Prescribing errors Flashcards
What are the common enzyme inducers? (Decreased conc.)
PC BRAS
P-Phenytoin
C-Carbamazepine
B-Barbituates
R-Rifampicin
A -Alcohol (Chronic excess)
S- Selphonylureas
What are the common enzyme inhibitors? (increases drug conc)
AO DEVICES
A - Allopurinol
O - Omeprazole
D - Disulfiram
E - Erythromycin
V - Valproate
I - Isoniazid
C - Ciprofloxacin
E - Ethanol (acute)
S - Sulphonamides
What drugs must you stop before surgery?
I LACK OP
I - Insulin
L - Lithium
A - Anticoagulants / Antiplatelets
C - COCP / HRT
K - K sparking diuretics
O - Oral hypoglycaemicas
P - Perindopril and other ace inhibitors
How far before surgery must you stop COCP or HRT?
4 weeks
The safe routine for prescribing uses the pneumonic PReSCRIBER: What does it mean?
P - Patient
Re - Allergies (reaction)
S - Signature
C - Contraindications
R - Route
I - Consider IV fluids
B - Thromboprophylaxis
E - Anti-emetics
R - Pain releif
Co-amoxiclav and tazocin are part of what drug family?
Penicillins
What are four common drug classes where contraindications must be considered?
1) Drugs that increase bleeding
2) Steroids
3) NSAIDS
4) Antihypertensives
What are the contraindications for drugs that cause bleeding?
Drugs that cause bleeding: Antiplatelets or anticoagulants
Do not give if or suspected of bleeding. Increased risk of bleeding i.e liver disease with raise PT.
What are the contraindications for steroids?
Side effects thus more loosely C/I
STEROIDS
- Stomach ulcers
- Thin skin
- Oedema
- Right and Left HF
- Osteoporosis
- Infection
- Diabets (causes hyperglycemia and can cause DB)
- Cushings syndrome
What are the contraindications for NSAIDS?
NSAID
- No urine
- Systolic dysfunction i.e HF
- Asthma
- Indigestion
- Dyscrasia (clotting abnormalities)
What are the contraindications for antihypertensives?
1) Hypotension.
2) Bradycardia ( beta blockers and some CCB)
3) Electrolyte disturbances (ACE and diuretics)
Aka, mechanism is important
1) ACE = dry cough
2) Beta blockers - Wheeze and worsen acute HF
3) CCB cause peripehral oedema and flushing
4) Diuretics can cause renal failure. Thiazide diuretics can cause gout. K sparing duretics i.e spironolactone can cause gynocomastia
What are the two situations in which you are prescribing IV fluids?
- Maintence
- Replacement
What fluid do you normally give?
0.9% saline, a crystalloid unless:
When do you give something other than 0.9% NaCl?
1) Hypernatraemia or hypoglycaemic. Give 5% dextrose instead
2) Ascites. Give human-albumin soution instead. (0.9% would worsen things)
3) Shocked from bleeding, give blood transfusion OR crystalloid if bllood not available.
When replacing fluids how much and how fast?
Assess BP, HR and urine output
- If tachycardic or hypotensive give 500mL BOLUS (250 if HF hx), then reassess patient. HR, BP, and urine output. - no response use next IV bag. (colloid is no longer convention)
- If oliguric (no obstruction) 1L over 2-4hrs and then reassess.
What are the rough predicted fluid losses based on urine output, HR and BP?
NB: Reduced urine output (<30mL/h, anuric 0mL/h) = 500+mL fluid depletion.
Decreased urine output + Tachycardia = 1L fluid loss
Reduced urine, tachycardia + shocked = 2L fluid depletion.
Whats the general rule about IV fluids?
Never prescribe more than 2L for a sick patient
What rate should K be given in IV fluid?
never more than 10mmol/hour
What are the common rules for fluid matainence?
- Adults require 3L IV fluids per 24hr, elerly this is 2L
- Electrolytes are sufficient in 1L of 0.9% and 2L of 5% dextrose
What is the rate of maintenance fluids?
3L = 24/3 = 8hrly
2L = 24/2 = 12hrly
But in reality you assess the patients needs: urine output, BP, HR, Electrolytes, JVP, oedema, Bladder
How is thromboprophylaxis done in hospitals?
LMWH i.e enoxaparin
When should metoclopramide be avoided as an antiemetic?
Dopamine antagonist thus:
- Avoid in parkinsons
- Young women as increased risk of dyskinesia
What are the antiemetics of choice for someone who is nauseated?
Regular:
- Cylizine (avoid if HF)
- Metoclopramide (if heart failure)
- Ondansetron
What are the antiemetics of choice of not nauseated i.e as required? PRN
- Cylizine (avoid if HF)
- Metoclopramide (if heart failure)
What happens when you correct an acute AKI with fluid treatment?
At risk for the polyuric phase where output exceeds 200ml/h