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Anticholinergics.pptx
- 1. Autonomic nervous system AnticholinergicDrugs/ Parasympatholytics/ Antimuscarinics Department : Pharmacology Course: Pharmacology
- 2. • Drugs thatblock or inhibit the actions of acetylcholine (ACh) in the parasympathetic nervous system (PSNS) • Also called cholinergic blocking agents or parasympatholytics • Often referred to as anticholinergics or antimuscarinics
- 3. • Competitive antagonists •Compete with acetylcholine • Block acetylcholine at the muscarinic receptors in the PSNS • Reversible blockade of acetylcholine at muscarinic receptors by competitive binding • (reversal by increasing acetylcholine or agonist ----> decreased blockade) • Once these drugs bind to receptors, they inhibit nerve transmission at these receptors.
- 5. • Prototype antimuscarinicdrug - derived from Atropa belladonna (deadly nightshade) and Datura stramonium (thorn apple) • History: • plant extracts were used as cosmetic eye drops • hence the name belladonna or "beautiful lady" in Italian
- 6. Cardiovascular effects- • Decreasedcardiovascular response to vagal stimulation resulting in tachycardia • Mainly, tachycardia due to antagonism of the vagal affect. • Vascular – no (direct) effect – except, dilate cutaneous vessels (red as a beet) – block hypotensive effect of muscarinic agonists
- 7. CNS – • Atnormal doses atropine stimulates medullary centers, However, at higher doses produce excitement, agitation, hallucinations and coma. • Depresses vestibular excitation and has anti motion sickness properties • Supresses tremor and rigidity of parkinsonism by blocking cholinergic overactivity in basal ganglia.
- 8. Eye: • Dilated pupils(mydriasis) • Blocks muscarenic innervations on the circular muscles (Mydriasis) and relaxes cilairy muscles (Cycloplegia) • worsens glaucoma Gastrointestinal: • Relax smooth muscles of GI tract • Decrease intestinal and gastric secretions • Decrease motility and peristalsis • antispasmodic effect • Sphincter contraction
- 9. Respiratory system - •Decreases bronchial secretion (used as preanesthetic Medication,COPD) • Dilated bronchial airways (used for treatment of Asthma) Genitourinary - • Relaxes detrusor muscle • Increased constriction of internal sphincter • Result: urinary retention • Relaxation of smooth muscles of ureters. • Therefore, they are contraindicated for prostate hypertrophy patients.
- 10. Glandular – • Salivary secretion (Dry mouth) • gastric Acid (used for Peptic Ulcer ) • Sweating Dry skin Fever in infants and children. • Bronchial Secretion (used for COPD)
- 11. Central Nervous SystemDisorders- • Parkinson’s disease – Benztropine, Trihexyphenidyl • Those who cannot take Levodopa • Helpful in decreasing salivation, spasticity and tremors • Motion Sickness (Scopolamine) • Drug-induced extrapyramidal reactions(due to antipsychotics)
- 12. CVS – •Atropine is used to increase heart rate in symptomatic bradycardias. • Sinus node dysfunction • Symptomatic second-degree heart block • Sinus or nodal bradycardia (due to myocardial infarction)
- 13. Respiratory system- • Decreasedsecretions from nose, mouth, pharynx, bronchi • Relaxed smooth muscles in bronchi and bronchioles • Decreased airway resistance • Bronchodilation Respiratory agents are used to treat: • Exercise-induced bronchospasms • Chronic bronchitis • Asthma • Chronic obstructive pulmonary disease • Ipratropium as inhalation (or Tiotropium)
- 14. Gastrointestinal: • Blockade ofPSNS results in: • Decreased secretions • Relaxation of smooth muscle • Decreased GI motility and peristalsis Gastrointestinal agents are used to treat: • Peptic Ulcer: Pirenzepine • As antispasmodic :Butylscopolamine • Irritable bowel disease: Propantheline • GI hypersecretory states
- 15. Urologic disorders- • Antispasmodiceffects seen in overactive bladder and in urinary incontinence - Oxybutynin • Detrusor hyper-reflexia, • Enuresis -Increase bladder capacity -Decrease bladder pressure
- 16. Opthalmological Disorders- • Homatropine,tropicamide •Accurate measurement of refractive error in uncooperative patients (e.g, children) • Examination of retina (Mydriasis)
- 17. Body System Cardiovascular CNS Side/Adverse Effects Increasedheart rate, dysrhythmias CNS excitation, restlessness, irritability, disorientation, hallucinations,delirium
- 18. Body System Eye Gastrointestinal Side/Adverse Effects Dilatedpupils, decreased visual accommodation, increased intraocular pressure Decreased salivation, decreased gastric secretions, decreased motility
- 19. Body System Genitourinary Side/Adverse Effects Urinaryretention Glandular Decreased sweating Respiratory Decreased bronchial secretions
- 20. • Anticholinergic overdosesyndrome (Belladona poisoning- consumption of seeds or berries of belladona or dhatura plant) is characterized by: Hyperthermia, delirium, dry mouth, tacycardia, ileus, urinary retention. Seizures, coma and respiratory arrest may occur. • Treatment – Gastric lavage with tannic acid, cold sponging or ice bags, Physostigmine s.c. or i.v., diazepam to control convulsions.
- 22. • Glaucoma • Prostatichypertrophy • Urinary tract obstruction • Gastrointestinal tract obstruction • Infectious diarrhea • Reflux esophagitis • Tachyarrhythmias • Angina • Hyperthyroidism • Pregnancy
- 23. • Atropine -prototype. Antidote in OP Poisoning. • Ipratropium - Useful in rhinorrhea.Also excellent bronchodilator. • Scopolamine - depresses CNS and causes amnesia, drowsiness, euphoria, relaxation and sleep. Also good for motion sickness. Given parenterally, orally and transdermally. • Benztropine - temporary use in Parkinson’s disease. Useful for dystonic reactions caused by antipsychotics.
- 24. • Trihexyphenidyl -also used for treating EPS by some antipsychotics. Contraindicated in glaucoma. • Flavoxate - relieves dysuria, urgency, frequency, and pain with GU infections • Oxybutynin - has direct antispasmodic effects on smooth muscle and anticholinergic effects. Decreases frequency of voiding.