Pharmacology is hard and easy subject, Cheat Sheet of Pharmacology

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Prepared By: Nehal V. Trambadiya Asst. Professor Smt. N. M. Padalia Pharmacy College

 Conventionally, anticholinergic drugs are those which block actions of ACh on autonomic effectors and in the CNS exerted through muscarinic receptors.  Though nicotinic antagonists also block certain actions of ACh, they are generally referred to as ‘ganglion blockers’ and ‘neuromuscular blockers’.  Atropine, the prototype drug of this class, is highly selective for muscarinic receptors

3. Synthetic compound: a) Mydriatics: -Cyclophosphamide -Tropicamide b) Antisycretory and antispasmodics: 

• Quaternary compound -Propantheline -Oxyphenonium -Clidinium -Pipenzolate methyl bromide -Isopropamide -Glycopyrolate

Tertiary amine: -Dicyclomine -Oxybutynin -Flevoxate -Pirenzepine -Telenzepine c) Antiparkinsonian:

• Benzhexol -Procyclidine -Biperiden -Benzatropine -Cycrimide -Ethopropazine

Pharmacological action:

1. CNS: -Stimulates cerebral cortex and the medulla. This stimulation is followed by depression, stupor(impaired consciousness) and coma. -On small dose  Stimulates respiration -On large dose  depression of respiration

• Depresses vestibular excitation hence use in antimotion sickness property. -By blocking cholinergic over activity in basal ganglia  suppresses tremor, rigidity of parkinsonism.

3) Gastro intestinal tract:

-Small dose  decrease gastric acid secretion and

reduction motor activity of intestine.

-Relaxes the gall bladder and bile duct.

4) Smooth muscle:

-Relaxes bronchi and bronchioles  resulting

widening of the airway.

-Bronchial secretion are dried up  lead to mucous

plug formation and obstruction.

-Ureter  Tone and contraction is decreases.

-Detrusor muscle of bladder is relaxes.

 urinary retention can occur in older males with prostatic hypertrophy

5) Effect on secretion: -Markedly decrease the sweat, salivary, tracheobronchial and lachrymal secretion by M receptor blocking. (Hexahydrosiladifenidol, Darifenacin)

• Skin and eye become dry.
• Talking and swallowing become difficult. 6) Effect on eye: -Intrinsic muscle of eye have a dual nerve supply.

1. Parasympathetic carried via oculomotor nerve  stimulate the constrictor (sphincter) pupillae  miosis.

PHARMACOKINETICS  Atropine and hyoscine are rapidly absorbed from g.i.t. Applied to eyes they freely penetrate cornea.  Passage across blood-brain barrier is somewhat restricted.  About 50% of atropine is metabolized in liver and rest is excreted unchanged in urine.  It has a t½ of 3–4 hours.

Therapeutic use:

CNS disorder  motion sickness, parkinson’s

disease

Antispasmodic  relaxes intestinal, biliary and

urinary tract, Bronchodilator in bronchial asthma

Antisecretory agent  reduces the gastric acid

secretion, sweating

Ophthalmic use  produces mydriasis and

cycloplegia(paralysis of ciliary muscle- loss of

accomodation), in corneal ulcer (homatropine)

Cardiac stimulant use to treat the heart block due to

digitalis toxicity.

As antidote in anticholinesterase poisoning.

Atropine / belladonna poisoning: Due to over dose of atropine (1gm)  Symptoms: Severely dryness of mouth Wide pupillary dilatation Dysphasia Tachycardia Redness of skin, Rise body temp. Muscle inccordination Delirium, hallucination Stupor, coma Respiratory collapse

 Diagnosis Methacholine 5 mg or neostigmine 1 mg s.c. fails to induce typical muscarinic effects.

ATROPINE HYOSCINE CNS effect Low dose High dose Excitatory Mild Strong Depressant Excitation Anticholinergic Property More potent on heart, bronchial muscle and intestine More potent on eye, secretary gland Duration of action Longer Shorter Antimotion sickness ++ +++

Drug Rout Dose Use Hyoscine butyl bromide Oral 20-40 mg Esophageal and gastrointestin al spastic condition Atropine methonitrate Oral 2.5-10 mg Bronchial asthma and asthmatic bronchitis Ipratropium bromide Inhalation 40-80 μg COPD Propanthelin Oral 15-30 mg Peptic ulcer and gastritis