Muscarinic antagonists:- Naturally occurring atropine & hyoscine, homatropine

Quaternary ammonium comp:- atropine methonitrate, propantheline. Pirenzepine, selective M1 receptor antagonist

Pharmacokinetic aspects:- hyoscine absorbed transdermally. 4º amines do not cross the BBB Metabolism & excretion:-

Mechanism:- reversible blockade of Ach at muscarinic receptors.

Organ system effects:- CNS:- atropine at clinical dose, initial stimulation followed by slower longer –lasting sedative effect, Hyoscine  sedative effect

2-Eye:- pupillae constrictor  mydriasis, cilliary muscle [cycloplagia]. 3-  lachrymal secretion.

3-Cardiovascular system:- SA node & atrium. Atropine on isolated heart  tachycardia, Intact animals, initial bradycardia followed by tachycardia Skeletal muscle blood vessels → ↓vasodilatation.

4-Respiratory system:- Atropine  bronchodilation &  of secretion 5-GIT:-  motility &secretion. salivary glands, gastric secretion. Pancreatic & intestinal secretion.

6-Genitourinary tract:- uriters, bladder wall, 7-Sweat glands:- in children modest doses  ”atropine fever”

Quiz? Your pharmacology laboratory has been given a new compound for screening. It is found to increase heart rate, dilate the pupil, reduce glandular secretions and decrease gastrointestinal motility. You would classify this compound as a(an):- 1. alpha agonist 2. antimuscarinic 3. beta agonist 4. parasympathomimetic.

A-CNS:- a- Parkinsonism:- benzhexol, benztropine

b-Motion sickness:- hyoscine

B-Ophthalmic disorders:- ophthalmoscope examination of retina

Quiz? Mydriasis without loss of accommodation:- atropine sympathomimetic Scopolamine Tropicamide cyclopentolate

C-GIT:- i- gastric hypermotility & ulcer. Pirenzepine ii-Facilitate endoscopy

iii-Irritable bowel syndrome, colonic diverticular disease e.g. dicyclomine iv-Traveler's diarrhoea with opioid [diphenoxylate] v-biliary & renal colic.

urinary urgency caused by minor inflammatory bladder disorders

E-Cardiovascula effects:- pain of myocardial infarction]  depression of SA, AV node [sinus bradycardia ]

F-Respiratory disorders:- pre- operative medication when anaesthetic  secretion & laryngospasm, Hyoscine  amnesia,

Ipratropium, inhalation, bronchial asthma, chronic obstructive pulmonary disease (COPD)

Hyperhydrosis

F-Cholinergic poisoning:- Cholinesterase inhibitors “insecticides”. Mushroom poisoning.

Quiz? Current primary therapeutic rationale for using anticholinergic preoperative medication:- sedation antisialagogue effects both neither

Quiz? Preferred anticholinergic drug when sedation is the principal objective, preoperatively:- atropine glycopyrrolate hyoscine

Quiz? Anticholinergic drug most likely to be used clinically to promote bronchodilation:- IV atropine aerosolized atropine aerosolized ipratropium bromide scopolamine

Dry mouth, mydriasis, tachycardia, hot flushed skin, agitation, delirium,  body temperature, blurred vision, confusion, constipation, urinary retention.

Reversed by physostigmine. Quaternary amine poisoning is reversed by quaternary CI, hypotension reversed by sympathomimetic drugs

Contra- indications:- Glaucoma, elderly people with prostatic hypertrophy tachycardias secondary to thyrotoxicosis or cardiac insufficiency, GI obstructive disease, paralytic ileus, Non selective M blockers →ulcer

Quiz? Which of the following is not a side effect of the cholinoreceptor blocker (Atropine)? A. Increased pulse B. Urinary retention C. Bronchospasm D. Mydriasis

Quiz? A patient is brought into the emergency room. Upon examination you find the following: a high fever, rapid pulse, no bowel sounds and dilated pupils that do not respond to light. His lungs are clear. His face is flushed and his skin is dry. He is confused, disorientated and reports 'seeing monsters'. Based on these symptoms, you suspect he has been 'poisoned'. Which of the following, is the MOST obvious and BEST choice as an antidote? A. Atropine sulfate B. Physostigmine C. Neostigimine D. Acetylcholine

Quiz? You are working in the post anesthesia care unit of a hospital. You have just received a patient back from surgery and you are monitoring his status. Knowing that the patient has received atropine, which of the following statements/observations is UNEXPECTED? A. The patient is complaining of extreme thirst. B. The patient complains he is unable to clearly see the clock located just across from him. C. The patient's heart rate is elevated. D. The patient reports he has cramping and diarrhea.

A 55-year-old man was found unconscious by his wife in the greenhouse behind their home. During the past week, he had been complaining of abdominal discomfort and frequent stools. He had no history of mental illness or of alcohol or tobacco use, and he was not taking any medication. He and his wife operated a small flower shop, and he was an enthusiastic home gardener. Upon arrival at the emergency room, the patient was unconscious, salivating profusely, and breathing shallowly. His skin was warm and moist. Blood pressure was 140/90 mm Hg, pulse 72/min and regular, respirations 30/min, and temperature normal.

There was no evidence of trauma. Both pupils were constricted and did not respond to light. Auscultation of the chest revealed moderate wheezing. The extremities showed subcutaneous muscle fasciculations at the time of admission. These disappeared during the course of the examination, but muscle tone decreased and breathing became shallower during this time. The neurologic examination revealed coma with no response to painful stimuli, no localizing signs, and no abnormal reflexes.

Q1 What are the possible toxicologic causes of the patient's signs and symptoms?

Q2? What immediate nonpharmacologic steps must be taken?

Q3? What drugs may be considered for the treatment of this patient? What are the risks and benefits of their use?