Basic principles of prescribing

Question 1

Every drug prescription must be (LUACWSISD) + If PRN (IMf)

Answer 1

1. Legible
2. Unambiguous
3. Approved name (e.g. salbutamol, not ventolin)
4. in Capitals
5. Without abbreviations
6. Signed
7. Indication (+ stop and review date)
8. Duration

If PRN:
1. Indication
2. Maximum frequency

Question 2

Exceptions when trade names should be used

Answer 2

1. Tacrolimus preparations (e.g Adoport, Advagraf, Dailiport, Modigraf, Prograf and Envarsus)
2. DO NOT WRITE TAZOCIN INSTEAD OF PIPERACILLIN WITH TAZOBACTAM (TAZOCIN masks the -cillin suffix, may be missed in penicillin allergies)

Question 3

What term is used to define the effect of drugs on the body?

Answer 3

Pharmacodynamics

Question 4

What term is used to define the effect of the body on drugs?

Answer 4

Pharmacokinetics

Question 5

1. What is the enzyme system by which most drugs are converted into inactive metabolites?
2. Where is it located?

Answer 5

1. Cytochrome P450
2. In the liver

Question 5

1. What is the enzyme system by which most drugs are converted into inactive metabolites?
2. Where is it located?

Answer 5

1. Cytochrome P450
2. In the liver

Question 6

Enzyme inducers
1. Most common (PC BRAS)
2. What do they do and what is the effect on drug concentrations
3. What action would you consider taking re drug dosage, in light of the previous question

Answer 6

1. PC BRAS

Phenytoin
Carbamazepine
Barbiturates (-barbital)
Rifampicin
Alcohol (chronic excess)
Sulphonyureas (anti-diabetics ending in -ide e.g. glipizide)

2. Increase enzyme activity, therefore decreasing drug concentration
3. Consider increasing the dose of the drug that is being affected by the inducer

Question 7

Enzyme inibitors
1. Most common (AODEVICES)
2. What do they do and what is the effect on drug concentrations
3. What action would you consider taking re drug dosage, in light of the previous question

Answer 7

1. AO DEVICES
   Allopurinol
   Omeprazole

Disulfiram
Erythromycin
Valproate
Isoniazid
Ciprofloxacin
Ethanol
Sulphonamides (e.g. sulphadiazinem, sulfamethoxazole)

2. Decrease enzyme activity, therefore increasing drug concentration
3. Consider decreasing the dose of the drug that is being affected by the inhibitor

Question 8

Drugs to stop before surgery (I LACK OP)

Answer 8

Insulin
Lithium
Anticoagulation
COCP/HRT
K-sparing diuretics
Oral hypoglycaemics –> metformin causes lactic acidosis, others may cause hypos –> switch to sliding scale with regular BM monitoring
Perindopril + other ACEi