probenecid

REMS

Prevention of recurrences of gouty arthritis.
Treatment of hyperuricemia secondary to thiazide therapy.
To increase and prolong serum levels of penicillin and related anti-infectives.

Action ⬆ ⬇

Inhibits renal tubular reabsorption of uric acid, thus promoting its renal excretion.

Therapeutic effects:

Reduction of serum uric acid levels.
Prolonged serum levels of penicillins and other related antibiotics.

Pharmacokinetics ⬆ ⬇

Absorption: Well absorbed following oral administration.

Distribution: Unknown.

Protein Binding: 75–95%.

Metabolism/Excretion: Mostly metabolized by the liver; 10% excreted unchanged in the urine.

Half-Life: 4–17 hr.

Time/Action Profile ⬆ ⬇

(effects on serum uric acid levels)

ROUTE	ONSET	PEAK	DURATION
PO	30 min	2–4 hr	8 hr

Contraind./Precautions ⬆ ⬇

Contraindicated in:

Hypersensitivity;
Chronic high-dose salicylate therapy;
Pedi: Children 2 yr.

Use Cautiously in:

Peptic ulcer;
Blood dyscrasias;
Uric acid kidney stones;
Renal impairment (dosage ↓ recommended; may not be effective if CCr ≤30 mL/min);
Lactation: Safety not established in breastfeeding.

Adv. Reactions/Side Effects ⬆ ⬇

Derm: flushing, rash

GI: nausea, vomiting, abdominal pain, diarrhea, hepatitis, sore gums

GU: uric acid stones, urinary frequency

Hemat: anemia, APLASTIC ANEMIA

Neuro: headache, dizziness

Interactions ⬆ ⬇

Drug-drug:

↑levels and risk of toxicity of acyclovir, allopurinol, barbiturates, benzodiazepines, cephalosporins, dapsone, methotrexate, NSAIDs, penicillamine, penicillins, rifampin, sulfonamides, sulfonylureas, or zidovudine.
Large doses of salicylates may ↓ uricosuric activity.

Route/Dosage ⬆ ⬇

PO (Adults and Children >50 kg): Hyperuricemia: 250 mg twice daily for 1 wk; ↑ to 500 mg twice daily, then may ↑ by 500 mg/day every 4 wk (not to exceed 3 g/day).Augmentation of penicillins/cephalosporins: 500 mg 4 times daily. Single-dose therapy of gonorrhea: 1 g with amoxicillin or penicillin.
PO (Children 2–14 yr and ≤50 kg): 25 mg/kg (700 mg/m²) initially; then 10 mg/kg (300 mg/m²) 4 times daily.

Availability ⬆ ⬇

(Generic available)

Tablets: 500 mg
In combination with: colchicine.

Assessment ⬆ ⬇

Gout: Assess involved joints for pain, mobility, and edema throughout course of therapy.
- Monitor intake and output ratios. Fluids should be encouraged to prevent urate stone formation (2000–3000 mL/day). Alkalinization of the urine with sodium bicarbonate, potassium citrate, or acetazolamide may also be used for this purpose.

Lab Test Considerations:

CBC, serum uric acid levels, and renal function should be monitored routinely during long-term therapy.
- Serum and urine uric acid determinations may be measured periodically when probenecid is used to treat hyperuricemia.

Implementation ⬆ ⬇

Probenecid therapy is not used to treat gouty arthritis but rather to prevent it. If acute attacks occur during therapy, probenecid is usually continued at full dose along with colchicine or NSAIDs.
PO: Administer with food or antacid to minimize gastric irritation.
- Gradual dosage reduction should be attempted if uric acid levels remain stable following 6 mo of therapy.

Patient/Family Teaching ⬆ ⬇

Instruct patient to take medication exactly as directed and not to discontinue without consulting health care professional. Irregular dosage schedules may cause elevation of uric acid levels and precipitate an acute gout attack.
Explain purpose of the medication to patients taking probenecid with penicillin.
Advise patient to follow recommendations of health care professional regarding weight loss, diet, and alcohol consumption.
Caution patient not to take aspirin or other salicylates, because they decrease the effects of probenecid.
Instruct patient to report nausea, vomiting, loss of appetite, abdominal pain, unusual bleeding or bruising, sore throat, fatigue, malaise, or yellowing of the skin or eyes promptly.
Rep: Advise females of reproductive potential to notify health care professional if breastfeeding is planned.

Evaluation/Desired Outcomes ⬆

Decrease in pain and swelling in affected joints and subsequent decrease in frequency of gout attacks. May require several mo of continuous therapy for maximum effects.
Decrease in serum uric acid levels.
Prolonged serum levels of penicillins and other related antibiotics.

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Pronunciation ⬇

Classifications ⬆ ⬇

Indications ⬆ ⬇