Simple analgesics

Question 1

Tell me about paracetamol?

Answer 1

Paracetamol is an NSAID that is used for analgesia and its antipyretic properties.

Physical: para-aminophenol
- CCS of 10mg/ml and 500mg tablets/capsules sometimes combined with codeine etc.
- cupboard
- 1g 6h or kids 15mg/kg 6h

PK:
A: 100% or 80%
D: 1L and pB of 10%
M: hepatic to mostly glucuronide and sulphate metabolites, but 10% to NAPQI (toxic). Rapidly conjugated by glutathione and excreted. Once depleted, accumulates causing liver failure.
E: renal

PD:
MOA: cox 3 reduced brain PGE levels. also modulates endogenous cannabinoids
C: rapid IV = hypotension
D: analgesia and antipyretic
Others: rash, thrombocytopenia and toxic in OD

Question 2

Tell me about aspirin?

Answer 2

NSAID that is analgesic, anti inflammatory and antiplatelet

Physical: salicylate
- 75 and 300 tablets.
X 3-60l for analgesia
- PKA of 3 so rapidly absorbed from stomach (acid)

PK:
A: Good OBA
D: 85% PB
M: metabolised by red cell and hepatic esterases to intermediate and then further to salicylate acid which is excreted
E: renal

PD:
MOA: irreversible cox 1, some cox 2 ans selectively inhibits thromboxane thromboxane inhibitor
B: 20% asthmatics
C: anti platelet and fluid retention in HF
F: reduced renal perfusion
G: GI bleed and transaminitis

Others: toxic in OD and Reyes in kids

Question 3

Tell me about diclofenac?

Answer 3

Phenylacetic acid derivative NSAId used for analgesia and anti-inflammatory properties

Physical:
- tablets, supps, topical gel and CCS in cupboard (25mg/ml)

PK:
A: we’ll absorbed by all routes but high first pass metabolism. Oral = 60%
D: Vd 0.2 and 99 PB
M: hepatic
E: renal

PD:
MOA: equal COX 1 and 2
B: 20% asthmatics
C: reversible platelet
D: analgesia
E: renin and aldosterone down 70%
F: reduced renal perfusion
G: less than aspirin

Others: effects neutrophil function