PYRAZINAMIDE

PYRAZINAMIDe
(peer-a-zin'a-mide)
PZA, Tebrazid

Classifications: antibiotic; antituberculosis agent;
Therapeutic: antibiotic; antituberculosis
Pregnancy Category: C

Availability

500 mg tablets

Action

Pyrazinoic acid amide, analog of nicotinamide.

Therapeutic Effect

Bacteriostatic against Mycobacterium tuberculosis. Not used as sole agent against TB infection.

Uses

Short-term therapy of advanced tuberculosis before surgery and to treat patients unresponsive to primary agents (e.g., isoniazid, streptomycin).

Contraindications

Severe liver damage, acute gout; pregnancy (category C).

Cautious Use

History of gout or diabetes mellitus; impaired kidney function; alcoholism; history of peptic ulcer; acute intermittent porphyria, and lactation.

Route & Dosage

Tuberculosis
Adult: PO 15–35 mg/kg/d in 3–4 divided doses (max: 2 g/d)
Child: PO 20–40 mg/kg/d divided q12–24h (max: 2 g/d)

Administration

Oral

Discontinue drug if hepatic reactions (jaundice, pruritus, icteric sclerae, yellow skin) or hyperuricemia with acute gout (severe pain in great toe and other joints) occur.
Store at 15°–30° C (59°–86° F) in tightly closed container.

Adverse Effects (≥1%)

Body as a Whole: Active gout, arthralgia, lymphadenopathy. Urogenital: Difficulty in urination. CNS: Headache. Skin: Urticaria. Hematologic: Hemolytic anemia, decreased plasma prothrombin. GI: Splenomegaly, fatal hemoptysis, aggravation of peptic ulcer, hepatotoxicity, abnormal liver function tests. Metabolic: Rise in serum uric acid.

Diagnostic Test Interference

Pyrazinamide may produce a temporary decrease in 17-ketosteroids and an increase in protein-bound iodine.

Interactions

Drug: Increase in liver toxicity (including fatal hepatoxicity in when treating latent TB) with rifampin.

Pharmacokinetics

Absorption: Readily from GI tract. Peak: 2 h. Distribution: Crosses blood–brain barrier. Metabolism: In liver. Elimination: Slowly in urine. Half-Life: 9–10 h.

Nursing Implications

Assessment & Drug Effect

Observe and supervise closely. Patients should receive at least one other effective antituberculosis agent concurrently.
Examine patients at regular intervals and question about possible signs of toxicity: Liver enlargement or tenderness, jaundice, fever, anorexia, malaise, impaired vascular integrity (ecchymoses, petechiae, abnormal bleeding).
Hepatic reactions appear to occur more frequently in patients receiving high doses.
Lab tests: Obtain liver function tests (especially AST, ALT, serum bilirubin) prior to and at 2–4 wk intervals during therapy. Blood uric acid determinations are advised before, during, and following therapy.

Patient & Family Education

Report to physician onset of difficulty in voiding. Keep fluid intake at 2000 mL/d if possible.
Monitor blood glucose (diabetics) for possible loss of glycemic control.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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