1. Drugs used in Treatment of
Gout
Dr. Pravin Prasad
M.B.B.S., MD Clinical Pharmacology
Lecturer, Lumbini Medical College & TH
22 March 2019 (8 Chaitra 2075), Friday
2. By the end of this class, MBBS 1st
Sem students will be able to:
Classify drugs used in the treatment of
gouty arthritis
Discuss the pharmacology of drugs used in
gouty arthritis
3. Gout
Is marked by transient
attacks of acute arthritis
initiated by crystallization
of monosodium urate
within and around joints
May also get deposited in
kidneys and subcutaneous
tissue (tophi)
Is always preceded by
hyperuricemia
4. Drugs useful in gout
Objective of treatment Drugs
Relieve inflammation
and pain
NSAIDs, colchicine,
glucocorticoids
Prevent inflammatory
responses
NSAIDs, colchicine
Inhibit urate formation Allopurinol, febuxostat
Augment urate
excretion
Probenecid
6. Colchicine
Alkaloid derived from C. autumnale
Specifically suppresses gouty
inflammation
Faster acting than NSAIDs
Control of attack 6-12 hrs
Complete resolution 3-5 days
Higher toxicity than NSAIDs
7. Colchicine: Mechanism of action
Acts by:
Inhibiting release of
chemotactic factors and
glycoproteins
Binds to fibrillar protein
and inhibits granulocyte
migration to joints
Also has amitotic action and
increases gut motility
• Subsequent
steps Inhibited
• Vicious cycle
interrupted
8. Colchicine: Pharmacokinetics
Rapidly absorbed orally
Partly metabolised by liver and excreted in bile
Undergoes hepatic circulation
Takes long to get eliminated
Metabolised by CYP3A4 isoenzymes
Drug interactions with enzyme inhibitors/inducers
Gets eliminated in urine and faeces
Dose reduction in renal impairment
10. Colchicine: Uses
To abort an attack of gout:
0.5-1.5 mg stat
To control an acute attack of gout:
Second line, fastest acting
0.5 mg 1-3 hourly, 4 doses in a day
Maximum dose: 6 mg over 3-4 days
As maintenance dose in gout:
0.5-1 mg/d (4-8 weeks)
11. Probenecid
Enhances excretion of uric acid by:
Blocking Urate transporter-1 (URAT-1)
A type of organic anion transport
protein (OATP)
Predominant reabsorption of uric acid
in kidney (PCTs)
Reabsorption of uric acid in PCT
inhibited
Excretion enhanced, blood urate level
falls
13. Probenecid: Indications
Chronic gout and hyperuricaemia
Second line drug
0.25 mg twice daily 0.5 mg twice daily
Colchicine/NSAIDs cover needed
Prolong action of penicillin
Gonorrhoea, Sub Acute Bacterial Endocarditis
Prevent cidofovir induced nephrotoxicity
CMV retinitis
14. Probenecid
Adverse effects:
Generally well tolerated
Dyspepsia
Caution in patients with peptic ulcer disease
Rashes, other hypersensitivity reaction
Avoid in patients with renal insufficiency, renal
calculi
Advice to drink plenty of fluids
15. Allopurinol
Substrate as well as inhibitor of xanthine oxidase
enzyme Purines
Hypoxanthine
Xanthine
Uric acid
Xanthine oxidase
Xanthine oxidase
Allopurinol
Alloxanthine
• Short acting
• Competitive inhibitor
• Long acting
• Non-competitive inhibitor
16. Allopurinol: Mechanism of action
Inhibits xanthine oxidase (XO)
Directly
By getting converted to alloxanthine
Decreased concentration of uric acid in plasma
Hypoxanthine and xanthine concentration
increased
All three metabolites excreted in urine
Increase hypoxanthine and xanthine leads to
feedback inhibition of de novo purine synthesis as
well
17. Allupurinol
Pharmacokinetics:
Metabolised largely to alloxanthine
Metabolism inhibited on chronic
administration
Interactions:
Inhibits degradation of 6-mercaptopurine,
azathioprine, warfarin, theophylline
Complex interaction with probenecid
18. Allopurinol: Indications
Chronic gout
First line drug
Given for long duration
100 mg/d 300 mg/d; maximum 600 mg/d
Patients advised to drink plenty of water
Secondary hyperuricaemia
Potentiate 6-MP, azathioprine
20. Febuxostat
Non-purine XO inhibitor
Adverse effect:
Liver damage
Hypersensitivity reaction
Diarrhoea, nausea, headache
Used as an alternative to allopurinol
Not to be combined with allopurinol
Dose: 40 mg/d 80 mg/d; maximum 120 mg/d
21. Pegloticase
Recombinant uricase
Oxidises uric acid to allantoin
Highly soluble
Coupled to methoxy polyethylene glycol
Refractory symptomatic gout
Given intravenously, every 2 weeks
ADRs: infusion reactions, development of
antibodies
Pegylated
For uric acid
Metabolising enzyme
22. NSAIDs in Gout
Naproxen, indomethacin, diclofenac, etoricoxib
Better tolerated than colchicine
Uses:
To terminate the attack of acute gout
Frequent high doses
Takes 12-24 hours, complete resolution in 5-10
days
As a cover till effects of other anti-gout drug
effects develops
23. NSAIDs in gout
Drug Dose
Naproxen 750 mg stat 250 mg, three
times a day till attack
subsides
Indomethacin 50 mg, three time a day till
attack subsides 25 mg
three time a day for 5-7 days
Diclofenac 50-75 mg, three times a day
Etoricoxib 60-120 mg, once daily
24. Corticosteroids in gout
Suppress symptoms of acute gout
Can be given by:
Intraarterial injection
Triamcinolone 10-30 mg
Avoid crystalline preparation
Indicated when few joints are involved, those
not tolerating NSAIDs/colchicine
25. Corticosteroids in gout
Suppress symptoms of acute gout
Can be given by:
Systemic administration (oral)
Indicated for patients with renal failure/peptic
ulcer, non-responders, not tolerating
Prednisolone 40-60 mg tapered over 1-2
weeks
26. Conclusion
NSAIDs are the drug of choice for treatment of
acute gout
Indomethacin, naproxen
Allopurinol is the drug of choice for treatment of
chronic gout
Probenecid cannot be used in patients with
renal impairment, and is associated with risk of
renal stones
27. Let’s have a break…
Any queries?
Next class:
Skeletal muscle relaxants
Thank you