Comparative Pharmacology
Head-to-head clinical analysis: DARVOCET A500 versus ULTRACET.
Peer-Reviewed Evidence
Head-to-head clinical analysis: DARVOCET A500 versus ULTRACET.
DARVOCET A500 vs ULTRACET
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Combination analgesic: acetaminophen inhibits cyclooxygenase (COX) and modulates endocannabinoid system; propoxyphene is a mu-opioid receptor agonist.
ULTRACET is a combination of tramadol (a centrally acting opioid agonist) and acetaminophen (a centrally acting analgesic with antipyretic effects). Tramadol binds to mu-opioid receptors and inhibits norepinephrine and serotonin reuptake. Acetaminophen's mechanism is not fully understood but involves inhibition of cyclooxygenase (COX) enzymes in the central nervous system.
One tablet (500 mg acetaminophen, 100 mg propoxyphene napsylate) orally every 4 hours as needed for pain; maximum 6 tablets per day.
1-2 tablets (37.5 mg tramadol/325 mg acetaminophen per tablet) orally every 4-6 hours as needed for pain, not to exceed 8 tablets per day.
None Documented
None Documented
Propoxyphene: 6-12 hours (terminal, prolonged in elderly, hepatic impairment, or overdose). Acetaminophen: 2-3 hours (terminal, prolonged in hepatic impairment or overdose).
Tramadol: 5.1 ± 0.9 hours (range 4-6 hours) for the parent drug; the active M1 metabolite has a half-life of 6.7 ± 1.7 hours. In hepatic impairment, tramadol half-life increases ~2-3 fold. Acetaminophen: 2-3 hours (range 1.25-3 hours); prolonged in overdose.
Propoxyphene: ~20-25% renal as unchanged drug, ~35% as norpropoxyphene, ~20% biliary/fecal. Acetaminophen: ~2-4% renal unchanged, ~85% as glucuronide and sulfate conjugates, ~5% as cysteine and mercapturate conjugates.
Tramadol and its metabolites are primarily excreted via the kidneys (approximately 90% of the dose), with about 30% excreted as unchanged drug and 60% as metabolites. Approximately 10% is excreted in feces. Acetaminophen is primarily conjugated in the liver and excreted renally as glucuronide (60-80%) and sulfate (20-30%) conjugates, with about 5% excreted unchanged.
Category C
Category C
Opioid Analgesic Combination
Opioid Analgesic Combination