Toxidromes

Question 1

Mechanism of action of atropine and hyoscyamine

Answer 1

Peripheral: antagonize the muscarinic action of acetylcholine.
Central: stimulation followed by depression of central nervous system.

Question 2

mechanism of action of hyoscine

Answer 2

Peripheral action is weaker & Central action is depression of central nervous system without initial stimulation.

Question 3

anticholinergic cause depression of
central nervous system without initial stimulation.

Answer 3

Hyoscine

Question 4

Mechanism of action of antihistamincs

Answer 4

• .Antagonize effects of histamine on H1 receptor.
• Anticholinergic action (except second-generation).
• Large diphenhydramine overdose: Prolongation of QRS (sodium channel blockade).

Question 5

MOA of tricyclic antidepressants

Answer 5

1. neurotransmitter reuptake inhibition: NE, Dopamine, Serotonin
2. Receptor blockade: cholinergic, alpha adrenergic, histaminic receptor
3. cardiovascular effects:
   Myocardial effects: Direct Quinidine like effect (block sodium channels) conduction defects and arrhythmias
   Hypotension: direct myocardial depression, peripheral vasodilation, and increased capillary permeability

Question 6

cause dirct quinidine like effect which blocks sodium channels causing arrhythmias and conduction defects

Answer 6

TCA
imipramine
amitriptyline

Question 7

anticholinergic that blocks dopamine receptors

Answer 7

phenothiazine (chloropromazine)

Question 7

mechanism of action of Phenothiazine

Answer 7

• receptor blockade: cholinergic, alpha adrenergic, Histamine, and dopamine receptor
• Blockade of Dopamine receptors — Extrapyramidal
  Manifestations & increased Prolactin (amenorrhea
  galactorrhea syndrome).
• CVS effects: myocardial defects and Hypotension
• CNS effects: Depression of:
• Cerebral cortex —- Coma and Seizures may occur.
• Respiratory center — Respiratory failure.
• Chemoreceptor trigger zone (CTZ) — Antiemetic action.
• Heat regulatory center (HRC) — Hyperthermia or
  Hypothermia

Question 8

effect of phenothiazine on CNS

Answer 8

Depression of:
- Cerebral cortex —- Coma and Seizures may occur.
- Respiratory center — Respiratory failure.
- Chemoreceptor trigger zone (CTZ) — Antiemetic action.
- Heat regulatory center (HRC) — Hyperthermia or
Hypothermia

Question 9

causes rhabdomyolysis

Answer 9

anticholinergics (atropine, diphenhydramine, TCA:imi&ami, phenothiazine)

Question 10

causes torsade’s de pointe

Answer 10

TCA and phenothiazine
not in diphenhydramine

Question 11

physostigmine is contraindicated in

Answer 11

wide QRS complex, bradycardia, asthma
and bowel or bladder obstruction.

Question 11

investigation of anticholinergic poisoning

Answer 11

1. Routine lab investigations
2. CPK: Elevated (in case of rhabdomyolysis).
3. Toxicological screening.
4. ECG & continuous cardiac monitoring.
5. X-ray abdomen: phenothiazine tablets are radio-opaque.

Question 11

mechanism of physostigmine

Answer 11

• it reverses the peripheral & central anticholinergic effects.
• It is indicated in severe cases
• it is should given under cardiac monitoring

Question 11

sodium bicarbonate is indicated in

Answer 11

conduction defects
arrhythmias
metabolic acidosis

Question 11

antidote of atropine and antihistamine

Answer 11

Physostigmine
- lt reverses the peripheral & central anticholinergic effects.
- Itis indicated in severe cases.
- It should be given under cardiac monitoring & should not be given as a constant infusion for a long time.
- It is contraindicated with wide QRS complex, bradycardia, asthma and bowel or bladder obstruction.

Question 11

mechanism of sodium bicarbonate in antidoting TCA

Answer 11

alkalinization
increase plasma sodium

Question 11

symptomatic treatment of anticholinergic manifestation

Answer 11

Urinary catheterization.
Hyperthermia: cold foments.

Question 11

symptomatic treatment of CNS manifestation

Answer 11

Seizures — diazepam.
Coma — Care of the coma

Question 11

symptomatic treatment of arrhythmia caused by TCA and phenothiazine

Answer 11

sodium bicarbonate

Question 11

symptomatic treatment of torsade de pointes

Answer 11

Hemodynamically unstable patients — _ electrical
cardioversion.
Hemodynamically stable patients — MgSO4 & correct electrolyte abnormalities.

Question 11

symptomatic treatment of hypotension

Answer 11

Normal saline + vasopressor agent.

Question 11

S treatment of rhabdomyolysis

Answer 11

alkalinization of urine (Na bicarbonate)
diuretics

Question 11

S treatment of Neuroleptic malignant syndrome

Answer 11

Dantrolene sodium and bromocriptine

Question 11

administration of physostgmine with TCA

Answer 11

induce fatal bradyarrhythmias

Question 12

clinical presentation of amphetamine and cocaine poisoning on CVS

Answer 12

• Tachyarrhythmia, Hypertension, Cerebral haemorrhage.
• Cardiogenic shock and circulatory collapse.
• -In cocaine: Wide QRS ventricular dysrhythmias, coronary artery spasm and myocardial infarction may occur.

Question 13

clinical presentation of amphetamine and cocaine poisoning on Respiratory

Answer 13

Respiratory alkalosis,
pulmonary hypertension
pulmonary oedema

Question 13

Diuresis, dialysis & hemoperfusion are mostly ineffective in elimination of anticholinergic drugs due to:

Answer 13

• Large volume of distribution.
• Tight binding of the drug to plasma proteins (except for atropine).

Question 14

mechanism of action of amphetamine & cocaine

Answer 14

• Sympathomimetic and C.N.S stimulant by increasing catecholamines (epinephrine, norepinephrine & dopamine).
• Local anaesthetic (in Cocaine only): Blocks the sodium channels.

Question 15

clinical presentation of amphetamine and cocaine poisoning on CNS

Answer 15

CNS stimulation followed by depression
Stimulation:
Euphoria, hyperreflexia, tremors, and convulsions which may cause rhabdomyolysis and metabolic acidosis
serotonin syndrome in severe amphetamine poisoning
hyperthermia
Depression:
drwosiness, confusion, cyanosis, coma and death from central asphyxia

Question 16

clinical presentation of amphetamine and cocaine poisoning on renal

Answer 16

Kidney failure
Shock and decreased renal perfusion
Rhabdomyolysis and myoglobinuria.

Question 17

cause of the necrotic ulcers ‘‘coke burns’’

Answer 17

Accidental subcutaneous injection of cocaine

Question 18

Hyperthermia caused by amphetamine due to:

Answer 18

¢ Heat gain (increased muscle contractility).
¢ Disturbances of heat regulatory centre (HRC).
¢ Decreased heat loss due to vasoconstriction (V.C.) in cocaine.

Question 18

cause of death result from amphetamine poisoning

Answer 18

• Hyperthermia -—> rhabdomyolysis (myoglobinuric renal failure), coagulopathy, and multiple organ failure.
• Central asphyxia.
• Circulatory collapse.

Question 18

causes amenorrhea and galactorrhea syndrome

Answer 18

phenothaizine

Question 18

urinary benzoylecogonine related to

Answer 18

cocaine, detected up to 3 days

Question 18

toxidrome causes respiratory alkalosis

Answer 18

amphetamine and cocaine