Communicating Info and Drug Monitoring Flashcards
Which drugs usually require monitoring?
Drugs with a narrow therapeutic index.
What does “narrow therapeutic index” mean?
Small difference in blood concentration between therapeutic and toxic effects.
Name five drugs that have a narrow therapeutic index.
Digoxin Theophylline Lithium Phenytoin Aminoglycosides
Peripheral neuropathy, gum hypertrophy, ataxia, and nystagmus, are features of toxicity of which drug?
Phenytoin
Visual halos, arrhythmias, nausea, and confusion, are features of toxicity of which drug?
Digoxin
What are some features of gentamycin monitoring?
Patients with severe renal failure or endocarditis may receive divided daily dosing 12-hourly
Gentamycin levels are measured at 6-14h after the last infusion
A normogram is used to determine whether the level is too high.
What is INR?
A ratio of a patient’s prothrombin time compared to the normal population
What is the target INR for patients on warfarin, and an exception?
- 5
3. 5 if recurrent VTE on warfarin or mechanical valve replacement
How is over anti-coagulation managed?
INR<6 reduce warfarin dose
INR 6-8 omit warfarin for 2 days, then reduce dose
INR>8 omit warfarin and give 1-5mg oral Vitamin K.
If a patient is bleeding, on warfarin, how is this managed?
Assuming INR>8
Stop warfarin
5-10mg IV vitamin K or prothrombin complex e.g. Beriplex
At what time of day should ACEIs be administered and why?
Evening due to postural hypotension
Exception - perindopril
What anti-hypertensive drug is used in pregnancy?
Labetalol
Following initiation of an ACEI, what should be monitored?
Renal function
Potassium
1-2 weeks after initiation
Name a drug which increases the risk of endometrial cancer.
Tamoxifen
What are two other adverse effects associated with tamoxifen?
VTE
Increased efficacy of warfarin
What is important information regarding initiation of sulphonylureas, to reduce the risk of hypoglycaemia?
Eat regularly and do not miss meals
Do not double the dose
Take in the morning with breakfast
Do not take at night - increased risk of nocturnal hypo
How often is methotrexate taken, and the route?
Once weekly
PO, or if not tolerated, SC
Name two other folate antagonists.
Trimethoprim
Co-trimoxazole
How often is FBC monitored in patients on methotrexate therapy?
1-2 weekly for first 18 weeks
Then every 2-3 months
Why is folic acid given with methotrexate, and when is it given?
Limits bone marrow toxicity
5mg once weekly 24h later
What advice regarding alcohol should be given to patients taking warfarin?
Ideally, not to drink
If drinking alcohol, it should be moderate and spread out over the week to least impact the INR
How often is INR monitored on warfarin therapy?
Initially weekly
Once stable, monthly
What is a steroid sick day?
If ill, patients should increase the dose of steroid.
What drug should be started with corticosteroids?
Bisphosphonate
Why should patients not stop corticosteroids abruptly?
Risk of Addisonian crisis
How should insulin doses be amended when patients are unwell?
Increased doses
What should diabetic patients do to reduce the risk of lipohypertrophy?
Rotate injection sites
How often is alendronic acid given?
Once weekly
What should be avoided at the time a bisphosphonate is taken?
Calcium salts and food reduces absorption
What are the instructions for taking a bisphosphonate?
Swallow tablet with a full glass of water and remain upright for 30 minutes afterwards
Before starting a statin, what is important to check?
Transaminases, rather than albumin
In what scenario, should creatine kinase be checked at baseline, in patients who are starting a statin?
Increased risk of myopathy
How long after maintenance dosing of phenytoin, should the reported level be within the reference range?
14 days
How long after the last dose of lithium, should the serum concentration be sampled?
12 hours
What is the normal lithium reference range and at what level are toxic effects likely to manifest?
0.4-0.8mmol/L
>1.5mmol/L
How often should serum lithium concentrations be monitored?
Weekly after initiation and after each dose change, until concentrations are stable, then every 3 months
In what scenarios should you stop, or not start methotrexate?
Abnormal LFTs
Low white cells or platelets
Infection
How is olanzapine monitored?
Fasting blood glucose at baseline and at regular intervals thereafter
Baseline ECG if RF
What should be monitored in patients on the COCP?
Blood pressure
For which drug is a baseline CXR, and thyroid function required?
Amiodarone
Which drugs can cause agranulocytosis?
Clozapine
Carbimazole
In monitoring of gentamycin, what action should be taken if the serum concentration is too high? It should be 5-10mg/litre
Reduce the dose, keep the frequency the same
In monitoring of gentamycin, what action should be taken if the trough level is too high (>1mg/litre), but the serum concentration is adequate?
Dosing interval should be increased
Dose remains the same
Which drugs significantly reduce lithium excretion?
ACEI
Diuretics
NSAIDs
Which type of diuretic is safest for use in patients taking lithium?
Loop
In up or down titration of a drug, what increment should be used?
The smallest possible - use BNF as a guide.
Unless toxicity is suspected.
When aminophylline is prescribed in acute asthma attack, how is its effect monitored?
Improved oxygen saturations
How is pneumonia treatment monitored?
Improvement in oxygen saturations, ABG, or RR.
Consolidation on a CXR may take up to 6 weeks
How is DKA response to treatment monitored?
Serum ketones
How is acute HF response to treatment with furosemide measured?
Weights
Is a small rise in creatinine after initiation with ACEI normal?
Yes, repeat U&Es a week later
In steroid induced hyperglycaemia, how Is insulin treatment changed?
Increase usual insulin dose by 10%
What should INR be before surgery in patients on warfarin?
<1.5
If >1.5, give PO vitamin K
