Antituberculosis & Joint Pain

	Arthalgia Type 1	Arthalgia Type 2 (Gouty Arthritis)
Possible Causative Agent	pyrazinamide>>ethambutol> isoniazid	pyrazinamide>>ethambutol
Clinical Presentation	Pain and tenderness of joints: fingers, shoulders, knees, etc. (usually mild)	Symptoms : pain, tenderness and swelling of joints (fingers, shoulders, knees, etc) Symptoms are usually severe  Signs: elevated serum uric acid concentrations
Management	TB medications do not require discontinuation Symptomatic relief:  NSAIDS	TB medications usually do not require discontinuation If acute swelling is present examined for urate crystals to confirm the diagnosis of acute gouty arthritis. Symptomatic relief:  NSAIDS or colchicine (as alternative to NSAIDS) If recurrent episodes occur, may consider using prophylactic colchicine

Proposed Mechanism

• A metabolite of pyrizinamide, pyrinazoic acid, inhibits the renal tubular secretion of uric acid and ethambutol reduces its renal clearance.

• The resulting hyperuricaemia can give rise to arthralgias and very rarely an arthritis.

Reference; 

1. http://rheumatology.oxfordjournals.org/content/45/9/1173.full
2.  http://www.uphs.upenn.edu/TBPA/treatment/managingsideeffects.pdf