Analgesics Flashcards
Define analgesic?
Drugs that relief pain by central actions without loss of consciousness
Analgesics can be classified into?
- Opioid (narcotic) analgesics: morphine.
- Nonsteroidal anti-inflammatory drugs (NSAIDS)/ non-opioid: Aspirin.
Mechanism of action of NSAIDs?
1.Inhibition of cyclooxygenase enzyme leading to inhibition of synthesis of
PGs and TXA2 leading
to analgesic, antipyretic, anti- inflammatory effect& anti-platelet effect.
2.All NSAIDs are reversible cox inhibitor except aspirin which cause irreversible inhibition of Cox enzyme by acetylation.
3.Duration of action of aspirin depends on the rate of synthesis of new COX, which occurs within 4-6 h.
4.There are 3 isoforms of cox enzyme :
> Cyclooxygenase 1(Cox -1)
> Cyclooxygenase 2(Cox -2)
> Cyclooxygenase 3(Cox -3)
Compare between the 3 isoforms of cox enzyme?
~ Cyclooxygenase 1(Cox-1):
Constitutive enzyme present under
normal conditions.
• catalyze the formation of
physiological PGs which have:
1-Cytoprotective effect on gastric
mucosa ( decrease HCl, ↑mucous, HCO3)
2-Physiological PGs have vasodilator
effect which increase renal blood flow.
~ Cyclooxygenase 2(Cox -2):
Inducible enzyme, not normally present but it is induced in damaged tissue by
inflammatory cytokines as (Il-1,TNF-α).
Catalyze formation of pathological PGs➜ pain fever, Inflammation.
~ Cyclooxygenase 3(Cox -3):
Found only in CNS and stimulate
synthesis of PGs causing pain, fever.
> NSAIDs can be classified according to their selectivity into?
A.Non selective cox inhibitors : inhibition of Cox - 1 , Cox - 2 enzyme .
> Cox - 1 inhibition cause inhibition of physiological PGs synthesis which cause gastric ulceration and renal impairment.
Cox - 2 inhibition cause inhibition in synthesis of pathological PGs which reduce pain , fever , inflammation
B.Selective cox - II inhibitors:
- Highly selective ( COXIBS ):
• They act as analgesic , antipyretic , anti - inflammatory as non - selective cox - inhibitors .
•They main advantages over non selective cox - inhibitors : They don’t cause gastric ulceration , bleeding
-Slight selective :
•It is associated with fewer GI symptoms
•Long duration that allow once daily dosing
3.Selective cox - III inhibitors
(pharaminophenols):
They are analgesic , antipyretics but they are not anti - inflammatory because they inhibit PGs synthesis centrally and not peripherally .
Mention drugs that are a non selective cox inhibitors and are acetic acid derivatives?
K.I.D S.E.T (2> in / 4>ac)
Ketorolac (ac)
Indomethacin (in)
Diclofenac (ac)
Suldinac (ac)
Etodolac (ac)
Tolmetin (in)
Mention drugs that are a non selective cox inhibitors and are Salicylic acid derivatives ( salicylates )?
SA / SS/ ASA / MSA
Salicylic acid ( only locally ) SA
Sodium salicylate SS
Acetyl salicylic acid ( aspirin ) ASA
Methyl salicylic acid ( locally ) MSA
Mention drugs that are a non selective cox inhibitors and are Propionic acid derivatives?
N.O K.F.I (profen)
Naproxen
Oxaprozin
Ketoprofen
Fenoprofen
Ibuprofen
Mention drugs that are a non selective cox inhibitors and are Fenamic acid derivatives?
Me / Meclo / Flu
Mefenamic acid
Meclofenamic
Flufenamic
Mention drugs that are a non selective cox inhibitors and are
Oxicams derivatives?
Piroxicam
Drugs act as non - selective cox - inhibitors and their main advantages over non selective cox - inhibitors that they don’t cause gastric ulceration , bleeding?
C.L.E.V.R (coxib)
Celecoxib
Lumiracoxib
Etoricoxib
Valdecoxib
Rofecoxib
(Highly selective drugs)
Selective cox - II inhibitors drugs associated with fewer GI symptoms
Long duration that allow once daily dosing?
N.E.M
Nabumetone
Etodolac (acetic acid)
Meloxicam
Slight selective cox-II inhibitors
Selective cox - III inhibitors
(pharaminophenols) that are analgesic , antipyretics but they are not anti - inflammatory ?
+ mention why it’s not anti - inflammatory?
paracetamol , because it inhibit PGs synthesis centrally and not peripherally .
