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Therapeutic Drug Monitoring - Coggle Diagram
Therapeutic Drug Monitoring
Therapeutic Window
Expresses a range of concentrations in which the likelihood of efficacy is high and the probability of adverse effects is low
Drugs Needing Monitoring
Phenytoin
Lithium
Theophylline
Aminoglycosides
Gentamicin
Tobramycin
Netilmicin
Amikacin
Antiarrhyhmics
Digoxin
Quinidine
Lignocaine
Fleacanide
Antibiotics
Vancomycin
Teicoplanin
Iron
Salicylate
Paraquat
Indications
Improve drug
Efficacy
Ensure drug
Compliance
Avoid drug
Interactions
Reduce drug
Adverse effects
Goal
Optimise a pts clinical outcome by managing their medication regimen with assistance of measured concentration
Pharmacokinetics
Steady state
Concentration of a drug when the rate if drug elimination = rate of administration, assuming complete bioavailibility
Takes 5 t1/2 to reach steady state
Half life
Time it takes for the plasma concentration
to fall by 50%
Requesting Drug Conc
Toxicity suspected
Toxic concentrations
Amikacin
Lack of response
Suptherapeutic concentrations
Carbamazepine
Assessment of compliance with therapy
Digoxin
Assess therapy following change in dose
Phenytoin - zero order
Change in clinical state of pt
Lithium, phenytoin
Potential drug interaction due to a change in comedication
Theophylline + Ciprofloxacin
Manifestations of toxicity and disease state are similar
Digoxin
Criteria for Drug Monitoring
There should be a relationship between
plasma conc
and
therapeutic effec
Substantial
interpatient **
variability** in drug disposition is evident
It should be
difficult to monitor
intended or uninteded effects of the drug
4.
Low therapeutic index
of the drug
Antiepileptics
Theophylline
Indication
Prophylaxis of bronchospasm
Asthma
COPD
ADs
Seizures
Cardiac arrhythmias
Therapeutic Range
10-20 mg/L
55 -110 μmol/L
T1/2
10 hrs
Sensitivity
Neurological disease
Cardiovascular disease
Extremes of age
Poisoning
more than 100 mg/kg
Activated charcoal
Take conc on admissiona and measure at regular intervals
Lithium
Indication
Prophylaxis
Mania
Manic-depressive illness
Recurrent depression
Poisoning
CNS symptoms or concentrations greater than 1.5
Adverse Effects
1.5 - 1.2 mmol/L
Tremor
Dysarthria
Hyperreflexia
2.5 3.0 mmol/L
Confusion
Ataxia
Myoclonic movements
3.0 mmol/L
Delirium
Coma
Seizures
Treatment
Haemodialysis
Aminoglycosides
Examples
streptomycin
Gentamicin
Amikacin
Indications
Aerobic gram negative bacetria
Pharmacokinetics
Polycations
Poor absoprtion
Inadequate CSF conc
Rapid renal elimination
Adverse Effects
Ototoxicity
Nephrotoxicity
Vancomycin
Indication
Broad spectrum gram positive bacteria
Penetration
CSF
Bile
Pleural
Pericardial
Synovial
Ascitic fluids
Adverse Effects
Infusion reactions due to histamine - Red man syndrome
Nephrotoxicity
Ototoxicity
Overdose - Paracetamol
Concentrations above the treatment line should recieve N-acytlcysteine
Higher Risk of Hepatotoxicity
Enzyme inducers
Phenytoin
Alcohol
Rifampicin
Carbamazepine
Adverse Effects
Severe hepatocellular necrosis
