The white, oblong (capsule-shaped) pill debossed with 377 on one side and plain on the reverse is an immediate-release oral prescription medication containing Tramadol Hydrochloride (50 mg), a centrally acting synthetic opioid analgesic.
Pill Identification
Attribute – Specification
- Active Ingredient – Tramadol Hydrochloride, USP (50 mg)
- Imprint – 377 on one side; plain on the reverse
- Color & Shape – White to off-white, oblong / capsule-shaped, film-coated
- Size – Approximately 13 mm
- Primary Distributors/Manufacturers – Sun Pharmaceutical Industries, Inc. / Caraco Pharmaceutical Laboratories
- Drug Class – Centrally acting synthetic opioid analgesic / Dual reuptake inhibitor
- Controlled Substance Schedule – DEA Schedule IV (C-IV)
- (Note: While some distinct products share portions of the numerical sequence, such as quetiapine 50 mg stamped “54 377” or hydrocodone/acetaminophen stamped “M377”, the isolated “377” imprint on a plain white capsule-shaped tablet corresponds to generic 50 mg tramadol hydrochloride).
Mechanism of Action
Tramadol exhibits a unique, dual mechanism of action combining opioid and non-opioid pain-relieving pathways:
- Weak Opioid Agonism: Tramadol itself is a weak opioid receptor agonist. It is extensively metabolized in the liver via CYP2D6 into its active metabolite, desmethyltramadol (M1). M1 binds to opioid receptors with approximately 200 to 300 times higher affinity than the parent drug, inhibiting ascending nociceptive pain signals.
- Monoamine Reuptake Inhibition: Independent of opioid receptor activation, tramadol weakly inhibits the neuronal reuptake of serotonin (5-HT) and norepinephrine (NE). This increases neurotransmitter levels in the spinal cord, enhancing descending inhibitory pain pathways.
Indications and Clinical Uses
- Moderate to Moderately Severe Pain: Indicated for adults requiring an opioid analgesic when alternative non-opioid medications (e.g., acetaminophen, NSAIDs) are inadequate, not tolerated, or contraindicated.
- Postoperative & Musculoskeletal Pain: Frequently utilized for post-surgical trauma, acute injury, or osteoarthritis flares.
Dosage and Administration
- Dosing must be individualized to the lowest effective dose for the shortest duration necessary.
- Standard Adult Dosing: 50 mg to 100 mg orally every 4 to 6 hours as needed for acute pain.
- Maximum Daily Dose: Do not exceed 400 mg per day (or 300 mg per day in elderly patients aged 75 and older).
- Titration for Chronic Conditions: To improve tolerability and reduce initial nausea/dizziness, treatment is often initiated at 25 mg/day (or 50 mg/day) and titrated by 50 mg every 3 days up to target maintenance.
- Renal Impairment: In patients with severe renal impairment , increase the dosing interval to every 12 hours, with a maximum daily limit of 200 mg.
- Hepatic Impairment: In severe hepatic impairment (cirrhosis), the recommended dose is 50 mg every 12 hours.
- Discontinuation: If taken continuously for more than a few days, gradually taper the dosage to prevent withdrawal symptoms.
Side Effects
Common Adverse Reactions:
- Gastrointestinal: Nausea (up to 40%), constipation (up to 46%), vomiting, dry mouth, abdominal discomfort
- Central Nervous System: Dizziness, lightheadedness, drowsiness/somnolence, headache, insomnia, tremor
- Systemic / Autonomic: Sweating (hyperhidrosis), pruritus, flushing
Serious Adverse Reactions:
- Seizures: Can occur even at recommended therapeutic doses, with heightened risk at doses exceeding 400 mg/day.
- Life-Threatening Respiratory Depression: Hypoventilation, slow/shallow breathing, or apnea.
- Serotonin Syndrome: High risk when co-administered with serotonergic agents; manifests with clonus, tremor, hyperreflexia, hyperthermia, rigidity, and autonomic instability.
- Adrenal Insufficiency & Orthostatic Hypotension: Decreased cortisol production or sudden drops in blood pressure upon standing.
Key Drug Interactions
- Serotonergic Agents: Concomitant use with SSRIs (e.g., fluoxetine, sertraline), SNRIs (e.g., duloxetine, venlafaxine), tricyclic antidepressants, triptans, or linezolid significantly increases the risk of Serotonin Syndrome.
- MAO Inhibitors: Strictly contraindicated during or within 14 days of monoamine oxidase inhibitor (MAOI) therapy due to risk of fatal serotonin toxicity and hypertensive crises.
- CYP2D6 & CYP3A4 Inhibitors/Inducers:
- CYP2D6 Inhibitors (e.g., bupropion, fluoxetine, paroxetine, quinidine) reduce conversion to the active analgesic metabolite M1, lowering pain relief while raising tramadol levels and seizure risk.
- CYP3A4 Inhibitors (e.g., ketoconazole, erythromycin) increase exposure to tramadol and M1.
- CNS Depressants and Alcohol: Co-ingestion with benzodiazepines, barbiturates, muscle relaxants, or alcohol leads to profound sedation, severe respiratory depression, coma, or fatal overdose.
Boxed Warnings and Contraindications
- Addiction, Abuse, and Misuse: As a Schedule IV controlled substance, tramadol carries risks of addiction, abuse, and misuse that can lead to overdose and death.
- Life-Threatening Respiratory Depression: Serious, life-threatening, or fatal respiratory depression may occur, particularly upon initiation or dose escalation.
- Ultra-Rapid CYP2D6 Metabolism: Individuals who are CYP2D6 ultra-rapid metabolizers convert tramadol into its active M1 metabolite much faster, leading to dangerously high opioid blood levels and life-threatening respiratory arrest.
- Contraindications:
- Pediatric Restrictions: Contraindicated in all children younger than 12 years of age, and in adolescents under 18 years following tonsillectomy and/or adenoidectomy.
- Significant respiratory depression or acute/severe bronchial asthma in unmonitored settings.
- Known or suspected gastrointestinal obstruction (including paralytic ileus).
- Concurrent use of or within 14 days of MAO inhibitors.