholinergic receptors.

• Drugs that bind to cholinergic receptors and produced effects similar to ACH are referred to as cholinergic drugs.

Drugs Affecting the Parasympathetic Nervous System

ACHACH

ACH

ACH

ACH

ACH ACH

ACH

ACH

ACH

ACH

ACH

ACH

ACH

Acetylcholinesterase

Drugs Affecting the Parasympathetic Nervous System

Nicotinic ReceptorsMuscarinic Receptors

Receptors

N-1 N-2

Drugs Affecting the Parasympathetic Nervous System

Nicotinic Receptors

Nicotinic-II Receptors

Found at ganglions of Sympathetic and Parasympathetic Post- ganglionic fibers

Found at Neuromuscular junction ofSkeletal muscles.

Nicotinic-I Receptors

Parasympathetic Fibers

Post-ganglionic Fiber

Sympathetic Fibers

Pre-ganglionic Fiber

Pre-ganglionic Fiber

Post-ganglionic FiberAdrenergic Receptor

Muscarinic Receptors

Drugs Affecting the Parasympathetic Nervous System

Nicotinic II Receptors

Ganglion, Nicotinic I receptor

Ganglion, Nicotinic I receptor

Somatic Fibers

Drugs Affecting the Parasympathetic Nervous System

Nicotine

• Alkaloid obtained from tobacco.

• Stimulate the NI receptors at low doses.

• Block the NII receptors at high doses.

Drugs Affecting the Parasympathetic Nervous System

GanglionicBlockers

GanglionicStimulants

Nicotinic I Drugs

Drugs Affecting the Parasympathetic Nervous System

Muscarinic Receptors

• Found at the parasympathetic postganglionic nerve endings

• Drugs that act like ACH at these receptors are referred to as cholinergic or muscarinic drugs.

• Drugs that block ACH at the muscarinic receptors are referred to as anticholinergic or antimuscarinic drugs.

Drugs Affecting the Parasympathetic Nervous System

Anti-cholinergicDrugs

CholinergicDrugs

ParasympatheticDrugs

Drugs Affecting the Parasympathetic Nervous System

Direct ActingCholinergic Drugs

CholinergicDrugs

Indirect ActingCholinergic Drugs

Drugs Affecting the Parasympathetic Nervous System

Direct Acting Cholinergic Drugs

• Bind to muscarinic receptors.

• Produces ACH like effect.

• Slowly inactivated by acetylcholinesterase.

Cholinergic Drugs Drugs that stimulate the

parasympathetic nervous system (PSNS) opposing system to the SNS Known as: cholinergic agonists or

parasympathomimetics Mimic the effects of the PSNS neurotransmitter:

acetylcholine (Ach)

Cholinergic Drugs“rest and digest” system

“SLUDGE”

Salivation Lacrimation Urinary incontinence Diarrhea Gastrointestinal cramps Emesis

Cholinergic DrugsDrug Effects

Stimulate intestine and bladder Increased gastric secretions Increased gastrointestinal motility Increased urinary frequency

Stimulate pupils Constriction (miosis) Reduced intraocular pressure

Increased salivation and sweating Cardiovascular effects

Decreased heart rate Vasodilation

Respiratory effects Bronchial constriction, narrowed airways

Drugs Affecting the Parasympathetic Nervous System

Pharmocological Effects

• Increase GI secretion and motility

• Increase in genitourinary activity.

• Bronchoconstriction

Drugs Affecting the Parasympathetic Nervous System

Pharmocological Effects

• Miosis

• Vasodilatation (lower BP)

• Decrease heart rate.

Direct Acting Main Use

Acetylcholine Miotic

Bethanecol Nonobstructive urinary retention

Carbachol Treatment of glaucoma

Methacholine Miotic

Pilocarpine Treatment of glaucoma

Drugs Affecting the Parasympathetic Nervous System

Drugs Affecting the Parasympathetic Nervous System

IrreversibleInhibitors

ReversibleInhibitors

Indirect ActingCholinergic Drugs

(Anticholinesterases)

Drugs Affecting the Parasympathetic Nervous System

ACHACH

ACH

ACH

ACH

ACHACH

ACH

ACH

ACH

ACH

ACH

ACH

ACH

Acetylcholinesterase

Anticholinesterases

Drugs Affecting the Parasympathetic Nervous System

Reversible Inhibitors

• Blocks cholinergic and nicotinic receptors.

• Use in the diagnosis and treatment of myasthenia gravis.

Drugs Affecting the Parasympathetic Nervous System

Irreversible Inhibitors

• Derivatives of organophosphate compounds.

• Widely used as insecticides, pesticides and chemical warfare agents.

• Long duration of action

Drugs Affecting the Parasympathetic Nervous System

Clinical Use

• Topical use in glaucoma

• Treatment of myasthenia gravis

• Treatment of urinary retention and intestinal stasis

Drugs Affecting the Parasympathetic Nervous System

Clinical Use

• Treatment of Alzheimer’s disease.

• Antidote to skeletal muscle blockers.

• Antidotes to anticholinergic drug poisoning.

Drugs Affecting the Parasympathetic Nervous System

Indirect-ActingCholinergic Drug

Reversible

AmbenoniumEdrophoniumNeostigmine

PhysostigminePyridostigmine

Irreversible

Isoflurophate

Drugs Affecting the Parasympathetic Nervous System

Adverse and Toxic Effect

• Nausea

• Vomiting

• Diarrhea

• Blurred vision

Drugs Affecting the Parasympathetic Nervous System

Adverse and Toxic Effect

• Excessive sweating

• Muscular tremors

• Bronchoconstriction

• Bradycardia

Drugs Affecting the Parasympathetic Nervous System

Adverse and Toxic Effect

• Hypotension

• Mucular paralysis

• Respiratory arrest

Drugs Affecting the Parasympathetic Nervous System

Cholinergic Crisis

• Excessive drug dosage in patients with myasthenia gravis.

• High concentration of ACH causes excessive stimulation of the muscarinic receptors.

• High concentration of ACH causes blockade of nicotinic receptor.

Drugs Affecting the Parasympathetic Nervous System

Treatment

• Stop anticholinesterase drug administration.

• Give atropine to block the effect of excess muscarinic stimulation

Drugs Affecting the Parasympathetic Nervous System

Cholinergic Crisis

• Excessive exposure to sprays containing derivatives of irreversible anticholinesterase.

• High concentration of ACH causes excessive stimulation of the muscarinic receptors.

• High concentration of ACH causes blockade of nicotinic receptor.

Drugs Affecting the Parasympathetic Nervous System

Treatment

• Remove person from the exposure.

• Give Pralidoxime to reactivate the anticholinesterase enzyme.

• Give atropine to block the effect of excess muscarinic stimulation

Drugs Affecting the Parasympathetic Nervous System

Anticholinergic Drugs

• Binds to muscarinic receptors.

• Act by competitive antagonism of ACH.

• Prototype drugs: Belladonna alkaloids, atropine and scopolamine

Drugs Affecting the Parasympathetic Nervous SystemPharmacological Action

• Increase heart rate.

• Increase the secretions of the respiratory tract and may cause bronchoconstriction.

• Reduce salivary and GI tract.

• Inhibit urinary peristalsis and voiding of urine.

Drugs Affecting the Parasympathetic Nervous SystemPharmacological Action

• Depressant effects on the CNS causing drowsiness and sedation.

• At high doses cause both stimulation and depression of the CNS

• At toxic doses excitation, delirium, hallucination and profound CNS depression leading to respiratory arrest and death.

Drugs Affecting the Parasympathetic Nervous System

Ocular Effect

• Mydriasis

• Cycloplegia

• Increases Intraocular pressure.

Drugs Affecting the Parasympathetic Nervous SystemAdverse and Toxic Effect

• Cause by excessive blockage of the Parasympathetic Nervous System.

• Dry mouth.

• Visual disturbances

• Urinary retention

• Constipation.

Drugs Affecting the Parasympathetic Nervous System

Adverse and Toxic Effect

• Dryness of the skin

• Flushing

• Hyperpyrexia

• CNS stimulation and depression

Drugs Affecting the Parasympathetic Nervous System

Anticholinergic Drugs

Belladonna Alkaloids

AtropineScopolamineHyoscyamine

Semisynthetic Drug

Homatropine

Synthetic Drugs

DiclyclomineIsopropamidePropanthelineMethantheline

Nursing Implications Assess for allergies, presence of GI or GU obstructions,

asthma, peptic ulcer disease, or coronary artery disease

Perform baseline assessment of vital signs and systems overview

Medications should be taken as ordered and not abruptly stopped

The doses should be spread evenly apart to optimize the effects of the medication

Overdosing can cause life-threatening problems. Only physicians should adjust the dosages

Nursing Implications

• Encourage patients with myasthenia gravis to take medication 30 minutes before eating to help improve chewing and swallowing

• When cholinergic drugs are prescribed for Alzheimer’s disease, be honest with caregivers and patients that the drugs are for management of symptoms, not a cure

• Therapeutic effects of anti-Alzheimer’s drugs may not occur for up to 6 weeks

Nursing Implications

Monitor for therapeutic effects Alleviated signs and symptoms of myasthenia gravis In postoperative patients with decreased GI peristalsis,

look for:

Increased bowel sounds Passage of flatus Occurrence of bowel movements

In patients with urinary retention/hypotonic bladder, urination should occur within 60 minutes of bethanechol administration

• ALSO monitor for adverse effects

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