TDM and Toxicology Flashcards

1
Q

What drugs need monitoring

A

Drugs that are always measured
-Lithium -Antibiotics -Vancomycin -Aminoglycosides -Immunosuppresants -Cyclosporin -Tacroliumus

Drugs that are occasionally measured

  • Digoxin -Theophylline (obstructive airway disease)
  • Anti-epileptics- phenytoin, carbamazepine, sodium valproate
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2
Q

What tests do we use to measure these drugs

Warfarin 
Diuretics, ACE inhibit, NSAIDs 
Spironolactone 
Statin 
Penicillamine
A
Warfarin- INR 
Diuretics and Ace inhibit- Renal U&E and potassium 
NSAIDs- renal U&E 
Spironolactone- Potassium 
Statin - LFTs 
Penicillamine- urine protein
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3
Q

What is lithium used for and why/ how is it monitored

A
  • Bipolar disorder treatment
  • Measure sodium for diabetes insipidus
  • Measure renal function and TFTs
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4
Q

What antibiotics need monitored and how/ why are they monitored

A
  • Need to measure ahminoglycosides and vancomycin
  • Avoid toxicity- renal and auditory nerve
  • Tailor dose to ensue therapeutic effect
  • Peak and trough levels
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5
Q

Why is drug monitoring important in immunosuppressants

A
  • Enough of a dose to prevent organ rejection but also prevent toxicity
  • Immunosuppresants toxic to kidneys so monitor renal function
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6
Q

What is the initial assessment steps for a patient with an overdose

A
  • Assess consciousness - head injury act
  • Resp effort and cyanosis
  • Cardio exam- pulse and BP
  • Neuro exam
  • Pupil size and reactivity- opiates
  • Suicide assessment
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7
Q

What are the main self harm drugs

A
  • Benzodiazepines
  • Tricycylic antidepressants
  • Paracetamol
  • Aspirin
  • Alcohol
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8
Q

Discuss the process of paracetamol toxicity and how it is managed

A
  • Paracetamol converted to toxic metabolite N-acetyle-p-benzoquinonmine (NAPQI) which is normally inactivated by glutathione
  • Depleated glutathione in overdose causes NAPQI to bind with sulphur groups on liver membranes causing liver cell necrosis

-Poisoning is 1st asymptomatic, liver failure occurs 72-96 hrs after and may need transplant

Management- measure paracetamol levels at presentation

  • Level after 4 hrs- determine if treatment is needed
  • Give acetylecysteine (replaces glutathione)
  • Give within 8 hrs of overdose
  • Increased risk in alcohol abuse, liver enzyme inducing drugs (phenytoin) they will metabolise paracetamol quicker
  • Measure INR and creatin9ne
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9
Q

What are the symptoms of aspirin overdose and how is it managed

A
  • Vomiting, sweating, tinnitus , blurred vision, early resp alkalosis then metabolic acidosis later
  • Renal failure

Management:
Mild/moderate levels (<600mg/l) oral or IV rehydration and K+ supplements
Severe levels need specific elimination therapy
1. Activated oral charcoal (50g/4hrs) - prevents salicylate absorption
2. Alkalisation 1L 1.26 NaHCO3 over 2 hrs - repeated to keep urine pH >7.5
3. Haemodialysis- levels >1000mg in persistent acidosis or loss of conscious

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10
Q

What are the features and management of ethanol overdose

A
  • Despressed consciousness and hypoglycaemia (esp in children)
  • Supportive treatment- monitor fluids and glucose
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11
Q

What is the important thing about Benzodiazepine and tricyclic antidepressant overdose

A
  • No specific treatment and can’t tell exact levels in overdose- only detects if they are present in blood
  • Wont indicate if dosage was regular or excessive
  • If resp rate falls with benzodiazepines you can give flumazenil
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12
Q

What is the management for lead and iron overdose

A

Lead= an occupational exposure
-Levels are monitored <4mmol/L -Abdo pain, anaemia, peripheral neuropathy, bone marrow suppression
Treatment: Remove source, chelation therapy, ca EDTA, penicillamine

Iron- emergency

  • Abdo pain (gastric erosion) -Nausea -Hypotension -Hepatic injury
  • Measure iron levels -Treatment= Chelation with desferrioxamine
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