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Dr.U.P.Rathnakar. MD.DIH.PGDHM
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Dr.Rathnakar U.P.MD.DIH.PGDHM
Phamacotherapy of Gout
Gout Metabolic disorder preceded by hyperuricemiaPrecipitation of sodim urate crystals in the
tissues ⇛inflammatory response. . .
Excess uric acid
Sodium
Sodium
urate
Accumulates in Soft tissue
Secondary Hyperuricemia
Leukemias, lymphomas, Polycythemias when treated with
radiation/chemotherapy
Drug induced: thiazides, frusemide, ethacrynic acid, ethambutol, Pyrazinamide.
Ethanol, clofibrate
Diabetic ketoacidosis, lead poisoning, psoriasis
Hperuricemia MSU crystals depositedIn joints
Phagocytosed by synoviocytes
•Release infl.mediators•[PG,Lysozomal enzymes.IL-1]
•PMN migrate to joint •Phagocytose MSU•RELEASES A GLYCOPROTEIN
Amplifies inflammationLowers pH
Further precipitation of urates
•Phagocytosed by• Macrophages
Sequence of
eventsAt
mol.level
Clinical presentation of gout
Chronic TophaceousGout
AcuteGout
DiagnosisDefinitive diagnosis IN synovial fluid or
Tophaceous material Demonstration of MSU
crystals
Polarized microscopy,
Synovial Fluid Findings
Needle shaped crystals of monosodium urate monohydrate
Engulfed by neutrophils
Drugs used in GoutClassification
Drugs used for acute gout:NSAIDSColchicineCorticosteroids
Drugs used for chronic gout:Uricosurics: Probenecid, SulfinpyrazoneUric acid Synthesis inhibitor: Allopurinol
NSAIDsIndomethacin, naproxen, piroxicam, diclofenac potassium
Except aspirin, salicylates & tolmetin
Inhibit urate crystal phagocytosis & migration of leukocytes → inflamed joint
Not recommended for long term useIndomethacin:50mg QID→ 25mg QID
Drugs used in GoutClassification
Drugs used for acute gout:NSAIDSColchicine
Drugs used for chronic gout:
ColchicineObtained from Colchicum autumnale
No analgesic/anti-inflammatory action
No effect on blood uric acid levels
Hperuricemia MSU crystals depositedIn joints
Phagocytosed by synoviocytes
•Release infl.mediators•[PG,Lysozomal enzymes.IL-1]
•PMN migrate to joint •Phagocytose MSU•RELEASES A GLYCOPROTEIN
Amplifies inflammationLowers pH
Further precipitation of urates
•Phagocytosed by• Macrophages
Sequence of
events
Colchicine---MOA1. Inhibits release of glycoprotein2. Binds to‘tubulin’ →
depolymerisation/disappearance of microtubules prevents migration of granulocytes
Other actions1. Antimitotic-Metaphase arrest2. Increases gut motility
Spindle poisons:MebendazoleColchicineGriseofulvinVinca AlkaloidsPaclitaxel
Mitotic spindle is essential for equal partitioning of DNAduring cell division
Pharmacokinetics
Rapid oral absorptionPartly metabolized in liverExcreted in bile-enterohepatic circulation
Ultimately excreted in urine & faeces
Gout-ColchicineAcute:1mg→0.25 mg 3 h till controlled or diarrhoea starts
Dramatic response-Diagnostic
Prophylactic: 0.5 mg/day
Other usesFamilial mediterranean feverPrimary biliary cirrhosisSarcoid arthritis
ADEDiarrhoea(bloody), pain abdomen &
vomitingRespiratory depression, throat pain,
haematuria & oliguriaAgranulocytosis, peripheral neuritis &
myopathy
Nausea
G.I.Disturbances
Diarrhoea
Agranulocytosis
Alopecia
ADE OF COLCHICINE
Drugs used in GoutClassification
Drugs used for acute gout:NSAIDSColchicineCorticosteroids
Drugs used for chronic gout:
Corticosteroids Intraarticular injection of Soluble
steroidsCrystalline preparations should not be
usedIndicated in
Refractory casesIntolerance to NSAIDs or Colchicine
Systemic steroids- Prednisolone- reserved for severe cases
Drugs used in GoutClassification
Drugs used for acute gout:NSAIDSColchicineCorticosteroids
Drugs used for chronic gout:Uricosurics: Probenecid, SulfinpyrazoneUric acid Synthesis inhibitor: Allopurinol
URATE LOWERING TREATMENT
Who to treat? 1. Tophi 2. Gouty athropathy 3. Radiographic changes of gout 4. Multiple joint involvement 5. Nephrolithiasis
ProbenecidCompetitive inhibition of active transport of organic acids at all sites especially at renal tubules
Penicillin ⇨predominantly secreted; minimal absorptionNet effect⇨ probenecid inhibits secretion ⇨⇪blood levels
Uric acid⇨ largely reabsorbedNet effect⇛ Probenecid promotes excretion ⇨⇩blood levels
Probenecid Probenecid [Decreases plasma concn of UA] [Increases concn of penicillins]
URIC ACID PENICILLIN [Absorption] [Excretion]
Lumen
Renal tubule
TRANSPORTER
Pharmacokinetics
Complete oral absorption90% plasma protein bound
Conjugated in liver & excreted in urine
Plasma t1/2 = 8-10 hrs
Drug interactionsProbenecid Inhibits: Excretion of
Penicillins, Cephalosporins, Sulfonamides, Methotrexate,Indomethacin
Inhibits Biliary excretion of Rifampin
Inhibits Secretion of nitrofurantoin ⇛fails to attain anti
bacterial conc in urineUricosuric action of Probenecid is blocked by
salicylates
Uses: Probenecid 1. Chronic gout:
With plenty of water + alkalinisation of urine:To prevent crystallization of excess urate in urinary tract
Life long treatment is often requiredNot to be started during acute attack; dealt with NSAIDs
No use if kidney is damaged2. Also in Secondary hyperuricemia3. Prolong action of Penicillin/Ampicillin
Sulfinpyrazone Uricosuric drugInhibits tubular reabsorption of uric acid
Uricosuric action: additive with Probenecid Antagonised by salicylates
Inhibits platelet aggregation
BenzbromaroneNewer, more potent uricosuric drug
Used in patients allergic or refractory to probenecid or sulfinpyrazone
Patients with renal insufficiencyReversible inhibitor of tubular reabsorption of uric acidADE: Fulminant liver failure
Drugs used in GoutClassification
Drugs used for acute gout:NSAIDSColchicineCorticosteroids
Drugs used for chronic gout:Uricosurics: Probenecid, SulfinpyrazoneUric acid Synthesis inhibitor: Allopurinol
Hypoxanthine
Xanthine
Uric acid
Xanthine oxidase
Xanthine oxidase
Alloxanthine
Allopurinol
Allopurinol
Xanthine oxidase
Pharmacokinetics 80% orally absorbedNot bound to plasma proteins
Metabolized largely to Alloxanthine
Chronic use: inhibits its own metabolism
Drug interactions of Allopurinol
Inhibits degradation of 6-mercaptopurine & azathioprine
Probenecid shortens t1/2 of alloxanthineAllopurinol prolongs t1/2 of probenecid
Potentiates warfarin & theophyllineAmpicillin + Allopurinol ⇨⇪ rashes
Iron therapy is not recommended
AllopurinolAdverse effects:Hypersensitivity reactions: rashes, fever, malaise & muscle pain; STEVENS JOHNSON SYNDROME
Gastric irritation, headache, nausea & dizziness
Rarely liver damage
AllopurinolContraindications: • Hypersensitive • Pregnant & lactating
mothers • Elderly & children • Liver & kidney disease
AllopurinolOther uses:
Secondary hyperuricemiaTo potentiate 6-mercaptopurine or Azathioprine
Kala-azar: inhibits Leishmania by altering purine metabolism
RasburicaseRecombinant urate-oxidase
Produced by a genetically modified Saccharomyces cerevisiae strain
Lowers urate levels more effectively than allopurinol
RasburicaseIndicated for
With anti cancer therapy in children
Adverse efffects:Hemolysis in -(G6PD)-deficient patients, methemoglobinemia, acute renal failure, and anaphylaxis
Route of administration
SJSallopurinol, diclofenac, fluconazole, valdecoxib, penicillins, barbiturates, sulfonamides, phenytoin, azithromycin, lamotrigine, nevirapine, ibuprofen[8], ethosuximide, carbamazepine
Choi, H. K. et. al. Ann Intern Med 2005;143:499-516
GoutWhat is gout-Purine metabolismInflammation of jointsMOA of inflammationDrugs—Acute and chronic