Prescribing errors

Question 1

What are the common enzyme inducers? (Decreased conc.)

Answer 1

PC BRAS

P-Phenytoin
C-Carbamazepine

B-Barbituates
R-Rifampicin
A -Alcohol (Chronic excess)
S- Selphonylureas

Question 2

What are the common enzyme inhibitors? (increases drug conc)

Answer 2

AO DEVICES

A - Allopurinol
O - Omeprazole

D - Disulfiram
E - Erythromycin
V - Valproate
I - Isoniazid
C - Ciprofloxacin
E - Ethanol (acute)
S - Sulphonamides

Question 3

What drugs must you stop before surgery?

Answer 3

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

Question 4

How far before surgery must you stop COCP or HRT?

Answer 4

4 weeks

Question 5

The safe routine for prescribing uses the pneumonic PReSCRIBER: What does it mean?

Answer 5

P - Patient
Re - Allergies (reaction)
S - Signature
C - Contraindications
R - Route
I - Consider IV fluids
B - Thromboprophylaxis
E - Anti-emetics
R - Pain releif

Question 6

Co-amoxiclav and tazocin are part of what drug family?

Answer 6

Penicillins

Question 7

What are four common drug classes where contraindications must be considered?

Answer 7

1) Drugs that increase bleeding
2) Steroids
3) NSAIDS
4) Antihypertensives

Question 8

What are the contraindications for drugs that cause bleeding?

Answer 8

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.

Question 9

What are the contraindications for steroids?

Answer 9

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

Question 10

What are the contraindications for NSAIDS?

Answer 10

NSAID

• No urine
• Systolic dysfunction i.e HF
• Asthma
• Indigestion
• Dyscrasia (clotting abnormalities)

Question 11

What are the contraindications for antihypertensives?

Answer 11

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

Question 12

What are the two situations in which you are prescribing IV fluids?

Answer 12

1. Maintence
2. Replacement

Question 13

What fluid do you normally give?

Answer 13

0.9% saline, a crystalloid unless:

Question 14

When do you give something other than 0.9% NaCl?

Answer 14

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.

Question 15

When replacing fluids how much and how fast?

Answer 15

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.

Question 16

What are the rough predicted fluid losses based on urine output, HR and BP?

Answer 16

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.

Question 17

Whats the general rule about IV fluids?

Answer 17

Never prescribe more than 2L for a sick patient

Question 18

What rate should K be given in IV fluid?

Answer 18

never more than 10mmol/hour

Question 19

What are the common rules for fluid matainence?

Answer 19

• Adults require 3L IV fluids per 24hr, elerly this is 2L
• Electrolytes are sufficient in 1L of 0.9% and 2L of 5% dextrose

Question 20

What is the rate of maintenance fluids?

Answer 20

3L = 24/3 = 8hrly
2L = 24/2 = 12hrly

But in reality you assess the patients needs: urine output, BP, HR, Electrolytes, JVP, oedema, Bladder

Question 21

How is thromboprophylaxis done in hospitals?

Answer 21

LMWH i.e enoxaparin

Question 22

When should metoclopramide be avoided as an antiemetic?

Answer 22

Dopamine antagonist thus:

• Avoid in parkinsons
• Young women as increased risk of dyskinesia

Question 23

What are the antiemetics of choice for someone who is nauseated?

Answer 23

Regular:
- Cylizine (avoid if HF)
- Metoclopramide (if heart failure)
- Ondansetron

Question 24

What are the antiemetics of choice of not nauseated i.e as required? PRN

Answer 24

• Cylizine (avoid if HF)
• Metoclopramide (if heart failure)

Question 25

What happens when you correct an acute AKI with fluid treatment?

Answer 25

At risk for the polyuric phase where output exceeds 200ml/h