Dosing and uses of Benemid (probenecid)
Adult dosage forms and strengths
tablet
- 500mg
Gout
250 mg PO twice daily for 1 week; increase to 500 mg PO twice daily to 2 g/day maximum with dosage increases of 500 mg q4weeks
If gout attacks do not occur for 4 months and uric acid levels are within normal may reduce dose by 500 mg q6monts
Prolong Penicillin Serum Levels
500 mg PO four times daily
Pelvic Inflammatory Disease
1 g PO with 2 g cefoxitin IM as single dose
Gonorrhea
1 g PO with 2 g cefoxitin IM as single dose
Renal Impairment
CrCl<30 mL/min: Avoid use
Pediatric dosage forms and strengths
tablet
- 500mg
Prolong Penicillin Serum Levels
<2 years old
- Contraindicated
>2 years old
- <45 kg: Load 25 mg/kg PO once with PCN; increase to 40 mg/kg/day PO divided q6hr; not to exceed 500 mg/dose
- >45 kg: 500 mg PO four times daily
Gonorrhea
<50 kg
- Safety and efficacy not established
>50 kg
- 1 g PO with 2 g cefoxitin IM as single dose
Benemid (probenecid) adverse (side) effects
1-10%
Headache
Nausea
Vomiting
Loss of appetite
GI upset
Rash
Flushing
Dizziness
Fever
Aplastic anemia
Hemolytic anemia
Leukopenia
Renal calculi
Nephrotic syndrome (rare)
Exacerbation of gout
Gouty arthritis
Hepatic necrosis (rare)
Warnings
Contraindications
<2 years
Uric acid kidney stones, acute gouty arthritis
Hypersensitivity
Blood dyscrasias
Small or large dose aspirin therapy
Cautions
PUD, renal impairment (CrCl <50 mLmin)
Do NOT administer for acute gouty attacks; if acute precipitation occurs during treatment may continue therapy
Alkalinize urine to avoid renal calculi
Use caution in patients with G6PD deficiency; may increase risk for hemolytic anemia
Discontinue if allergic reaction occurs
Use caution in patients with peptic ulcer disease
May cause exacerbation of acute gouty attack
Monotherapy may not be effective in patients with a creatinine clearance <30 mL/min
May increase serum concentration of methetrexate (avoid concomitant administration)
Use of probenecid with penicillin in patients with with renal insufficiency is not recommended
Salicylates may reduce the therapeutic effects of probenecid (effect may be pronounced with high chronic doses
Pregnancy and lactation
Pregnancy category: B
Lactation: Not known if distributed into breast milk, use with caution
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Benemid (probenecid)
Mechanism of action
(Uricosuric) inhibits tubular reabsorption of urate; increasing uric acid excretion
Also inhibits tubular secretion of weak organic acids like PCNs & cephalosporins
Pharmacokinetics
Half-Life: 3-17 hr
Onset: 2 hr (effect on penicillin levels)
Peak Plasma Time: 2-4 hr
Bioavailability: >90%
Protein Bound: 85-95% (albumin)
Metabolism: Liver
Metabolites: hydroxylated metabolites, N-despropyl metabolite, probenecid acylglucuronide
Excretion: Urine
