Akshaya Ranade is teaching live on Unacademy Plus
Drugs acting on ANS By Dr. Akshaya unacademy.com/user/akshaya949
Cholinergic receptors M1: ON SECRETORY GLANDS: salivation, acid secretion, lacrimation N: SKELETAL MUSCLE END PLATE: contraction N AUTONOMIC GANGLIA, ADRENAL MEDULLA: epinephrine secretiorn M2: HEART: HEART RATE M3: SMOOTH MUSCLES: contraction, bronchospasm, urination M3: PUPIL,CILIARY MUSCLES: miosis, aqueous humour flow
Action Blocks all subtypes of M receptors 1. CNS: overall stimulant (hyoscine is depressant), anti motion sickness action (on vestibular excitation), suppresses tremor (basal ganglia), high dose causes cortical excitation 2. CVS tachycardia (blockade of M2 on SA node), not much effect on BP 3. EYE: mydriasis, abolition of light reflex and cycloplegia( hence photophobia and blurring of near vision) Smooth muscles : M3 block, reduced peristalsis, bronchodilation, bladder relaxation Glands: reduced sweat and saliva (M2 block), skin and eyes dryness, rise in body temperature 4. 5.
Hyoscine butyl bromide Atropine methonitrate lpratropium bromide For Esophageal and gastric spastic condition For abdominal colic and hyperacidity By inhalation in COPD and bronchial asthma as prophylactic Tiotropium bromide Propantheline Oxyphenonium Clidinium Long lasting bronchodilation For peptic ulcer and gastritis (15-30 mg oral) Peptic ulcer and git hypermotility (5-10 mg oral) Used with benzodiagepines for nervous dyspepsia, gastritis Pipengolate Flatulent dyspepsia, git spasm methylbromide isopropamide Glycopyrrolate Hyperacidity, irritable bowel with mental disorder Preanaesthetic medication
Dicyclomine 20mg oral/im antispasmodic, in motion sickness, morning sickness, antiemetic property, dysmenorrhoea, irritable bowel, also given with paracetamol Valethamate 10 mg oral / 8mg im Dilatation of cervix in delayed labour, visceral antispasmodic Pirengepine M1 selective to inhibit gastric secretions
Uses of anticholinergic drugs 1. Antisecretory: as pre anaesthetics, peptic ulcer, pulmonary embolism 2. Antispasmodic: intestinal or renal colic, diarrhoea, spastic constipation, IBS, gastritis, in urinary frequency and urgency, dysmenorrhoea Bronchial asthma, COPD, asthmatic bronchitis Mydriatic and cycloplegic : diagnostic for testing refractive error (tropicamide, homatropine), therapeutic for iritis, choroiditis, keratitis, corneal ulcer Cardiac vagolytic to counter bradycardia Parkinsonism Motion sickness: hyoscine (also used as lie detector in WW 2) Antidote for: anti ChE, mushroom, Neostigmine, cobra venom, decurarization 3. 4. 5. 6. 7. 8.
Side effects and toxicity 1. Hot as a hare - increased body temperature Blind as a bat - dilated pupils & blurry vision Dry as a bone - dry mouth, dry skin, dry eyes Red as a beet - flushed face, lightheadedness or fainting Mad as a hatter - confusion, anxiety, rapid HR, headache 2. Can't see, Can't pee, Can't spit, Can't shit.
Diagnosis of toxicity 5mg methacholine or 1mg neostigmine s.c fail to induce muscarinic effects Treatment : gastric lavage with tannic acid, dark quiet room, cold sponging and ice bags to reduce temperature, physostigmine 1-3 mg s.c or iv Contraindications for atropinic drugs: narrow angle glaucoma, elderly male with BPH