Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
AMBENYL vs ACETAMINOPHEN AND HYDROCODONE BITARTRATE
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
AMBENYL is a combination product containing codeine (opioid agonist) and bromodiphenhydramine (antihistamine). Codeine binds to mu-opioid receptors in the CNS, inhibiting ascending pain pathways and altering pain perception; bromodiphenhydramine antagonizes histamine H1 receptors, producing antitussive and sedative effects.
Acetaminophen: analgesic and antipyretic effects via inhibition of cyclooxygenase (COX) and activation of descending serotonergic pathways; central action. Hydrocodone: mu-opioid receptor agonist; activates G-protein coupled receptors to modulate pain perception and emotional response.
Cough suppression,Symptomatic relief of cough associated with colds or allergies
Moderate to moderately severe pain,Cough suppression (hydrocodone; off-label)
Each 5 m L contains codeine phosphate 10 mg and diphenhydramine hydrochloride 12.5 mg. Adults: 10 m L (2 teaspoonfuls) orally every 4-6 hours as needed; maximum 40 m L per day.
1-2 tablets (containing 5-10 mg hydrocodone and 300-325 mg acetaminophen) orally every 4-6 hours as needed for pain; maximum 8 tablets per day.
Codeine: 2.5-3.5 h (terminal) with CYP2D6 poor metabolizers up to 6 h. Guaifenesin: 1-2 h.
Acetaminophen: 2-3 hours in adults; prolonged in hepatic impairment (up to 5 hours). Hydrocodone: 3.8-4.5 hours (range 3-5 hours) in healthy adults; prolonged in elderly or hepatic/renal impairment. Clinical context: repeated dosing may require extended intervals in renal impairment.
Codeine is metabolized via CYP2D6 to morphine (active), CYP3A4 to norcodeine, and to a lesser extent via glucuronidation; bromodiphenhydramine is metabolized via CYP450 enzymes, primarily CYP2D6.
Acetaminophen: primarily via glucuronidation (UGT1A1, UGT1A6, UGT1A9) and sulfation; minor CYP2E1 oxidation to NAPQI (toxic metabolite). Hydrocodone: CYP3A4 and CYP2D6; N-demethylation to norhydrocodone; O-demethylation to hydromorphone (CYP2D6).
Renal: 60% unchanged codeine, 20% codeine-6-glucuronide; biliary/fecal: 20% as metabolites. Guaifenesin: renal 95% as unchanged drug and metabolites.
Acetaminophen: primarily renal excretion of conjugated metabolites (glucuronide and sulfate) with approximately 5% excreted unchanged. Hydrocodone: renal excretion as unchanged drug and metabolites (O-demethylated and N-demethylated); total renal excretion accounts for about 60-70% of dose (parent and metabolites). Biliary/fecal elimination is minimal.
Codeine: 7-25% (albumin). Guaifenesin: negligible.
Acetaminophen: 10-25% bound, nonspecific binding to albumin. Hydrocodone: 25-50% bound, primarily to albumin and alpha-1-acid glycoprotein.
Codeine: 3-6 L/kg (extensive tissue distribution). Guaifenesin: 1-2 L/kg.
Acetaminophen: 0.8-1.0 L/kg, indicating distribution into total body water; clinically relevant for loading dose calculations. Hydrocodone: 3.0-4.0 L/kg, suggesting extensive tissue distribution; higher Vd may require higher loading doses but has no clinical target.
Codeine: oral 90% (first-pass metabolism). Guaifenesin: oral 100% (well absorbed).
Acetaminophen: oral bioavailability 85-95% (first-pass metabolism minimal). Hydrocodone: oral bioavailability about 25-45% due to first-pass hepatic metabolism; significant interindividual variability.
GFR 30-50 m L/min: use with caution, reduce dose by 25-50% and monitor for CNS depression. GFR <30 m L/min: avoid use or use with extreme caution; codeine accumulation risk.
GFR 10-50 m L/min: administer every 6 hours; GFR <10 m L/min: administer every 8 hours; avoid in severe impairment due to acetaminophen metabolite accumulation.
Child-Pugh A: no adjustment needed. Child-Pugh B: use with caution, consider 50% dose reduction. Child-Pugh C: avoid use.
Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50% or extend interval; Child-Pugh C: use with caution, avoid if possible, consider alternative therapy.
Not recommended for children under 6 years. Children 6-12 years: 5 m L (1 teaspoonful) orally every 4-6 hours; maximum 20 m L per day. Children >12 years: adult dosing.
Dosing based on hydrocodone component: 0.1-0.2 mg/kg/dose every 4-6 hours; maximum daily acetaminophen limit: 75 mg/kg/day; not recommended for children <2 years.
Initiate at 5 m L every 6 hours due to increased sensitivity to anticholinergic and CNS depressant effects; monitor for confusion, sedation, and urinary retention.
Initiate at lowest effective dose, typically 1 tablet (2.5-5 mg hydrocodone) every 6 hours; monitor for respiratory depression and acetaminophen toxicity; avoid in frail elderly with hepatic impairment.
Risk of respiratory depression, especially in children; risk of opioid addiction, abuse, and misuse; risk of neonatal opioid withdrawal syndrome with prolonged use during pregnancy; CYP2D6 ultra-rapid metabolizers may convert codeine to morphine at higher rates, leading to fatal respiratory depression.
Addiction, abuse, and misuse; life-threatening respiratory depression; accidental ingestion of acetaminophen; neonatal opioid withdrawal syndrome; interaction with alcohol; risk of medication errors.
Respiratory depression; use in children <12 years contraindicated; risk of opioid-induced hyperalgesia; central nervous system depression; sedation; constipation; urinary retention; hypotension; anticholinergic effects; potential for misuse, abuse, and addiction; serotonin syndrome if used with other serotonergic drugs; adrenal insufficiency; risk of severe hypotension in volume-depleted patients; interactions with CNS depressants.
Hepatotoxicity from acetaminophen overdose; respiratory depression; increased intracranial pressure; CNS depression; elderly/debilitated patients; renal impairment; opioid-induced hyperalgesia; serotonin syndrome; interaction with CNS depressants; risk of adrenal insufficiency; severe hypotension; use in patients with gastrointestinal obstruction; convulsion risk; severe hepatic impairment; urinary retention; acute abdominal conditions; hypothyroidism; prostatic hypertrophy; adrenocortical insufficiency; pregnancy/lactation; pediatric use; geriatric use; renal impairment; hepatic impairment.
Children <12 years; post-operative management in children <18 years after tonsillectomy/adenoidectomy; respiratory depression; acute or severe bronchial asthma; known hypersensitivity to codeine, bromodiphenhydramine, or any component; concurrent use of monoamine oxidase inhibitors (MAOIs) or within 14 days; gastrointestinal obstruction; paralytic ileus.
Hypersensitivity to acetaminophen or hydrocodone; significant respiratory depression; acute or severe bronchial asthma; upper airway obstruction; known or suspected gastrointestinal obstruction; paralytic ileus; concomitant use of monoamine oxidase inhibitors (MAOIs) or within 14 days; severe hepatic impairment (acetaminophen toxicity risk); acute alcoholism.
Zolpidem absorption is delayed and reduced when taken with food, especially high-fat meals. To achieve rapid onset of sleep, take on an empty stomach. Avoid grapefruit juice as it may increase zolpidem levels.
Avoid alcohol consumption during therapy; ethanol increases acetaminophen hepatotoxicity risk and enhances CNS depression. Grapefruit juice may inhibit CYP2D6 (minor effect) but no significant clinical interaction. No other specific food restrictions.
FDA Pregnancy Category C. First trimester: Limited data; potential for fetal malformations (cleft palate, cardiac defects) based on animal studies with high-dose antihistamines. Second and third trimesters: Risk of neonatal respiratory depression, irritability, and withdrawal if used near term. Avoid in third trimester due to risk of premature closure of ductus arteriosus (codeine component).
First trimester: Acetaminophen considered low risk; hydrocodone is a pregnancy category C drug. Data from retrospective studies suggest a small increased risk of certain congenital malformations (e.g., neural tube defects, cleft palate) with first trimester opioid use, but absolute risk is low. Second trimester: Low risk as above. Third trimester: Prolonged use of hydrocodone can cause neonatal opioid withdrawal syndrome (NOWS); acetaminophen is safe. Use only if benefit outweighs risk.
Codeine is excreted in breast milk (M/P ratio ~2.5); risk of neonatal opioid toxicity (CNS depression). Diphenhydramine may inhibit lactation and cause drowsiness in infant. Contraindicated during breastfeeding due to possible severe adverse reactions in neonates.
Acetaminophen excretion in breast milk is low (M/P ratio ~0.9). Hydrocodone is excreted in small amounts (M/P ratio ~2.1). The relative infant dose is estimated to be 2.5-3.5% of maternal weight-adjusted dose for hydrocodone. Monitor infant for sedation and respiratory depression. Consider benefit to mother and potential neonatal opioid withdrawal if used chronically.
No established safe dose during pregnancy; avoid use. If unavoidable, use lowest effective dose for shortest duration. Pharmacokinetic changes (increased clearance, volume of distribution) may require dose adjustment, but due to risks, alternative therapy is recommended.
During pregnancy, increased plasma volume and enhanced hepatic clearance may reduce serum concentrations of both drugs. However, dosing adjustments are not routinely recommended due to risk of undertreatment. Use the lowest effective dose of hydrocodone for the shortest duration. For acetaminophen, maximum daily dose should not exceed 3000 mg to avoid hepatotoxicity.
Ambien (zolpidem) is a non-benzodiazepine sedative-hypnotic used primarily for short-term insomnia. Avoid co-administration with alcohol or other CNS depressants. Use the lowest effective dose, especially in elderly patients, due to increased risk of falls and cognitive impairment. Monitor for complex sleep behaviors (e.g., sleep-driving). Tablet should be taken immediately before bedtime, not with or after a meal to avoid delayed onset.
Acetaminophen-hydrocodone is contraindicated in severe respiratory depression, acute or severe bronchial asthma, and known hypersensitivity. Monitor for respiratory depression, especially in elderly or debilitated patients. Avoid use with other acetaminophen-containing products to prevent hepatotoxicity. Hydrocodone is a prodrug metabolized by CYP2D6 to hydromorphone; CYP2D6 ultrarapid metabolizers may experience toxicity. Use with caution in patients with head injury, increased intracranial pressure, or severe hepatic impairment. Naloxone is the reversal agent for opioid effects; acetylcysteine for acetaminophen overdose.
Take zolpidem exactly as prescribed, only when you have at least 7-8 hours to devote to sleep.,Do not take zolpidem with alcohol or other sedatives as this can cause severe drowsiness and dangerous side effects.,Avoid driving or operating machinery the morning after taking zolpidem, as it may cause drowsiness, dizziness, or impaired coordination.,Report any unusual behaviors during sleep, such as walking, eating, or driving, to your doctor immediately.,Do not crush, chew, or split the extended-release tablets; swallow them whole.
Take exactly as prescribed; do not increase dose or frequency without consulting your doctor.,Avoid alcohol and other CNS depressants (e.g., benzodiazepines, sedatives) as they increase risk of severe drowsiness and respiratory depression.,Do not exceed 4000 mg of acetaminophen per day from all sources; check labels of other medications.,This medication may cause dizziness or drowsiness; avoid driving or operating heavy machinery until you know how it affects you.,Store securely out of reach of others, especially children, as misuse can cause overdose and death.,Do not stop abruptly; withdrawal may occur. Taper under medical supervision.,Contact emergency if you experience trouble breathing, extreme drowsiness, or signs of allergic reaction.,Report any history of substance abuse, as this medication has abuse potential.
No interactions on record
"Hydrocodone, an opioid agonist, and scopolamine, an anticholinergic agent, both exhibit central nervous system (CNS) depressant effects. When co-administered, their combined activity can lead to additive CNS depression, resulting in enhanced sedation, respiratory depression, and cognitive impairment. This interaction may also increase the risk of constipation and urinary retention due to additive anticholinergic effects from both drugs."
"Pargyline, a monoamine oxidase inhibitor (MAOI), irreversibly inhibits the metabolism of amines, leading to increased intraneuronal stores of norepinephrine. Hydrocodone, a semisynthetic opioid, can release these stored catecholamines, potentially causing a hypertensive crisis, serotonin syndrome, or CNS excitation. Coadministration may also result in excessive sedation and respiratory depression due to additive CNS depressant effects, requiring immediate clinical attention."
"Hydrocodone, an opioid agonist, and oxprenolol, a non-selective beta-adrenoceptor antagonist, are both central nervous system (CNS) depressants. Their combined use can lead to additive CNS depression, resulting in excessive sedation, respiratory depression, hypotension, and bradycardia. This interaction is particularly dangerous in patients with compromised cardiac or respiratory function, potentially leading to coma or death."
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about AMBENYL vs ACETAMINOPHEN AND HYDROCODONE BITARTRATE, answered by our medical review team.
AMBENYL is a Antitussive/Antihistamine Combination that works by AMBENYL is a combination product containing codeine (opioid agonist) and bromodiphenhydramine (antihistamine). Codeine binds to mu-opioid receptors in the CNS, inhibiting ascending pain pathways and altering pain perception; bromodiphenhydramine antagonizes histamine H1 receptors, producing antitussive and sedative effects.. ACETAMINOPHEN AND HYDROCODONE BITARTRATE is a Opioid Agonist that works by Acetaminophen: analgesic and antipyretic effects via inhibition of cyclooxygenase (COX) and activation of descending serotonergic pathways; central action. Hydrocodone: mu-opioid receptor agonist; activates G-protein coupled receptors to modulate pain perception and emotional response.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between AMBENYL and ACETAMINOPHEN AND HYDROCODONE BITARTRATE depend on the specific clinical indication. These are agents from distinct pharmacological classes and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of AMBENYL is: Each 5 m L contains codeine phosphate 10 mg and diphenhydramine hydrochloride 12.5 mg. Adults: 10 m L (2 teaspoonfuls) orally every 4-6 hours as needed; maximum 40 m L per day.. The standard adult dose of ACETAMINOPHEN AND HYDROCODONE BITARTRATE is: 1-2 tablets (containing 5-10 mg hydrocodone and 300-325 mg acetaminophen) orally every 4-6 hours as needed for pain; maximum 8 tablets per day.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between AMBENYL and ACETAMINOPHEN AND HYDROCODONE BITARTRATE in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. AMBENYL is classified as Category C. FDA Pregnancy Category C. First trimester: Limited data; potential for fetal malformations (cleft palate, cardiac defects) based on animal studies with high-dose antihistamines. Se. ACETAMINOPHEN AND HYDROCODONE BITARTRATE is classified as Category D/X. First trimester: Acetaminophen considered low risk; hydrocodone is a pregnancy category C drug. Data from retrospective studies suggest a small increased risk of certain congenital. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.