Phenacetin

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Name: Phenacetin

Class: Para-aminophenol

Mechanism: Converted to acetaminophen. Weak inhib. of peripheral prostaglandin synth. More effective CNS cyclooxygenase inhib. ® antipyretic and analgesic properties.

Absorption: Oral ® rapid & complete. Not a weak acid.

Dist.: Dist. throughout body fluids. Protein binding (20-50%) not significant.

Metabolism.: No zero-order kinetics. Phase II conjug. w/glucuronic acid & sulfate. Phase I oxid. ® N-acetyl-benzoquinoneimine. Reacts w/sulfhydryl groups, but normally inactivated by glutathione (except in overdose).

Excretion, : Majority excreted as conjug. Metabolismolites in urine. Not related to urine pH.

Toxicity/S.E.s: Nephropathy assoc. w/chronic use. Overdose ® depletion of hepatic glutathione ® rxn. w/sulfhydryl groups of hepatic proteins ® hepatic necrosis. Also renal tubular necrosis. Treatment w/N-acetylcysteine w/in 10 hr. of overdose can be life-saving.

Utility: Analgesic and antipyretic efficacies comparable to aspirin.

Special Features: No longer prescribable in US due to renal toxicity. Weak peripheral inhib. ® weak anti-inflammatory activity. No urocosuric or anti-platelet effects.

 

Acetaminophen (Tylenol)

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Name: Acetaminophen (Tylenol)

Class: Para-aminophenol (OTC)

Mechanism: Weak inhib. of peripheral prostaglandin synth. More effective CNS cyclooxygenase inhib. ® antipyretic and analgesic properties.

Absorption: Oral ® rapid & complete w/peak in 30-60 min. Not a weak acid.

Dist.: Dist. throughout body fluids. Protein binding (20-50%) not significant.

Metabolism.: No zero-order kinetics. Phase II conjug. w/glucuronic acid & sulfate. Phase I oxid. ® N-acetyl-benzoquinoneimine. Reacts w/sulfhydryl groups, but normally inactivated by glutathione (except in overdose).

Excretion, : Majority excreted as conjug. Metabolismolites in urine. Not related to urine pH. 2 hr.

Toxicity/S.E.s: Overdose ® depletion of hepatic glutathione ® rxn. w/sulfhydryl groups of hepatic proteins ® hepatic necrosis. Also renal tubular necrosis. Treatment w/N-acetylcysteine w/in 10 hr. of overdose can be life-saving.

Utility: Analgesic and antipyretic efficacies comparable to aspirin.

Special Features: Para-aminophenol prototype. Often used w/other analgesics (e.g., Tylenol + Codeine). Weak peripheral inhib. ® weak anti-inflammatory activity. No urocosuric or anti-platelet effects.

 

Colchicine

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Name: Colchicine

Class: Anti-Gout Agent

Mechanism: Binds to tubulin ® inhib. of leukocyte migration & phagocytosis ®
¯ inflamm. response.

Absorption: Rapidly absorbed orally.

Dist.:

Metabolism.:

Excretion, : Urine & feces.

Toxicity/S.E.s: GI intolerance (n/v/d).

Utility: Treat acute gout attacks. Use to prevent acute attacks while initiating allopurinol or probenecid therapy.

Special Features: Not analgesic. No effect on uric acid production or excretion.

 

Allopurinol (Zyloprim)

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Name: Allopurinol (Zyloprim)

Class: Anti-Gout Agent

Mechanism: Inhibits xanthine oxidase ® ¯ production of uric acid.

Absorption: Well absorbed orally.

Dist.:

Metabolism.: Metabolism. by xanthine oxidase to a longer acting active Metabolismolite.

Excretion, :

Toxicity/S.E.s: GI intolerance, skin rash.

Drug Interactions: Inhib. Metabolism. of oral anticoagulants. Xanthine oxidase inactivates 6-mercaptopurine & azathioprine (cancer chemotherapeutic drugs). \ doses must be lowered when patient takes allopurinol.

Utility: Treat chronic tophaceous gout, gout patients w/high excretion of uric acid, patients who cannot use probenecid or sulfinpyrazone, recurrent renal uric acid stones, renal impairment, grossly elevated serum acid concentrations (>13 mg/dL). Use also w/cancer chemotherapy to prevent urate nephropathy.

Special Features:

 

Sulfinpyrazone (Anturane)

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Name: Sulfinpyrazone (Anturane)

Class: Anti-Gout Agent (Uricosuric Agent)

Mechanism: Blocks proximal tubular reabsorption of uric acid.

Absorption:

Dist.:

Metabolism.:

Excretion, : Rapidly excreted by the kidneys.

Toxicity/S.E.s: GI irritation (not severe). Skin rash. Rare aplastic anemia.

Utility: Treat gout via increased urinary excretion of uric acid.

Special Features: At low doses, sulfinpyrazone blocks proximal tubule secretion
of uric acid.

 

Probenecid (Benemid)

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Name: Probenecid (Benemid)

Class: Anti-Gout Agent (Uricosuric Agent)

Mechanism: Blocks proximal tubular reabsorption of uric acid.

Absorption:

Dist.:

Metabolism.:

Excretion, : Reabsorbed by renal tubules & Metabolismolized slowly.

Toxicity/S.E.s: GI irritation (not severe). Skin rash. Rare aplastic anemia.

Utility: Treat gout via increased urinary excretion of uric acid. Blocks tubular secretion of penicillin; may be used to increase penicillin levels.

Special Features: At low doses, probenecid blocks proximal tubule secretion of uric acid.

 

Levamisole (Ergamisol)

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Name: Levamisole (Ergamisol)

Class: Slow-Acting Antirheumatic Agent (Veterinary Anti-Helminthic Agent)

Mechanism: Enhances cell-mediated immune responses (­ chemotaxis & phagocytosis of PMNs and Mfs, ­ T cell fxn). How these effects ameliorate RA is unknown.

Absorption:

Dist.:

Metabolism.:

Excretion, :

Toxicity/S.E.s: Rash (most common), leukopenia, agranulocytosis, thrombocytopenia, influenza-like illnesses, mouth ulcers, n/v.

Utility: Treat rheumatoid arthritis (off-label use).

Special Features:

 

Sulfasalazine (Azulfidine)

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Name: Sulfasalazine (Azulfidine)

Class: Sulfonamide (Slow-Acting Antirheumatic Agent)

Mechanism: Comp. inhib. of PABA incorp. into dihydropteric acid ® inhib. of folic acid.

Absorption: Poorly absorbed in GI tract.

Distribution: GI tract

Metabolism.: Hydrolyzed to active form by intest. bacteria.

Excretion, t½: feces

Toxicity/S.E.s: Interferes w/normal flora ® ¯ vit. K synth.

Utility: Active in bowel lumen. Used prior to surgery to reduce microbe population. Treat inflammatory bowel disease, rheumatoid arthritis.

Special Features: Broken down in intestines to liberate 5-aminosalicylate (anti-inflammatory).