Effect of a P450 inducer?
Increase metabolism of P450, therefore drug exerts less of an effect
Effect of a P450 inhibitor?
Reduced metabolism of P450, therefore drug exerts more of an effect.
Examples of P450 Inducers ?
Increased enzyme activity, decreased drug concentration
Examples of P450 inhibitors?
AODEVICES
Drugs to stop before surgery - COCP?
4 weeks before surgery
Drugs to stop before surgery
- Lithium
Day before
Drugs to stop before surgery
- Potassium sparing diuretics and ACEi?
Day of surgery
Drugs to stop before surgery
Generally Warfarin is stopped and bridged with LMWH.
Drugs to stop before surgery -
Oral hypoglycaemic drugs and insulin?
Patient is NBM before surgery.
Metformin should be stopped because it will cause lactic acidosis.
In all cases - a sliding scale should be started instead - hourly blood glucose monitoring and adjust hourly dose.
Mnemonic for drugs to stop before surgery?
I LACK OP
Management of long-term corticosteroids (pred) before surgery?
Increase steroid requirement
At IOA, patient should be given IV steroids.
Drugs to stop for a patient with haemoptysis?
Aspirin (Antiplatelet)
Enoxaparin (LMWH)
Drugs to stop patient is hyperkalaemic?
ACEi
IV fluid with K should be stopped.
Also patient is receiving 6g of paracetamol so should be stopped.
Common pitfalls for prescribing?
Ensuring we have correct patient’s prescription/drug chart
Noticing and recording allergies
SIgning the front of the chart.
Considering contraindications for each drug we prescribe.
Consider the route for each drug we prescribe
Consider the need for IV fluids.
Consider need for thromboprophylaxis
Consider need for antiemetics
Consider need for pain relief.
What is the PReSCRIBER mnemonic?
Patient Details Reaction Sign the front of the chart check for Contraindications to each drug Prescribe Intravenous fluids if needed Prescribe Blood clot prophylaxis if needed Prescribe antiEmetic if needed Prescribe pain Relief if needed.
When working on a new chart what must you write?
3 piece of patient identifying information on the front
Reactions for drug charts?
Check allergy box to include any drug reaction
Don’t forget that co-amoxiclav and Tazocin both contain penicillin.
Contraindications in drug charts? - Bleeding
Consider whether it is contraindicated.
Drugs that increase bleeding (aspirin, heparin and warfarin). Should not be given to those risk of bleeding (liver disease).
Prophylactic heparin is contraindicated in acute stroke - risk of bleeding.
Be wary that enzyme inhibitors AODEVICES can increase PT and INR.
Contraindications for drug chart - Steroids?
Side effects -
Contraindications for rugs - NSAIDS?
Aspirin, whilst not technically an NSAID. It is not contraindicated in renal or heart failure.
Antihypertensives - SE?
Hypotension that may result from all groups of antihypertensives.
Bradycardia = beta blockers + CCBs .
Electrolyte disturbances with ACE and diuretics.
Individual drug classes have specific side effects
- ACEi = Dry cough
- Beta-blockers = wheeze in asthmatics
- CCB = Peripheral oedema and flushing
- Diuretics = renal failure. Loop diuretics can also cause gout.
Spironolactone causes
Route for patients?
if vomiting = antiemetics should be given by non-oral routes = IV/IM/SC
E.g Cycline 50mg 8hrly IV or PO
Metoclopramide 10mg 8 hrly.
If a patient is nil by mouth should still receive oral medication.
When are IV fluids prescribed?
As replacement for dehydrated/acutely unwell patient
As maintenance in patient who is nil by mouth.
Which fluid to prescribe?