When identifying a white oval (or capsule-shaped/oblong) pill marked with “5500” (often read as “5 500”, “S 500”, or “5-500”), pill identification databases and clinical references point to two primary possibilities depending on the exact debossing:
- Acetaminophen 500 mg (“S 500” / “P 500” / “500” White Oval): An over-the-counter (OTC) extra-strength non-opioid analgesic and antipyretic.
- Hydrocodone Bitartrate and Acetaminophen 5 mg / 500 mg (“5-500” White Oval): A classic prescription opioid combination analgesic (such as legacy generic formulations or brand equivalents like Lortab 5/500 or Vicodin 5/500). (Note: In 2014, the FDA mandated limiting acetaminophen in prescription combination products to per dosage unit to prevent liver toxicity, making 5/500 tablets a legacy formulation).
Below is the detailed profile for both major medications.
Primary Match 1: Acetaminophen 500 mg (“S 500” / “500” White Oval / Caplet)
Pill Identification
Attribute – Specification
- Active Ingredient – Acetaminophen, USP (500 mg)
- Imprint – S 500, P 500, or 500 on one side
- Color & Shape – White, oval / capsule-shaped (caplet), film-coated
- Availability – Over-the-counter (OTC)
- Drug Class – Non-opioid, non-salicylate analgesic and antipyretic
Mechanism of Action
- Central Prostaglandin Inhibition: Acetaminophen acts primarily in the central nervous system (CNS) by inhibiting cyclooxygenase enzyme variants in neural tissue, suppressing prostaglandin synthesis.
- Thermoregulatory Reset: Inhibits production in the preoptic area of the anterior hypothalamus, adjusting the hypothalamic set-point to promote vasodilation and sweating for fever reduction.
- Cannabinoid & Serotonergic Pathway Modulation: Metabolized into AM404, which indirectly activates cannabinoid receptors and reinforces descending serotonergic inhibitory pathways in the spinal cord.
Dosage and Administration
- Adults and Adolescents (12+ years): 500 mg to 1,000 mg (1 to 2 caplets) orally every 4 to 6 hours as needed.
- Maximum Daily Dose: Do not exceed 3,000 mg to 4,000 mg in 24 hours from all combined sources.
- Duration: Limit use to no more than 10 days for pain or 3 days for fever unless directed by a physician.
Side Effects & Warnings
- Hepatotoxicity Risk: Excessive dosage, chronic heavy alcohol intake, or combining multiple acetaminophen-containing products can cause severe centrilobular liver necrosis and acute liver failure.
- Severe Skin Reactions: Rare occurrences of Stevens-Johnson syndrome (SJS) and Toxic Epidermal Necrolysis (TEN).
- Overdose Antidote: In acute overdose situations, prompt administration of acetylcysteine (NAC) within 8 hours prevents fatal hepatic injury.
Primary Match 2: Hydrocodone / Acetaminophen 5 mg / 500 mg (“5-500” Legacy Formulation)
Pill Identification
Attribute – Specification
- Active Ingredients – Hydrocodone Bitartrate (5 mg) / Acetaminophen (500 mg)
- Imprint Variations – 5-500, Watson 500, or MLB 125 5-500
- Color & Shape – White, oval / oblong / capsule-shaped tablet
- Drug Class – Opioid agonist / Non-opioid analgesic combination
- Controlled Substance Schedule – DEA Schedule II (C-II)
Mechanism of Action
- Hydrocodone (Opioid Agonism): Semisynthetic opioid that selectively binds to (mu)-opioid receptors in the brain and spinal cord. Receptor activation inhibits adenylyl cyclase, closes presynaptic voltage-gated calcium channels, and opens postsynaptic potassium channels. This hyperpolarizes neurons and blocks ascending nociceptive pain signals.
- Acetaminophen (Synergistic Analgesia): Provides central analgesia and antipyresis, complementing opioid receptor stimulation to lower overall pain transmission.
Indications and Clinical Uses
- Moderate to Moderately Severe Pain: Management of acute pain (such as acute musculoskeletal trauma or post-surgical recovery) when non-opioid monotherapies are insufficient.
Dosage and Administration
- Adult Dosing (Legacy Guidance): 1 tablet orally every 4 to 6 hours as needed for pain.
- Maximum Daily Dose: Generally limited to a maximum of 6 to 8 tablets per day, constrained by the 4,000 mg daily ceiling for acetaminophen.
- Tapering: Discontinuation after regular use requires a gradual reduction to prevent acute opioid withdrawal.
Side Effects
- Common: Drowsiness, lightheadedness, dizziness, sedation, nausea, vomiting, and constipation.
- Serious: Severe respiratory depression (hypoventilation/apnea), severe hypotension, acute liver failure (from APAP toxicity), and serotonin syndrome (when combined with serotonergic medications).
Boxed Warnings & Precautions
- Addiction, Abuse, and Misuse: High potential for opioid dependence, substance use disorder, and overdose.
- Life-Threatening Respiratory Depression: Severe, fatal respiratory arrest may occur even at therapeutic doses.
- Concomitant Use with CNS Depressants: Co-ingestion with alcohol, benzodiazepines, or other sedatives exponentially increases the risk of fatal respiratory failure.
- Hepatotoxicity: High doses of acetaminophen are a leading cause of acute liver failure.