therapeutic drug monitoring

what does narrow therapeutic index mean

difference between effective dose and toxic dose is very small

example of a drug with narrow therapeutic index

phenytoin

what is therapeutic drug monitoring

measuring specific drug concs in patients at regular intervals

what is the importance of TDM in patient care

enables medicines to be personlised cos not every patient metabolises or responds to drugs in the same way

what is TDM used for

to avoid underdosing and toxicity

define high risk medicines

medicines that have high risk of causing harm or injury if they are misused or used in error

true or false: error rates with high risk meds are higher than normal meds

false - they are the same. but when the errors occur, the consequences are more significant

examples of high risk meds

• methotrexate

• lithium

• anticoagulants

• antibiotics

• injectable sedatives

• opioids

• antipsychotics

• insulin

• infusion fluids

examples of drugs with narrow therapeutic range

• carbamazepine

• digoxin

• gentamicin

• lithium

• phenytoin

• theophylline

• vancomycin

• warfarin

role of the pharmacist within TDM

• ensure safety

• ensure efficacy (that the drug is doing what is needs to do)

• ensure quality (standard of care using NICE guidelines and following legislation)

• supporting patients

why monitor therapy

• ensure efficacy

• ensure safety

• minimize toxicity

what are the cardiovascular monitoring conditions

• heart rate

• blood pressure

• chest pain

• oedema

• shortness of breath

• weight loss/gain (aligned with oedema)

• exercise tolerance

• troponin

• creatine kinase

monitoring conditions for infection

• temp

• white blood cell count

• microscopy, culture and sensitivites

• symptoms

• CRP

monitoring conditions for diabetes

• blood glucose

• HbA_1c

• insulin dose

• hypo/hyperglycaemia

• macrovascular complications (CVD)

• microvascular complications

  • eye disease

  • neuropathy

  • renal disease

how to monitor pain

• pain score

• analgesic use

• respiration rate

pain is subjective so use a universal pain score

how to monitor respiratory

• shortness of breath

• PEFR (peak respiratory flow rate - asthma)

• FEV1 - forced expiratory volume - COPD)

• respiratory rate

• reliever use

• FVC - first vital capacity - COPD specific

monitoring patient that are taking different conditions

what else to consider if patient is on multiple drugs e.g. amiodarone and theophylline

for example amiodarone is an inhibitor of cytochrome P450 so it inhibits the metabolism of certain drugs

smoking increases clearance of theophylline as smoking is induction at cytochrome P450