Drugs Used For Affective Disorders By Prof. Abdulqader Alhaider Prof. Abdulqader Alhaider.
ANTICHOLINERGIC DRUGS Profs. Abdulqader Alhaider and Hanan Hagar Pharmacology Department.
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Transcript of ANTICHOLINERGIC DRUGS Profs. Abdulqader Alhaider and Hanan Hagar Pharmacology Department.
ANTICHOLINERGIC DRUGSANTICHOLINERGIC DRUGSANTICHOLINERGIC DRUGSANTICHOLINERGIC DRUGS
Profs. Abdulqader Alhaider and Hanan HagarPharmacology Department
What students should know:What students should know:Student should be able to : Student should be able to :
• Describe Kinetics of muscarinic antagonists Describe Kinetics of muscarinic antagonists • The effects of atropine on the major organ systems.The effects of atropine on the major organ systems.• To list the clinical uses of muscarinic antagonistsTo list the clinical uses of muscarinic antagonists.• To know adverse effectsTo know adverse effects & contraindications of anticholinergic & contraindications of anticholinergic drugs.drugs.• To identify at least one antimuscarinic agent for each of theTo identify at least one antimuscarinic agent for each of the following special uses:mydriasis, cyclopedia, peptic ulcer & following special uses:mydriasis, cyclopedia, peptic ulcer & parkinsonism.parkinsonism.
Anticholinergic drugsAnticholinergic drugs
are drugs that block cholinergic receptors. Two types are available
1. Nicotinic blockers (antinicotinics).Ganglionic blockers (not used Clinically Why?)
Neuromuscular blockers (Skeletal Muscle Relaxants)
2. Muscarinic blockers (antimuscarinics)Naturally occurring alkaloids (e.g: Atropine)
Synthetic atropine substitutes.
Anticholinergic drugsAnticholinergic drugs
Antimuscarinics(Parasympatholytics)
Antinicotinics
synthetic atropine substitutes
Ganglionic blockers
Neuromuscular blockers
Anticholinergic drugs Anticholinergic drugs
Naturally occurring alkaloids
• History (Thousants of years)•Atropine (Hyoscyamine)• Hyoscine (scopolamine)• Esters of tropic acid and tertiary amines• Lipid soluble• Good oral absorption• Good distribution• Cross blood brain barrier (have CNS actions)
Natural alkaloids
Muscarinic antagonistsMuscarinic antagonists
Synthetic atropine substitutes
Muscarinic antagonistsMuscarinic antagonists
Tertiary amines
Lipid solublecentral actions
BenztropineHomatropineTropicamaidePirenzepineOxybutynin
Tertiary amines
Lipid solublecentral actions
BenztropineHomatropineTropicamaidePirenzepineOxybutynin
Quaternary amines
Polar, water solubleNo CNS effects
IpratropiumGlycopyrrolate
N+N+
Quaternary amines
Polar, water solubleNo CNS effects
IpratropiumGlycopyrrolate
N+N+
Muscarinic antagonistsMuscarinic antagonists
Quaternary aminesQuaternary amines
DRUG Pharmacokinetics
Natural alkaloidsAtropine (Hyosyamine)Hyoscine (scopolamine)
Tertiary amines, lipid soluble, well absorbed, well distributed, good penetration to CNS
Synthetic atropine substitutes
Benztropine Tertiary amine
Tropicamide Homatropine
Tertiary amines
Ipratropium Quaternary amines, not absorbed well, poor distribution, no CNS effects
Pirenzepine Tertiary amine
GlycopyrrolateOxyphenonium
Quaternary amines
Oxybutinin Tertiary amine
Antimuscarinic drugs Antimuscarinic drugs
Mechanism of action
• Reversible competitive blockade of muscarinic
receptors.
Can antimuscarinic drugs reverse the action of
Ach on skeletal muscles?
Antimuscarinic drugs Antimuscarinic drugs
CNS– CNS depression – Antiemetic effect (block vomiting center)– antiparkinsonian effect (block ACH at
basal ganglia).
– Toxic dose: Hyperthermia - excitement-hallucination.
Pharmacological Effects ofPharmacological Effects ofAntimuscarinic Drugs Antimuscarinic Drugs
Cardiovascular system (CVS) Tachycardia (increase heart rate) AV conduction ( + ve dromotropic effect) Therapeutic dose: Vasodilatation induced
by cholinomimetics. Toxic dose: Cutaneous vasodilatation
(atropine flush).
Respiratory system Bronchial Relaxation (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 (worsens 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 ureters.– Sphincter contraction. – Urinary retention (worsens prostate
hypertrophy).
Hyoscine (SCOPOLAMINE)
What is difference between atropine and hyoscine?
Hyoscine has• Shorter duration of action• More CNS depressant action• Antiemetics action in motion sickness• Amnesic action. • Less CVS effect
Can you put a question for exam?
Cholinergic actions Anticholinergic actions
Eye
1. Contraction of circular muscle of iris (miosis)
2. Contraction of ciliary muscles for near vision
1. Mydriasis
2. Cycloplegia
relaxation of ciliary muscles
Heart
bradycardia ( heart rate ) Tachycardia ( heart rate)
Urinary bladder
Contraction of muscles
Relaxation of sphincter
Relaxation of muscles
contraction of sphincter
Cholinergic drugs Anticholinergic drugsExocrine glands
Increase of sweat, saliva, lacrimal, bronchial, intestinal secretions
Decrease all secretion
GIT
peristalsis
secretion
relaxation of sphincter
peristalsis secretionContraction of sphincter
Lung
1. Bronchoconstriction
2. bronchial secretion
1. Bronchodilatation2. Decrease secretion
Drugs organ Uses
Atropine CNS Cardiac Arrest How?Rx of pesticide Toxicity
Hyoscine CNS Preanesthetic medication, Motion sickness, antispasmodic
Benztropine CNS Parkinson's disease
TropicamideHomatropine
Eye Fundus examination of eye
Ipratropium Respiratory system
asthma, COPD, inhalation
Pirenzepine Stomach Peptic ulcer
GlycopyyrolatePropantheline
GIT Antispasmodics in hypermotility
Oxybutynin GUT Urinary urgency, Urinary incontinence
Uses of antimuscarinic drugs Uses of antimuscarinic drugs
• Adverse effects (usually can be observed with antidepressant s and antipsychotics)– Eye: Blurred vision – Mydriasis – CVS: Tachycardia - Atropine flush– GUT: Urinary retention – GIT: Constipation, paralytic ileus– Secretions: Dryness of mouth , Sandy eye– Increased body temperature.– CNS: sedation, hallucination, excitation (Toxic dose).
• Treatment– Gastric lavage.– Anticonvulsant.– Cooling blanket.
• Antidote: Physostigmine ( IV slowly).
• Treatment of anticholinergic Toxicities – 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
Thank you
Questions ?