The white, oblong/capsule-shaped pill frequently searched as 6037 is almost universally a visual misreading of the imprint G 037 (where the uppercase letter “G” is read as the number “6”). This tablet is an immediate-release prescription combination analgesic containing Hydrocodone Bitartrate (10 mg) and Acetaminophen (325 mg), a generic equivalent to brand formulations such as Lortab 10/325 and Norco 10/325.
Pill Identification
Attribute – Specification
- Active Ingredients – Hydrocodone Bitartrate, USP (10 mg) / Acetaminophen, USP (325 mg)
- Imprint – G 037 (or misread as 6037) on one side; score line on the reverse
- Color & Shape – White, oblong / capsule-shaped, scored tablet
- Size – Approximately 15 mm to 16 mm
- Manufacturer / Marketer – Vintage Pharmaceuticals / Qualitest Pharmaceuticals (Endo) / Glenmark
- Drug Class – Opioid analgesic / Non-opioid antipyretic-analgesic combination
- Controlled Substance Schedule – DEA Schedule II (C-II)
Mechanism of Action
This fixed-dose combination provides analgesia through two complementary, synergistic mechanisms:
Hydrocodone (Opioid Agonism):
- Receptor Activation: Hydrocodone is a semi-synthetic opioid agonist that selectively binds to (mu)-opioid receptors in the central nervous system (CNS) and spinal cord.
- Intracellular Cascades: Receptor stimulation activates inhibitory G-proteins, reducing intracellular cAMP, closing presynaptic voltage-gated calcium channels, and opening postsynaptic inwardly rectifying potassium channels.
- Nociceptive Blockade: This hyperpolarizes neuronal membranes, inhibiting the presynaptic release of excitatory neurotransmitters (such as substance P and glutamate) and blunting the transmission and emotional perception of pain signals in ascending spinal pathways.
Acetaminophen (Central Cyclooxygenase & Serotonergic Modulation):
- Central Prostaglandin Inhibition: Acetaminophen acts primarily in the CNS to inhibit cyclooxygenase enzyme variants, suppressing central prostaglandin synthesis.
- Descending Pain Pathways: It is metabolized in nervous tissue to AM404, which modulates cannabinoid and vanilloid receptors while enhancing descending serotonergic inhibitory pathways, raising the systemic pain threshold and lowering fever.
Indications and Clinical Uses
- Moderate to Severe Acute Pain: Indicated for the management of acute pain severe enough to require an opioid analgesic (such as post-surgical recovery, severe musculoskeletal injuries, or dental surgery trauma) when alternative non-opioid options (like NSAIDs or APAP monotherapy) are ineffective, contraindicated, or poorly tolerated.
Dosage and Administration
- Prescribing guidelines mandate initiating treatment at the lowest effective dose for the shortest duration necessary.
- Standard Adult Dosing: 1 tablet orally every 4 to 6 hours as needed for pain.
- Maximum Daily Ceiling:
- Tablet Limit: Typically no more than 6 tablets per 24 hours (providing a maximum of 60 mg hydrocodone and 1,950 mg acetaminophen).
- Acetaminophen Limit: Total cumulative daily intake of acetaminophen from all sources (including OTC cold medicines) must not exceed 4,000 mg/24 hours (clinical guidelines frequently advise keeping daily intake under 3,000 mg to protect hepatic function).
- Administration: Swallow whole with water. May be taken with food or milk to minimize potential gastrointestinal upset.
- Tapering & Discontinuation: When used continuously for more than a few days, the medication must be gradually tapered under clinical supervision to avoid precipitating acute opioid withdrawal symptoms.
Side Effects
Common Adverse Reactions:
- Central Nervous System: Somnolence/drowsiness, dizziness, lightheadedness, sedation, headache
- Gastrointestinal: Constipation (often requiring prophylactic stool softeners), nausea, vomiting, xerostomia (dry mouth)
- Dermatologic / Autonomic: Pruritus (itching), sweating (hyperhidrosis), peripheral vasodilation/flushing
Serious Adverse Reactions:
- Life-Threatening Respiratory Depression: Severe reduction in respiratory rate, tidal volume, apnea, or respiratory arrest.
- Acute Hepatotoxicity: Severe centrilobular liver necrosis, acute liver failure, or death associated with acetaminophen overdose.
- Severe Hypotension & Syncope: Significant drops in blood pressure, orthostatic hypotension, or bradycardia.
- Serotonin Syndrome: When co-administered with serotonergic agents (manifesting with tremor, hyperreflexia, clonus, fever, and agitation).
- Severe Cutaneous Adverse Reactions (SCAR): Rare, life-threatening skin reactions (Stevens-Johnson syndrome [SJS], Toxic Epidermal Necrolysis [TEN]) triggered by acetaminophen hypersensitivity.
Key Drug Interactions
- CNS Depressants & Alcohol: Concomitant administration with benzodiazepines, tranquilizers, sedatives, muscle relaxants, or alcohol produces profound additive CNS and respiratory depression, frequently leading to coma or fatal overdose.
- CYP3A4 Inhibitors & Inducers: Hydrocodone is partly metabolized via cytochrome P450 CYP3A4. Strong CYP3A4 inhibitors (e.g., ketoconazole, erythromycin) raise hydrocodone plasma levels, increasing overdose risks; CYP3A4 inducers (e.g., rifampin, carbamazepine) decrease efficacy and may precipitate withdrawal.
- CYP2D6 Inhibitors: Inhibitors of CYP2D6 (e.g., fluoxetine, paroxetine) alter the metabolic conversion of hydrocodone to its more active metabolite, hydromorphone, affecting analgesic response.
- Other Acetaminophen Products: Concomitant ingestion of over-the-counter cough/flu medications or other prescription combinations containing acetaminophen creates a severe risk of cumulative hepatotoxicity.
- MAO Inhibitors: Opioids should not be administered within 14 days of taking monoamine oxidase inhibitors (MAOIs).
Boxed Warnings and Precautions
- Addiction, Abuse, and Misuse: Hydrocodone carries a high potential for opioid use disorder, physical dependence, misuse, and diversion.
- Life-Threatening Respiratory Depression: Fatal respiratory depression can occur even at therapeutic doses, with the greatest vulnerability during therapy initiation or dose escalation.
- Hepatotoxicity Risk: Overdosing acetaminophen is a leading cause of acute liver failure, occasionally requiring liver transplantation or causing death.
- Accidental Pediatric Ingestion: Accidental ingestion of even a single tablet by a child can cause fatal opioid poisoning.
- Neonatal Opioid Withdrawal Syndrome (NOWS): Prolonged maternal use during pregnancy can lead to life-threatening withdrawal in the newborn requiring specialized neonatal intensive care.
- Contraindications: Significant respiratory depression; acute or severe bronchial asthma in unmonitored settings; known or suspected gastrointestinal obstruction, including paralytic ileus; known hypersensitivity to hydrocodone, acetaminophen, or tablet excipients.