Gout is a type of inflammatory arthritis that causes permanent disability if left untreated. This presentation focuses on the important salient points we need to remember in Gout in all aspects - diagnosis, managment (both non-pharmacological and pharmacological approaches). This presentation is useful to both MBBS and Postgraduate students of Pharmacology.

1. Dr.S.Arun M.B.B.S;
First year Post Graduate
Department of Pharmacology

2. PH 1.16 - ANTI-GOUT DRUGS
SPECIFIC LEARNING OBJECTIVES
• INTRODUCTION
• GOUT - RISK FACTORS
• GOUT - PATHOPHYSIOLOGY
• DIAGNOSIS OF GOUT
• DRUGS FOR ACUTE GOUT
• DRUGS FOR CHRONIC GOUT
• APPROACH TO ACUTE AND CHRONIC GOUT
• SUMMARY
• CASE SCENARIO
• ASSESSMENT

3. WHY DO WE NEED TO LEARN ABOUT GOUT?

6. WHAT IS GOUT?

7. • Gout is a metabolic disorder - due to increased body levels of uric acid.
• Cardinal features of Gout:
1. Arthritis (body’s reaction to the deposition of Monosodium urate
crystals in the joint)
2. Painless deposition of urate crystals in the soft tissues such as
cartilage, bursae and tendons in pinna, eyelids, nose, around joints.
3. Development of tophi - due to recurrent gouty arthritis.
4. Renal calculi and nephropathy.

9. RISK FACTORS FOR GOUT

11. CAUSES OF SECONDARY HYPERURICAEMIA
• Renal impairment
• Massive lysis of cells during cancer chemotherapy
• Drugs:
1. CNS stimulants - alcohol
2. Diuretics - Thiazides, loop diuretics, amiloride
3. Anti-TB drugs - Ethambutol, pyrazinamide
4. NSAIDS - salicylates
5. Chemotherapy drugs - Cyclosporine
6. Anti-parkinson’s drug - Levodopa
7. Vitamins - B3 (Niacin)

12. URIC ACID
METABOLISM

13. PATHOPHYSIOLOGY OF GOUT

14. Uric acid accumulates in joints and crystallise
↓
Induces inflammatory response in joints
↓
Granulocytes migrate to the joint by chemotaxis
↓
Granulocytes engulf the MSU cyystals by phagocytosis and release of lysosomal
enzymes and glycoprotein
↓
Release of lactic acid and more acidic pH
↓
More precipitation of urate crystals
↓
Acute Gout attack

16. CLINICAL SIGNS AND SYMPTOMS
• Initial episode of gout -
acute painful arthritis
that begins at night with
dramatic joint pain and
swelling (mimics
cellulitis)

17. JOINTS INVOLVED

19. HOW TO DIAGNOSE GOUT?
• Clinical findings - arthritis (single, acute, hot,
swollen, painful)
• Presence of tophi
• Synovial fluid aspiration analysis - presence of
monosodium urate crystals.
• Radiological findings:
1. Joint erosions
2. Renal stones

22. TREATMENT OF GOUT
NON-
PHARMACOLOGICAL
PHARMACOLOGICAL

23. NON-PHARMACOLOGICAL TREATMENT
• Diet modification:
1. Consume regularily - cereals, pulses, fruits, vegetables, low fat
milk, plenty of water.
2. Can consume - Tea, coffee, spices, beans, legumes, egg (with
caution), less salt in diet.
3. Avoid Carbonated beverages which contain added phosphoric
acid - can precipate renal calculi (calcium oxalate stones)
4. Avoid consumption of fatty meats (red meat), sea food.
• Correct obesity
• Avoid alcohol consumption

24. PHARMACOLOGICAL TREATMENT

25. ANTI-GOUT DRUGS

26. DRUGS FOR ACUTE GOUT

27. DRUGS USED
IN ACUTE
GOUT
MECHANISM
OF ACTION
ADVERSE DRUG
EFFECTS
PRECAUTIONS INTERACTIONS DOSAGE AND
DURATION OF
TREATMENT
NSAIDS -
Indomethacin,
Naproxen,
Ibuprofen
Inhibits
Cyclooxygenas
e and prevents
formation of
prostaglandins
& interleukins
Gastritis,
Headache,
neuropsychiatric
ADRs, fluid
retention, Acute
kidney injury.
Avoid NSAIDs
in patients
with
cardiovascular
disease and
peptic ulcer
disease.
ACE inhibitors,
thiazide
diuretics should
not be given.
Ketorolac should
be avoided.
Indomethacin
25-50 mg t.i.d x
7 days (or)
Naproxen 500
mg b.d x 5
days.
COLCHICINE Causes
microtubule
damage by
binding to
tubulin.
Granulocyte
migration is
affected.
GI upset, severe
diarrhoea,
agranulocytosis,
myopathy.
Overdose may
cause death due
to muscular
paralysis and
respiratory
failure.
Colchicine
therapy should
not be
repeated
within 4 -7
days of
initializing
treatment for
acute gout
attacks.
P-glycoprotein &
CYP 3A4
inhibitors can
cause fatal
toxicity of
colchicine (as it
is metabolised
by CYP3A4 and
effluxed
normally by P-
gp)
0.5 mg orally
every 1-3hrs -
total 4 doses in
a day; total
dose 6mg in 4
days. Stop for 7
days. Then
Start
maintenance
therapy - 0.5-

28. ADDITIONAL POINTS ON COLCHICINE
• Colchicine has
1. No analgesic action
2. No anti-inflammatory action
3. No effect on blood uric acid levels
• Possible mechanisms of action of colchicine:
1. Prevents granulocyte migration into the inflammed joint.
2. Inhibits the release of glycoprotein from granulocytes.
3. Binds to tubulin and causes disappearance of microtubules in
granulocytes. (“Drunken walk” of neutrophils treated by colchicine)

29. ROLE OF STEROIDS IN ACUTE GOUT
• Consider intra-articular injection of
triamcinolone 10-30mg if large joint
involvement
• Systemic steroids - are indicated for
patients with renal failure / h/o
peptic ulcer disease.
• Prednisone 0.5 mg/kg per day
(effective dose: 40-60 mg/day)
orally × 1 day followed by tapering
doses.
• Steroids can cause hyperglycemia—
avoid use in patients with diabetes
• Monitor for adverse effects (e.g.,
insomnia, GI upset, agitation)

30. DRUGS FOR CHRONIC GOUT
(URIC ACID LOWERING THERAPY)

31. URICOSURICS
DRUGS USED
IN CHRONIC
GOUT
MECHANISM
OF ACTION
ADVERSE
DRUG
EFFECTS
INDICATIONS PRECAUTIONS INTERACTIONS DOSAGE
AND
DURATION
OF
TREATMENT
PROBENECI
D
Inhibits
URAT-1
transporter -
prevents
reabsorption
of uric acid
Dyspepsi
a, rash
• Chronic
gout
• In
Gonorrhoe
a and
SABE (to
prolong
penicillin
action)
• In CMV
retinitis -
to prevent
the
toxicity of
Cautiously
used in peptic
ulcer disease
as it causes
indigestion
(dyspepsia),
avoided in
renal failure
and patients
with serum
creatinine >
2mg/dL
• Probenecid
inhibits
urinary
excretion of
penicillins,
cephalosporins
.
• Inhibits biliary
excretion of
rifampicin.
• Inhibits
urinary
excretion of
nitrofurantoin.
0.25 g BD
initially
followed by
0.5 g BD for
a long time.

32. OTHER URICOSURICS
SULFINPYRAZONE:
• Also inhibits tubular reabsorption of uric acid.
• Not used nowadays due to adverse effects like severe gastric
irritation.
BENZBROMARONE:
• It is a potent uricosuric drug.
• Can be also given in patients with GFR reduced to 25-50% of
normal.

33. OTHER URICOSURICS - contd..
AZAPROPAZONE:
• It is an uricosuric drug with weak analgesic, anti-pyretic and anti-
inflammatory actions. Causes ADRs like GI upset and headache.
• It is relatively toxic.
• Also used in Rheumatoid arthritis and Osteoarthritis
LESINURAD:
• New uricosuric drug recently approved by US-FDA.
• Also inhibits tubular reabsorption of uric acid.
• Can be used alone or in combination with a xanthine oxidase
inhibitor.

34. URIC ACID SYNTHESIS INHIBITORS
DRUGS USED
IN CHRONIC
GOUT
MECHANISM
OF ACTION
ADVERSE
DRUG
EFFECTS
PRECAUTIONS INTERACTIONS DOSAGE AND
DURATION OF
TREATMENT
ALLOPURINOL Allopurinol is
converted to
alloxanthine
which non-
competitively
inhibits
Xanthine
oxidase
enzyme. So
more of
xanthines and
hypoxanthines
are excreted via
kidney.
Fever,
malaise,
muscle pain,
gastric
irritation,
nausea, SJS
syndrome
• Contraindicated
in pregnancy
and lactation.
• Cautiously used
in children,
elderly and in
patients with
kidney / liver
disease.
• Inhibits
degradation of
azathioprine
and 6-
mercapto
purine.
• Inhibits
metabolism of
warfarin and
theophylline.
• Allopurinol
when given
with ampicillin
- increased
skin rashes
• These drugs
should not
be given in
1-2 months
of acute
gout
attacks.
• Dosage -
100 mg OD
initially,
gradually
increase to
300mg /
day for life
long.

35. URIC ACID SYNTHESIS INHIBITORS - contd..
DRUGS USED
IN CHRONIC
GOUT
MECHANISM
OF ACTION
ADVERSE
DRUG
EFFECTS
PRECAUTIONS INTERACTIONS DOSAGE AND
DURATION OF
TREATMENT
FEBUXOSTAT Xanthine
oxidase
inhibitor
silimar to
allopurinol
Diarrhoea,
nausea,
headache
• Not indicated in
malignancy
associated
hyperuicemia.
• Not to be
combined with
allopurinol for
treatment.
Interacts with
mercaptopurine,
azathioprine &
theophylline and
modifies their
metabolism.
• These drugs
should not
be given in 1-
2 months of
acute gout
attacks.
• Dosage -
40mg OD
initially,
increase
gradually to
80 mg OD.

36. OTHER DRUGS IN CHRONIC GOUT

37. URICASE MIMETIC AGENTS
PEGLOTICASE:
• It is a Recombinant uricase (enzyme which breaks uric acid to
allantoin)
• Humans lack this enzyme normally
• This drug is given by intravenous infusion every 2 weeks.
• Single dose infusion reduces uric acid levels in blood upto 21 days.
• Useful in refractory gout not responding to any Anti-gout drugs.
• The drug is immunogenic and can generate antibodies against it. So
may result in hypersensitivity reactions, anaphylaxis.

38. URICASE MIMETIC AGENTS - contd..
RASBURICASE:
• Mechanism of action similar to pegloticase.
• This drug is given by intravenous infusion once a day for 5 days -
on every dosing of chemotherapy.
• Useful in reduce elevated uric acid levels in tumour lysis syndrome.
• ADRs - vomitting, fever, headache, mucositis, acute renal failure,
anaphylaxis, hemolysis in G-6-PD deficiency patients.

39. APPROACH TO PHARMACOLOGICAL TREATMENT
• To treat acute gouty arthritis:
1. NSAIDs
2. Colchicine
3. Corticosteroids
• To prevent acute attacks
1. Colchicine
2. NSAIDs

40. APPROACH TO TREATMENT OF CHRONIC GOUT
• Indications for Urate (Uric acid) lowering therapy:
1. Acute attacks with serum uric acid > 9 mg/dL
2. Patient had at least 2 definite attacks of acute gouty arthritis or has
developed tophi.
3. The patient agrees to take the medication lifelong.
• Initial treatment for chronic gout should be with uric acid
synthesis inhibitors (Xanthine oxidase inhibitors).
• If this fails, uricosurics should be added.

41. ACUTE EXACERBATIONS OF CHRONIC GOUT
• When patients with chronic gout taking urate lowering therapy,
suffer from acute attacks of arthritis in between, two things should
be done.
1. Stopping the Urate lowering drugs for 2 months
2. Start the patient on NSAIDs for 4 weeks.
3. Start the patient on Colchicine and continue for 1 year
4. After 2 months of attack, restart on Urate lowering drugs.

42. TO SUMMARIZE
• Gout is an inflammatory arthritis affecting males > 50 years with features of pain
& swelling of the joints (great toe m/c), tophi formation and permanent disability
of the joint if left untreated.
• Proper dietary modification, plenty of fuild intake and reduction in red meat
consumption can prevent gout development.
• Xanthine oxidase enzyme is the rate limiting enzyme in uric acid metabolism.
• NSAIDs (Indomethacin) are the first line drugs in acute gout, given for 4-6 weeks.
• Steroids can be given as intra-articular injection if large joints are involved.
• Colchicine should be given for atleast 2 months to 1 year after an episode of acute
gout. But may cause severe diarrhoea (in that case reduce the dosing).
• Uricosurics (Probenecid) and Uric acid synthesis inhibitors (Allopurinol &
Febuxostat) reduce uric acid levels in chronic gout and are not useful in acute gout.
• Pegloticase is given in refractory gout, Rasburicase is given in tumor lysis
syndrome.

43. CASE SCENARIOS
1. A 53 year old man recently diagnosed with gouty arthritis started a
treatment with a drug that inhibits leucocyte migration and
phagocytosis (by binding to tubulin). Which of the following drugs
most likely did the patient take?
Answer - Colchicine

44. 2. A 48-year-old man was admitted to the emergency department with
the chief complaint of an excruciating pain in his left ankle. The pain
had started the previous night and increased over several hours. The
patient reported that he sprained his ankle 1 week ago. On physical
examination, the ankle appeared warm and tender, and the entire area
was red and swollen. A synovial fluid analysis showed crystals engulfed
by phagocytes. A diagnosis was made, and a pharmacotherapy was
prescribed. Which drug would be most appropriate to treat the patient’s
pain?
Answer - NSAIDs (Indomethacin)

45. ASSESSMENT
1. Which of the following anti-gout drugs act at the site marked by
arrow in the image?
(a) Indomethacin
(b) Colchicine
(c) Allopurinol
(d) Rasburicase
(b) Colchicine

46. 2. The most common effect of colchicine which is dose limiting is:
(a) Diarrhea
(b) Dyspepsia
(c) Retinal damage
(d) Loss of taste sensation
(a) Diarrhea

47. 3. Allopurinol works on the basis of:
(a) Decreased excretion of uric acid
(b) Decreased metabolism of uric acid
(c) Increased excretion of uric acid
(d) Decreased synthesis of uric acid
(d) Decreased synthesis of uric acid

48. 4. Probenecid interacts with:
(a) Streptomycin
(b) Penicillin
(c) Vancomycin
(d) Erythromycin
(b) Penicillin

49. 5. Which of the following increases uric acid excretion?
(a) Allopurinol
(b) Aspirin
(c) Colchicine
(d) Probenecid
(d) Probenecid