Anti-Cholinergic Drugs

Tropicamide

REF: khurana 4th ed p. 68

• shortest acting mydriatic – Tropicamide
• Only mydriatic and not cycloplegic – phenylephrine
• Used in children – Atropine

Floppy mitral valve REF: Pediatrics: A Concise Text – Text – SK Kabra, RN Srivastava Page 135

Repeat in December 2011

The murmur is the clinching point here as the patient is having ostium primum type of ASD with MR and Ostium primum defect alone cannot produce such murmur and in question it is already mentioned that the patient is having ASD, Floppy mitral valve should be the answer.

“Presence of pansystolic murmur of mitral regurgitation (MR) in a patient with ASD suggests the presence of ostium primum defect with cleft mitral laeflet or floppy mitral valve with mitral valve prolapsed”

“ECG shows right axis deviation in ostium secundum ASD and extreme left axis deviation in ostium primum ASD”

“Clinical presentation of ostium primum is similar to ostium secundum except that there may be a mitral systolic murmur due to MR and ECG shows left axis deviation”

Physostigmine is effective in the treatment of central anticholinergic toxicity caused by overdoses of atropine or scopolamine.

In addition, it reverses some of the central nervous system depression and delirium associated with use of

benzodiazepines and volatile anesthetics. 

Tissues most sensitive to atropine are the salivary, bronchial, and sweat glands. Secretion of acid by the gastric parietal cells is the least sensitive.

• Other factors that influence the cholinergic tone of various organs.
• Variations in synaptic gaps

• Plants and mushrooms containing anticholinergic alkaloids include
  • Jimsonweed (Datura stramonium)
  • Deadly nightshade (Atropa belladonna)
  • Fly agaric (Amanita muscaria)
• The root of Atropa belladonna contains 82-97% of hyoscyamine, 3-15% atropine, and up to 2.5% scopolamine.
• Anticholinergic agents competitively antagonize the effects of acetylcholine at peripheral muscarinic and central receptors.

Also know: LES pressure is higher in the supine position than in the upright position.

Tropicamide is the quickest (20-40min) and shortest acting (3-6hours) mydriatic.

Atropine is a potent mydriatic but its slow and has long lasting action. With it, pupil dilates in 30-40min but cycloplegia takes 1-3hours.

• Restlessness and excited behavior with 
• Dryness and flushing of the skin of the face
• Dry mouth
• Fever
• Inhibition of sweating
• Tachycardia 

D i.e. Glucoma

Atropine is contraindicated in narrow angle glucomaQ.

Atropine is used as antidote for various poisons with cholinergic symptoms as – Anticholine Esterase (Organophosphorus) poisoning, Neostigmine / Pyridostigmine / Plzysostigmine overdose, Mushroom poisoningQ

Ans. is ‘d’ i.e., Is a competitive antagonist of acetylcholine

o Atropine acts as competitive antagonist at muscarinic receptors. It has no activity on nicotinic receptors and has nothing to do with Ach release.

Ans. is ‘c’ i.e., Bradycardia

o Atropine is an anticholinergic drug and thus causes tachycardia (not bradycardia)

Ans. is ‘a’ i.e., Increase bowel sound; ‘c’ i.e., Hypotension

o Whenever there is peristalatic activity, there will be bowel sound —) Peristalasis causes movement of gases (that are present in the bowel) which results in bowel sound.

o When there is paralysis of bowel smooth muscles (paralytic ileus), bowel sound will be absent.

o Now you can easily understand that

i) Drugs that increase peristalasis (e.g. cholinergic drugs) will increase bowel sound.

ii) Drugs that decrease peristalasis (e.g. anticholinergic drugs —) atropine) will decrease bowel sound. About other options

There are no changes in blood pressure or cardiac output — Goodman & Gilman Atropine causes tachycardia.

Ans. is ‘b’ i.e., Bronchoconstriction

Atropine causes bronchodilation.

Ans. is ‘d’ i.e., Miotic

CLINICAL USES OFATROPINE

Remember – ATROPA

A As mydriatic – cycloplegic

T —> ‘Traveller’s diarrhoea

R —> Rapid (early) onset mushroom poisoning

0 —> Organophosphate poisoning

P —> Preanaesthetic medication

A Arrhythmias (brady-arrhythmias)

Atropine is also used with neostigmine in mysthenia gravis to decrease anti,nuscarinic side effects of neostigmine —› As atropine blocks muscarinic receptors, use of atropine prevents muscarinic side effects of neostigmine, while neostigmine retains its benficial effects in mysthenics which are due to nicotinic receptors.

Ans. is ‘c’ i.e., Acts on central and peripheral cholinergic receptors

o In organophosphate poisoning, atropine counteracts the peripheral muscarinic symptoms and at higher doses central effects as well.

o Atropine does not reverse nicotinic action i.e., peripheral muscular paralysis.

Ans. is ‘c’ i.e., Muscarinic receptor inhibition

Oxybutnin

o Oxybutynin is an anticholinergic drug.

o It is relatively selective for M₃ receptors, so it has selective action on urinary bladder.

• Because of its vesicoselective action it is used for detrusor instability and urinary incontinence.

Ans. is ‘a’ i.e., Pirenzepine

Pirenzepine is a selective M₁  anti-cholinergic & usual doses inhibit acid secretion by 40-50%.

Ans. is ‘c’ i.e., Domperidone

o Drugs used are :

a)         Anticholinergics —> Hyoscine (Scopolamine), Dicyclomine.

b)      H_l-antihistaminic —> Promethazine, cyclizine, meclizine, cinnarizine, etc.

o Hyoscine (scopolamine) is the most effective drug for motion sickness.

About option ‘c’

o Domperidone is a prokinetic drug and acts by D₂ blockade. It is ineffective in motion sickness as vestibular pathway does not involve dopaminergic link.

D i.e. Pirenzepine

D i.e. 1% Atropine ointment

A i.e. Atropine sulphate ointment

A i.e. Atropine

• Treatment of hypertensive uveitis is treatment of acute iridocyclitis (Mydriatic-cycloplegic-steroid­antibiotics), topical (3 blocker (e.g. timolol), carbonic anhydrase inhibitor (acetazolamide) dipivefrine.
• Secondary glaucoma Q (due to posterior synechiae formation) is the m.c. complication of recurrent anterior uveitis.
• Miotics eg pilocarpine or other cholinergics are contraindicated in treatment of anterior uveitis Q as these increase chances of synechiae formation. It is also contraindicated in malignant glaucoma Q & post inflammatory glaucoma Q.

C i.e. Iridocyclitis

• Steroid > Atropine is drug of choice for acute iridocyclitis (anterior uveitis).Q

Atropine is contraindicated in glucomas where as pilocarpine is contraindicated in anterior uveitis. Q

Ans. Irregular dilatation of pupil with atropine in the presence of segmental posterior synechiae

Ans: B i.e. Hyoscine

• Metoclopramide is an effective and popular drug for many types of vomiting – postoperative, drug induced, disease associated (migraine), radiation sickness, etc.
• Hyoscine is the most effective antiemetic drug for motion sickness and is not effective in vomiting of other etiologies
• Ondansetron belongs to a new class of antiemetic drugs developed to control cancer chemotherapy/radiotherapy induced vomiting
• Neuroleptics/antipsychotics have broad spectrum antiemetic action effective in drug induced and post-anaesthetic nausea and vomiting etc.

Ans. Atropine

Ans. is `d’ i.e., Hyoscine

Motion sickness is more easily prevented than cured.

Transdermal hyoscine (scopolamine) is the best agent for the prevention of /notion sickness.

Antihistamines can also be used for prevention.

Ans. is ‘a’ i.e., Valethamate

Anticholinergic drugs

1. Natural alkaloids Atropine, Hyoscine (Scopolamine).
2. Semisvnthetic derivatives Homatropine, Atropine methonitrate, Hyoscine butyl bromide, Ipratropium bromide, Tiotropium bromide.
3. Synthetic compounds

a) Mydriatics : Cyclopentolate, Tropicamide.

b) Antisecretory-antispasmodics :

1. Quaternary compounds : Propantheline, Oxypheonium, Clidinium, Pipenzolate methyl bromide, Isopropamide. Glycopyrolate.
2. Tertiary amines : Dicyclomine, Valethamate, Pirenzepine

c) Vasicosective : Oxbutynin, Flavoxate, Toltcrodine.

d) Antiparkinsonian : Trihexphenidyl (Benzhexol), Procyclidine. Biperiden.

Ans. b. Glycopyrrolate

Glycopyrrolate is a synthetic quaternary anticholinergic drug, which doesn’t cross the blood brain barrier and completely lacks central effects.

Glycopyrrolate is a synthetic quaternary anticholinergic drug, which doesn’t crosses the blood brain barrier and completely lacks central effects.

Glycopyrrolate

• Glycopyrrolate, like other anticholinergic (antimuscarinic) agents, inhibits the action of acetylcholine on structures innervated by postganglionic cholinergic nerves and on smooth muscles that respond to acetylcholine but lack cholinergic innervation.
• It diminishes the volume and free acidity of gastric secretions and controls excessive pharyngeal, tracheal, and bronchial secretions^Q
• Glycopyrrolate antagonizes muscarinic symptoms° (e.g., bronchorrhea, bronchospasm, bradycardia, and intestinal hypermotility) induced by cholinergic drugs such as the anticholinesterases.
• The highly polar quaternary ammonium group of glycopyrrolate limits its passage across lipid membranes, such as the blood-brain barrier^Q

Ans. is ‘c’ i.e., Hyoscine 

“Transdermal patches ofNTG, fentanyl, nicotine and estradial are available in India, where as those of isosorbide dinitrate, hyoscine and clonidine are marketed elsewhere”. — KDT