What is Antidol (tramadol)?

What is Antidol (Tramadol)?

Antidol is a brand name for tramadol, a centrally acting synthetic opioid analgesic that works through a dual mechanism as a weak μ-opioid receptor agonist and an inhibitor of norepinephrine and serotonin reuptake. 1, 2

Pharmacology and Mechanism of Action

Tramadol has unique properties that distinguish it from traditional opioids:

• Dual mechanism of action:

  • Binds to μ-opioid receptors (approximately one-tenth the potency of morphine)
  • Inhibits reuptake of norepinephrine and serotonin 1, 2

• Metabolism:

  • Metabolized in the liver to its active M1 metabolite (O-demethyl tramadol)
  • The M1 metabolite has higher affinity for opioid receptors than the parent drug 2
  • Metabolism is influenced by CYP2D6 enzyme, leading to variable response between patients 3

• Pharmacokinetics:

  • Oral bioavailability: approximately 75%
  • Peak plasma concentration: 2-3 hours after administration
  • Half-life: 6-7 hours for tramadol, 7-9 hours for M1 metabolite
  • Steady-state plasma concentrations achieved within two days with four-times-daily dosing 1, 2

Clinical Uses

Tramadol is primarily used for:

• Moderate to moderately severe chronic pain
• Second or third-line agent when first-line therapies (acetaminophen, NSAIDs) fail to provide adequate relief
• Various chronic pain conditions including osteoarthritis 1

Dosing Recommendations

• Standard dosing: 50-100 mg every 4-6 hours as needed
• Maximum daily dose: 400 mg for most adults, 300 mg/day for patients over 75 years
• Initial titration: Start with 50 mg once daily, increase by 50 mg every 3 days as tolerated
• Special populations:
  • Elderly (>65 years): Start at lower end of dosing range
  • Renal impairment (CrCl <30 mL/min): Increase dosing interval to 12 hours, maximum 200 mg/day
  • Hepatic impairment: 50 mg every 12 hours for patients with cirrhosis 1

Safety Profile

Tramadol offers some advantages over traditional opioids:

• Lower risk of respiratory depression
• Lower dependence potential in short-term use
• Less constipation than equianalgesic doses of strong opioids 1, 3

However, important safety concerns include:

• Common side effects: Nausea, vomiting, constipation, sedation, dizziness, dry mouth
• Serious risks:
  • Serotonin syndrome (especially when combined with other serotonergic medications)
  • Seizures (through inhibition of nitric oxide, serotonin reuptake, and effects on GABA receptors)
  • Contraindicated with MAOIs
  • Potential for abuse and dependence (though lower than traditional opioids) 1, 4

Monitoring Recommendations

When prescribing tramadol, clinicians should:

• Use an "opioid patient-provider agreement" before initiating therapy
• Monitor through urine drug testing, pill counts, and prescription drug monitoring programs
• Educate patients about safe storage and potential overdose
• Consider providing a naloxone rescue kit
• Plan for appropriate tapering when discontinuing (reductions of 50 mg every 3 days to minimize withdrawal) 1

Important Distinctions

• Tramadol is approximately one-tenth as potent as morphine
• Its analgesic effect begins within one hour and peaks in 2-3 hours
• The dual mechanism provides a unique analgesic profile with potentially fewer respiratory effects than traditional opioids 1, 2, 5