safe prescribing

Question 1

what are some emergency drugs and their forms

Answer 1

INJECTABLE
- adrenaline
- hydrocortisone (for adrenal crisis, or for anaphylaxis, severe asthma exacerbation)
- antihistamine

INHALATION
- bronchodilator

TABLET
- sublingual nitroglycerin

OTHERS
- water for injection 10mls
- dextrose saline

Question 2

why cant alcoholics take therapeutic doses of paracetamol

Answer 2

because paracetamol is metabolised in liver, and a small amount is converted to toxic metabolite called NAPQI (N acetyl p benzoquinone imine)

normally glutathione in liver neutralizes NAPQI
but alcohol induces liver enzyme CYP2E1, which increases conversion of paracetamol to NAPQI

chronic alcohol use also depletes glutathione stores, making it harder to detoxify NAPQI

Question 3

NSAIDs should be used with caution in which patients

Answer 3

• asthmatics
• peptic ulcer disease
• liver, renal disease
• bleeding
• aspirin
• patients taking prednisolone (corticosteroid causes sodium and water retention and nsaids block prostaglandins which cause kidneys to retain more sodium and water, leading to edema and increased bp)
• ACEI because ACEI dilates efferent arteriole, lowering pressure inside glomerulus, while NSAIDs constrict afferent arteriole, lowering blood entering glomerulus. the double reduction in glomerular filtration pressure will decrease GFR and increase risk of acute kidney injury

Question 4

why are nsaids risky for cvs patients

Answer 4

nsaids inhibit cox enzymes

cox2: reduces prostacyclin (PGI2), which normally prevents platelet aggregation and dilates blood vessels

cox 1 inhibition reduces thromboxane A2, which originally promotes clotting. so technically its supposed to decrease clotting but most nsaids incrase clotting risk because nsaids (except aspirin) have REVERSIBLE COX 1 INHIBITION so duration of platelet effect is short lived… but then the effect on pgi2 (prostacyclin) is significant

i really dont get this
about how nsaids increase clotting risk not because of what they do to txa2 but because they disproportionately reduce prostacyclin, upsetting balance between clot prevention and promotion???

Question 5

when to prescribe gastric cytoprotection with nsaids?

Answer 5

1) patients with known risk eg reflux or hx of gastritis

2) patients with potential risk of GI ulceration and bleeding eg those on SSRI and corticosterodis

3) elderly

Question 6

what drugs interact with omeprazole

Answer 6

omeprazole will

• decrease antiplatelet effect of clopidogrel
• increase effect of warfarin, increase INR

Question 7

what side effects should we look out for when prescirbing PPI

Answer 7

• INcreased incidence of CDAD
• decreased efficacy of clopidogrel
• increased risk of osteoporosis related fractures with prolonged use

Question 8

what analgesics to use and avoid in children

Answer 8

safest = paracetamol syrup
- can also use ibuporfen

avoid aspirin especially for children < 16 years (Reyes syndrome which includes acute encephalopathy and hepatic dysfunction)

avoid codeine and other narcotics due to risk of severe respiratory depression

Question 9

what drugs to avoid for pregnancy

Answer 9

ANALGESICS
- coxibs

Question 10

alternatives to nsaids

Answer 10

1) codeine tabs
- 30mg, 4-6 hourly

2) paracetamol (can use in combination w other stuff?)

3) tramadol (lowkey safer than codeine because its not metabolised to morphine)

4) ultracet
- tramadol 37.5mg
- paracetamol 325mg

Question 11

problems with opioids and which groups to caution in

Answer 11

problems
- opioid abuse and addiction
- resp depression
- constipation
- drowsiness
- hallucinations

caution in
- elderly
- obese patients
- COPD
- OSA
- hepatic/ renal impairment
- CNS patients eg dementia

Question 12

what drugs to avoid for nursing

Answer 12

• codeine because it is metabolised to morphine

Question 13

for antibiotics wise, most oral infections can be treated with?

Answer 13

• amox
• metro
• clinda, doxy

Question 14

ddi and side effects of penicillins

Answer 14

side effect:
- allergy (mostly skin reactions)
- anaphylaxis
- possibility of hallucinations, seizures
- amox clauv is the most common cause of AB induced diarrhoea/ colitis

ddi:
- warfarin: use of penicillin increases PT
- antagonised by bacteriostatic Abs like tetracycline, erythromycin, clindamycin (bc penicillin is bactericidal)

Question 15

what drugs to avoid for cvs patients because they cause arrhythmias

Answer 15

• macrolides
• azoles (cause qt prolongation)

Question 16

ddi of macrolides (especially erythromycin because this is more reactive than azithro)

Answer 16

1) statins
- increase risk of rhabdo

2) theophylline (bronchodilator)

3) warfarin
- increase bleeding risk

4) carbamazepine
- can result in cns toxicity

5) calcium channel blockers
- bradycardia, hypotension

6) antiarrhythmics like amiodarone
- increased QT prolongation

7) potentially fatal in hepatic/renal impairment

Question 17

dosage of metro and its adverse side effects

Answer 17

400mg tds

• metallic taste
• furred tongue
• gi upset
• headache
• CNS: peripheral neuropathy, weakness, insomnia, dizziness