S14) Clinical Influences on Prescribing Flashcards
How might one classify poisoning?
- Intended – alcohol, illicit drugs, deliberate self harm
- Unintended – iatrogenic (older), paracetamol (younger)
Identify five common UK poisons
- Paracetamol
- Hypnotics (diazepam, zoplicone)
- Salicylates
- Ecstasy
- Opiates
How does an overdosed patient present?
- May be obvious
- Might be concealed
- Coma
What are the clinical findings of patients who have overdosed?
- Alcohol/solvents on breath
- Needle track marks
- Blisters (barbiturates)
What are the neurological signs of overdosed patients?
- UMN signs (anti-cholinergics) – hyperreflexia, hypertonia
- Coma (many) – decerbrate/decorticate posturing
- Dystonic movements (metoclopramide)
Indicate the various effects different drugs have on the pupils when taken in excessive amounts
- Dilated pupils (mydriasis) – anti-cholinergics (TCAs), sympathomimetics (amphetamines), blindness (quinine, ethanol)
- Constricted pupils (miosis) – opiates, nerve agents (VX)
Indicate the various effects different drugs have on ventilation when taken in excessive amounts
- Hypoventilation – opiates, CO poisoning
- Hyperventilation – salicylates
Indicate which drugs are responsible for the following blood gas findings when taken in excessive amounts:
- Metabolic acidosis
- Respiratory alkalosis
- Hypokalaemia
- Hyponatraemia
- Hypoglycaemia
- Metabolic acidosis – ethanol
- Respiratory alkalosis – salicylates
- Hypokalaemia – β agonists
- Hyponatraemia – ectasy
- Hypoglycaemia – insulin, alcohol
Outline the general management for a patient presenting with a drug overdose
- ABCDE
- History (incl. collateral history)
- Examination findings
- Supportive care
- Appropriate antidotes (when indicated)
Identify some general investigations for patients with a drug overdose
- Blood
- Urine
- ECG – conduction delays, tachyarrhythmias
Identify some specific investigations for patients with a drug overdose
- Paracetamol
- Salicylates
- Other toxicology
Describe normal paracetamol metabolism
In three steps, describe paracetamol metabolism after substantial overdose as well as its treatment
⇒ Conjugation of NAPQI is saturated
⇒ Increasing toxic levels of NAPQI
⇒ Thus, treatment is to replace Glutathione i.e. N-acetylcysteine (Parvolex)
Identify six complications from paracetamol overdose and/or its treatment
- Violence
- Hypothermia
- Hyperthermia
- Convulsions
- Rhabdomyolysis
- Urinary retention
What are the influences on patient response to drug therapy?
- Genetics (20-95%)
- Age
- Organ Function
- Drug Interactions
- Nature of disease
