ANTICHOLINERGIC DRUGS Prof. Alhaider Pharmacology Department Prof. Hanan Hagar Pharmacology Department
Feb 24, 2016
ANTICHOLINERGIC DRUGS
Prof. Alhaider Pharmacology Department
Prof. Hanan HagarPharmacology Department
What students should know:Student should be able to :
• Describe Kinetics of muscarinic antagonists • The effects of atropine on the major organ systems.• To list the clinical uses of muscarinic antagonists.• To know adverse effects & contraindications of anticholinergic drugs.• To identify at least one antimuscarinic agent for each of the following special uses:mydriasis, cyclopedia, peptic ulcer & parkinsonism.
Anticholinergic drugs
are drugs that block cholinergic receptors.
Anticholinergic drugs
Antimuscarinics(Parasympatholytics)
Antinicotinics
synthetic atropine substitutes
Ganglionic blockers
Neuromuscular blockers
Anticholinergic drugs
Naturally occurring alkaloids
synthetic atropine substitutes
Antimuscarinics
Naturally occurring alkaloids
Antimuscarinics
Natural alkaloidsDrugs as : Atropine - Hyoscine • Esters of tropic acid and tertiary amines• Lipid soluble• Good oral absorption• Good distribution• Cross blood brain barrier (have CNS actions)
AntimuscarinicsMuscarinic antagonists
Synthetic atropine substitutes
AntimuscarinicsMuscarinic antagonists
BenztropineHomatropineTropicamaidePirenzepineIpratropiumGlycopyrrolateOxybutynin
Mechanism of action • Reversible competitive blockade of muscarinic
receptors.• Atropine can block all muscarinic receptors.
Antimuscarinic drugs
CNS– Sedation – Antiemetic effect (block vomiting center)– antiparkinsonian effect (block basal
ganglia).
– Toxic dose: Hyperthermia - excitement-hallucination.
Pharmacological effects ofatropine
Cardiovascular system (CVS) Tachycardia (increase in heart rate) AV conduction ( + ve dromotropic effect) Therapeutic dose: Vasodilatation induced
by cholinomimetics. Toxic dose: Cutaneous vasodilatation
(atropine flush).
Respiratory system Relaxation of bronchial muscles
(bronchodilator) Bronchial secretion viscosity
EyePassive mydriasis
due to paralysis of circular muscleCycloplegia (loss of near accommodation) due to paralysis of ciliary muscle.Loss of light reflex. increase I.O.P # glaucoma. Lacrimal secretion sandy eye
Secretions
¯ Salivary secretion ( Dry mouth ). Sweating Dry skin Fever in infants and
children. Bronchial secretion Viscosity¯ Lacrimal secretion Sandy eye
GIT– Relaxation of smooth muscles.– GIT motility Antispasmodic effect.– Sphincter contractions– Constipation
Urinary Tract– Relaxation of smooth muscles of urinary
bladder.– Sphincter contraction. – Urinary retention.
Hyoscine (SCOPOLAMINE)
What is difference between atropine and hyoscine?
Hyoscine has• Shorter duration of action• More CNS depressant action• Antiemetics action in motion sickness• Can produce amnesia. • Less CVS effect
Anticholinergic actions Cholinergic actions
relaxation (mydriasis)
relaxation (cycloplegia) loss of accommodation
EyeCircular muscle of iris
Contraction (miosis)Ciliary muscles Contraction
(accommodation for near vision)
Tachycardia H.RHeartbradycardia ( H.R.)
Relaxation of musclescontraction of sphincter Urinary retention
Urinary bladderContraction of musclesRelaxation of sphincter
Anticholinergic drugs Cholinergic drugs
Decrease all secretionsExocrine glandsIncrease of sweat, saliva, lacrimal, bronchial, intestinal secretions
peristalsis secretionContraction of sphincter
constipation
GIT peristalsis secretion relaxation of sphincter
1. Bronchodilatation2. Decrease secretion
Lung1. Bronchoconstriction2. bronchial secretion
Uses organ DrugsPre-anesthetic medication
Antispasmodic CNS Atropine
Pre-anesthetic medication, Motion sickness, antispasmodic
CNS Hyoscine
Parkinson's disease CNS BenztropineFundus examination of eye Eye Homatropine
asthma, COPD, inhalation Respiratory system
Ipratropium
Peptic ulcer Stomach PirenzepineAntispasmodics in
hypermotilityGIT Glycopyyrolate
Urinary urgency, Urinary incontinence
GUT Oxybutynin
Uses of antimuscarinic drugs
Adverse effectsEye: Blurred vision – Mydriasis CVS: Tachycardia - Atropine flushGUT: Urinary retention GIT: Constipation, paralytic ileusSecretions: Dryness of mouth , Sandy eyeIncreased body temperature.CNS: sedation, hallucination, excitation (Toxic dose).
Treatment– Gastric lavage.– Anticonvulsant.– Cooling blanket.
Antidote: Physostigmine ( IV slowly).
Contraindications– Glaucoma (angle closure glaucoma)– Tachycardia– Prostate hypertrophy in old patients.– Constipation, paralytic ileus, intestinal
obstruction.– Children in case of atropine
Can antimuscarinic drugs reverse the actionof neostigmine on skeletal muscles?
SUMMARY
– Antimuscarinics reverse action of cholinomimetics on muscarinic receptors.
– Are useful in many applications including intestinal spasm, constipation, urinary retention, vomiting, parkinsonism, asthma and peptic ulcer.
– Are contraindicated in constipation, Prostate hypertrophy, tachycardia and glaucoma.
Thank you
Questions ?