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Acetaminophen and methocarbamol (United States: Not available): Drug information

Acetaminophen and methocarbamol (United States: Not available): Drug information
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For additional information see "Acetaminophen and methocarbamol (United States: Not available): Patient drug information"

For abbreviations, symbols, and age group definitions show table
Brand Names: Canada
  • Muscle & Back Pain Relief [OTC];
  • Robaxacet [OTC]
Pharmacologic Category
  • Skeletal Muscle Relaxant
Dosing: Adult

Note: Use lowest effective dose.

Muscle pain

Muscle pain: Oral: Acetaminophen 325 to 500 mg/methocarbamol 400 mg per tablet: Two tablets every 6 hours (maximum: 8 tablets/day).

Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.

Dosing: Kidney Impairment: Adult

There are no dosage adjustments provided in the manufacturer's labeling; use caution in severe impairment. Also see individual agents.

Dosing: Liver Impairment: Adult

There are no dosage adjustments provided in the manufacturer's labeling; use caution. Also see individual agents.

Dosing: Older Adult

Avoid use (Ref).

Dosing: Pediatric
Muscle pain

Muscle pain: Children ≥12 years and Adolescents: Oral: Refer to adult dosing.

Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.

Dosing: Kidney Impairment: Pediatric

There are no dosage adjustments provided in the manufacturer's labeling; use caution. See individual agents.

Dosing: Liver Impairment: Pediatric

There are no dosage adjustments provided in the manufacturer's labeling; use caution. See individual agents.

Adverse Reactions

See individual agents.

Contraindications

OTC labeling: When used for self-medication, do not use with other drug products containing acetaminophen or methocarbamol; do not use with a monamine oxidase inhibitor (MAOI) or for two weeks after stopping an MAOI.

Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.

Warnings/Precautions

Concerns related to adverse effects:

• CNS depression: May cause CNS depression, which may impair physical or mental abilities; patients must be cautioned about performing tasks which require mental alertness (eg, operating machinery or driving).

• Hepatotoxicity: Hepatotoxicity (including serious and potentially fatal toxicity) may occur and is usually associated with excessive acetaminophen intake (often involves more than one acetaminophen-containing product) and/or consumption of 3 or more alcoholic drinks/day. Do not exceed the maximum recommended daily dose (>4 g daily in adults). In addition, chronic daily dosing may also result in liver damage in some patients.

• Hypersensitivity/anaphylactic reactions: Hypersensitivity and anaphylactic reactions have been reported with acetaminophen; discontinue immediately if symptoms of allergic or hypersensitivity reactions occur.

• Skin reactions: Serious and potentially fatal skin reactions, including acute generalized exanthematous pustulosis (AGEP), Stevens-Johnson syndrome (SJS), and toxic epidermal necrolysis (TEN) have occurred rarely with acetaminophen use. Discontinue therapy at the first appearance of skin rash (FDA 2013).

Disease-related concerns:

• Ethanol use: Use with caution in patients with alcoholic liver disease; consuming ≥3 alcoholic drinks/day may increase the risk of liver damage.

• Hepatic impairment: Use with caution in patients with hepatic impairment or active liver disease.

• Renal impairment: Use with caution in patients with severe renal impairment.

• Seizure disorder: Use with caution in patients with a history of seizure disorder; seizures have been reported with methocarbamol (Methocarbamol US product labeling 2018).

Other warnings/precautions:

• Dosage limit: Limit acetaminophen dose from all sources (prescription, OTC, combination products) and all routes of administration (IV, oral, rectal) to <4 g/day (adults).

• Self-medication (OTC use): When used for self-medication, patients should stop use and contact health care provider if pain lasts longer than 5 days.

Product Availability

Not available in the US

Dosage Forms: Canada

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Tablet, Oral:

Muscle & Back Pain Relief: Acetaminophen 500 mg and methocarbamol 400 mg

Robaxacet: Acetaminophen 325 mg and methocarbamol 400 mg

Use: Labeled Indications

Note: Not approved in the US

Muscle pain: Relief of pain associated with muscle spasms including back pain, tense neck muscles, strains and sprains in adults and pediatric patients 12 years and older

Medication Safety Issues
Sound-alike/look-alike issues:

Robaxacet may be confused with Percocet, Robaxin

Older Adult: High-Risk Medication:

Beers Criteria: Methocarbamol is identified in the Beers Criteria as a potentially inappropriate medication to be avoided in patients 65 years and older (independent of diagnosis or condition) because most muscle relaxants are poorly tolerated in older adults due to anticholinergic effects caused by some muscle relaxants, risk of sedation, and an increased risk of fracture. In addition, efficacy is questionable at doses tolerated by geriatric patients (Beers Criteria [AGS 2023]).

Other safety concerns:

Duplicate therapy issues: This product contains acetaminophen, which may be a component of combination products. Do not exceed the maximum recommended daily dose of acetaminophen.

Metabolism/Transport Effects

Refer to individual components.

Drug Interactions

Note: Interacting drugs may not be individually listed below if they are part of a group interaction (eg, individual drugs within “CYP3A4 Inducers [Strong]” are NOT listed). For a complete list of drug interactions by individual drug name and detailed management recommendations, use the drug interactions program by clicking on the “Launch drug interactions program” link above.

Acrivastine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Alcohol (Ethyl): May increase hepatotoxic effects of Acetaminophen. Risk C: Monitor

Alizapride: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Amisulpride (Oral): May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Articaine: May increase CNS depressant effects of CNS Depressants. Management: Consider reducing the dose of articaine if possible when used in patients who are also receiving CNS depressants. Monitor for excessive CNS depressant effects with any combined use. Risk D: Consider Therapy Modification

Atazanavir: May increase serum concentration of UGT1A1 Substrates. Management: Do not use UGT1A1 substrates for which small increases in exposure can cause serious adverse effects together with atazanavir, and use caution with any UGT1A1 substrate, even when small changes in exposure are less likely to cause serious adverse effects. Risk D: Consider Therapy Modification

Azelastine (Nasal): May increase CNS depressant effects of CNS Depressants. Risk X: Avoid

Belumosudil: May increase serum concentration of UGT1A1 Substrates. Management: Avoid coadministration of belumosudil with substrates of UGT1A1 for which minimal concentration increases can cause serious adverse effects. If coadministration is required, dose reductions of the UGT1A1 substrate may be required. Risk D: Consider Therapy Modification

Benperidol: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Blonanserin: CNS Depressants may increase CNS depressant effects of Blonanserin. Management: Use caution if coadministering blonanserin and CNS depressants; dose reduction of the other CNS depressant may be required. Strong CNS depressants should not be coadministered with blonanserin. Risk D: Consider Therapy Modification

Botulinum Toxin-Containing Products: Muscle Relaxants (Centrally Acting) may increase adverse/toxic effects of Botulinum Toxin-Containing Products. Specifically, the risk for increased muscle weakness may be enhanced. Risk C: Monitor

Brexanolone: CNS Depressants may increase CNS depressant effects of Brexanolone. Risk C: Monitor

Brimonidine (Topical): May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Bromopride: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Bromperidol: May increase CNS depressant effects of CNS Depressants. Risk X: Avoid

Buclizine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Buprenorphine: CNS Depressants may increase CNS depressant effects of Buprenorphine. Management: Consider reduced doses of other CNS depressants, and avoiding such drugs in patients at high risk of buprenorphine overuse/self-injection. Initiate buprenorphine at lower doses in patients already receiving CNS depressants. Risk D: Consider Therapy Modification

BusPIRone: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Busulfan: Acetaminophen may increase serum concentration of Busulfan. Risk C: Monitor

Cannabinoid-Containing Products: CNS Depressants may increase CNS depressant effects of Cannabinoid-Containing Products. Risk C: Monitor

CarBAMazepine: May increase metabolism of Acetaminophen. This may 1) diminish the effect of acetaminophen; and 2) increase the risk of liver damage. Risk C: Monitor

Cetirizine (Systemic): May increase CNS depressant effects of CNS Depressants. Management: Consider avoiding this combination if possible. If required, monitor for excessive sedation or CNS depression, limit the dose and duration of combination therapy, and consider CNS depressant dose reductions. Risk D: Consider Therapy Modification

Chloral Hydrate/Chloral Betaine: CNS Depressants may increase CNS depressant effects of Chloral Hydrate/Chloral Betaine. Management: Consider alternatives to the use of chloral hydrate or chloral betaine and additional CNS depressants. If combined, consider a dose reduction of either agent and monitor closely for enhanced CNS depressive effects. Risk D: Consider Therapy Modification

Chlormethiazole: May increase CNS depressant effects of CNS Depressants. Management: Monitor closely for evidence of excessive CNS depression. The chlormethiazole labeling states that an appropriately reduced dose should be used if such a combination must be used. Risk D: Consider Therapy Modification

Chlorphenesin Carbamate: May increase adverse/toxic effects of CNS Depressants. Risk C: Monitor

CNS Depressants: May increase adverse/toxic effects of CNS Depressants. Risk C: Monitor

Dantrolene: May increase adverse neuromuscular effects of Muscle Relaxants (Centrally Acting). Specifically, neuromuscular block may be potentiated. Risk C: Monitor

Dapsone (Topical): May increase adverse/toxic effects of Methemoglobinemia Associated Agents. Risk C: Monitor

Daridorexant: May increase CNS depressant effects of CNS Depressants. Management: Dose reduction of daridorexant and/or any other CNS depressant may be necessary. Use of daridorexant with alcohol is not recommended, and the use of daridorexant with any other drug to treat insomnia is not recommended. Risk D: Consider Therapy Modification

Dasatinib: Acetaminophen may increase hepatotoxic effects of Dasatinib. Dasatinib may increase serum concentration of Acetaminophen. Management: Avoid coadministration of acetaminophen and dasatinib if possible. If coadministration is unavoidable, monitor for signs/symptoms of hepatotoxicity, particularly in patients with greater acetaminophen exposure. Risk D: Consider Therapy Modification

DexmedeTOMIDine: CNS Depressants may increase CNS depressant effects of DexmedeTOMIDine. Management: Monitor for increased CNS depression during coadministration of dexmedetomidine and CNS depressants, and consider dose reductions of either agent to avoid excessive CNS depression. Risk D: Consider Therapy Modification

Difelikefalin: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Difenoxin: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Dihydralazine: CNS Depressants may increase hypotensive effects of Dihydralazine. Risk C: Monitor

Dimethindene (Topical): May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Dothiepin: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Doxylamine: CNS Depressants may increase CNS depressant effects of Doxylamine. Risk C: Monitor

DroPERidol: May increase CNS depressant effects of CNS Depressants. Management: Consider dose reductions of droperidol or of other CNS agents (eg, opioids, barbiturates) with concomitant use. Risk D: Consider Therapy Modification

Emedastine (Systemic): May increase CNS depressant effects of CNS Depressants. Management: Consider avoiding this combination if possible. If required, monitor for excessive sedation or CNS depression, limit the dose and duration of combination therapy, and consider CNS depressant dose reductions. Risk C: Monitor

Entacapone: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Eperisone: May increase adverse/toxic effects of Methocarbamol. Specifically the risk for visual disturbances and enhanced CNS depressant effects may be increased. Risk C: Monitor

Esketamine (Nasal): May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Flucloxacillin: May increase adverse/toxic effects of Acetaminophen. Specifically, the risk for high anion gap metabolic acidosis may be increased. Risk C: Monitor

Flunarizine: CNS Depressants may increase CNS depressant effects of Flunarizine. Risk X: Avoid

Flunitrazepam: CNS Depressants may increase CNS depressant effects of Flunitrazepam. Management: Reduce the dose of CNS depressants when combined with flunitrazepam and monitor patients for evidence of CNS depression (eg, sedation, respiratory depression). Use non-CNS depressant alternatives when available. Risk D: Consider Therapy Modification

Fosphenytoin-Phenytoin: May decrease serum concentration of Acetaminophen. Specifically, serum concentrations of acetaminophen may be decreased (leading to decreased efficacy), but the formation of the toxic N-acetyl-p-benzoquinone imine (NAPQI) metabolite may be increased (leading to increased hepatotoxicity). Risk C: Monitor

HydrOXYzine: May increase CNS depressant effects of CNS Depressants. Management: Consider a decrease in the CNS depressant dose, as appropriate, when used together with hydroxyzine. Increase monitoring of signs/symptoms of CNS depression in any patient receiving hydroxyzine together with another CNS depressant. Risk D: Consider Therapy Modification

Imatinib: Acetaminophen may increase hepatotoxic effects of Imatinib. Risk C: Monitor

Immune Checkpoint Inhibitors (Anti-PD-1, -PD-L1, and -CTLA4 Therapies): Acetaminophen may decrease therapeutic effects of Immune Checkpoint Inhibitors (Anti-PD-1, -PD-L1, and -CTLA4 Therapies). Risk C: Monitor

Isoniazid: May increase hepatotoxic effects of Acetaminophen. Isoniazid may increase metabolism of Acetaminophen. Specifically, formation of the hepatotoxic NAPQI metabolite may be increased. Risk C: Monitor

Ixabepilone: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Kava Kava: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Ketotifen (Systemic): May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Kratom: May increase CNS depressant effects of CNS Depressants. Risk X: Avoid

LamoTRIgine: Acetaminophen may decrease serum concentration of LamoTRIgine. Risk C: Monitor

Lemborexant: May increase CNS depressant effects of CNS Depressants. Management: Dosage adjustments of lemborexant and of concomitant CNS depressants may be necessary when administered together because of potentially additive CNS depressant effects. Close monitoring for CNS depressant effects is necessary. Risk D: Consider Therapy Modification

Levocetirizine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Lisuride: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Local Anesthetics: Methemoglobinemia Associated Agents may increase adverse/toxic effects of Local Anesthetics. Specifically, the risk for methemoglobinemia may be increased. Risk C: Monitor

Lofepramine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Lofexidine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Lorlatinib: May decrease serum concentration of Acetaminophen. Risk C: Monitor

Loxapine: CNS Depressants may increase CNS depressant effects of Loxapine. Management: Consider reducing the dose of CNS depressants administered concomitantly with loxapine due to an increased risk of respiratory depression, sedation, hypotension, and syncope. Risk D: Consider Therapy Modification

Magnesium Sulfate: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Melitracen [INT]: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Mequitazine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Metergoline: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Methotrimeprazine: CNS Depressants may increase CNS depressant effects of Methotrimeprazine. Methotrimeprazine may increase CNS depressant effects of CNS Depressants. Management: Reduce the usual dose of CNS depressants by 50% if starting methotrimeprazine until the dose of methotrimeprazine is stable. Monitor patient closely for evidence of CNS depression. Risk D: Consider Therapy Modification

Methoxyflurane: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Metoclopramide: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

MetyraPONE: May increase serum concentration of Acetaminophen. More importantly, by inhibiting the conjugative metabolism of acetaminophen, metyrapone may shift the metabolism towards the oxidative route that produces a hepatotoxic metabolite. Risk X: Avoid

MetyroSINE: CNS Depressants may increase sedative effects of MetyroSINE. Risk C: Monitor

Minocycline (Systemic): May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Mitapivat: May decrease serum concentration of UGT1A1 Substrates. Risk C: Monitor

Moxonidine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Nabilone: May increase CNS depressant effects of CNS Depressants. Risk X: Avoid

Nalfurafine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Nitric Oxide: May increase adverse/toxic effects of Methemoglobinemia Associated Agents. Combinations of these agents may increase the likelihood of significant methemoglobinemia. Risk C: Monitor

Noscapine: CNS Depressants may increase adverse/toxic effects of Noscapine. Risk X: Avoid

Olopatadine (Nasal): May increase CNS depressant effects of CNS Depressants. Risk X: Avoid

Opicapone: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Opioid Agonists: CNS Depressants may increase CNS depressant effects of Opioid Agonists. Management: Avoid concomitant use of opioid agonists and benzodiazepines or other CNS depressants when possible. These agents should only be combined if alternative treatment options are inadequate. If combined, limit the dosages and duration of each drug. Risk D: Consider Therapy Modification

Opipramol: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Orphenadrine: CNS Depressants may increase CNS depressant effects of Orphenadrine. Risk X: Avoid

Oxomemazine: May increase CNS depressant effects of CNS Depressants. Risk X: Avoid

Oxybate Salt Products: CNS Depressants may increase CNS depressant effects of Oxybate Salt Products. Management: Consider alternatives to this combination when possible. If combined, dose reduction or discontinuation of one or more CNS depressants (including the oxybate salt product) should be considered. Interrupt oxybate salt treatment during short-term opioid use Risk D: Consider Therapy Modification

OxyCODONE: CNS Depressants may increase CNS depressant effects of OxyCODONE. Management: Avoid concomitant use of oxycodone and benzodiazepines or other CNS depressants when possible. These agents should only be combined if alternative treatment options are inadequate. If combined, limit the dosages and duration of each drug. Risk D: Consider Therapy Modification

Paliperidone: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Paraldehyde: CNS Depressants may increase CNS depressant effects of Paraldehyde. Risk X: Avoid

Perampanel: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Periciazine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

PHENobarbital: May increase metabolism of Acetaminophen. Specifically, formation of the hepatotoxic NAPQI metabolite may be increased. Risk C: Monitor

Phenylephrine (Systemic): Acetaminophen may increase serum concentration of Phenylephrine (Systemic). Risk C: Monitor

Pipamperone: May increase adverse/toxic effects of CNS Depressants. Risk C: Monitor

Piribedil: CNS Depressants may increase CNS depressant effects of Piribedil. Risk C: Monitor

Pizotifen: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Pramipexole: CNS Depressants may increase sedative effects of Pramipexole. Risk C: Monitor

Prilocaine: Methemoglobinemia Associated Agents may increase adverse/toxic effects of Prilocaine. Combinations of these agents may increase the likelihood of significant methemoglobinemia. Management: Monitor for signs of methemoglobinemia when prilocaine is used in combination with other agents associated with development of methemoglobinemia. Avoid use of these agents with prilocaine/lidocaine cream in infants less than 12 months of age. Risk C: Monitor

Primaquine: Methemoglobinemia Associated Agents may increase adverse/toxic effects of Primaquine. Specifically, the risk for methemoglobinemia may be increased. Management: Avoid concomitant use of primaquine and other drugs that are associated with methemoglobinemia when possible. If combined, monitor methemoglobin levels closely. Risk D: Consider Therapy Modification

Primidone: May increase metabolism of Acetaminophen. Specifically, formation of the hepatotoxic NAPQI metabolite may be increased. Risk C: Monitor

Probenecid: May increase serum concentration of Acetaminophen. Probenecid may also limit the formation of at least one major non-toxic metabolite, possibly increasing the potential for formation of the toxic NAPQI metabolite. Management: Consider limiting acetaminophen use in combination with probenecid. Probenecid may reduce clearance of acetaminophen to one of its non-toxic metabolities, increasing the risk for acetaminophen toxicity, even a lower doses. Risk D: Consider Therapy Modification

Procarbazine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

RifAMPin: May increase hepatotoxic effects of Acetaminophen. RifAMPin may decrease serum concentration of Acetaminophen. Risk C: Monitor

Rilmenidine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Ropeginterferon Alfa-2b: CNS Depressants may increase adverse/toxic effects of Ropeginterferon Alfa-2b. Specifically, the risk of neuropsychiatric adverse effects may be increased. Management: Avoid coadministration of ropeginterferon alfa-2b and other CNS depressants. If this combination cannot be avoided, monitor patients for neuropsychiatric adverse effects (eg, depression, suicidal ideation, aggression, mania). Risk D: Consider Therapy Modification

ROPINIRole: CNS Depressants may increase sedative effects of ROPINIRole. Risk C: Monitor

Rotigotine: CNS Depressants may increase sedative effects of Rotigotine. Risk C: Monitor

Sodium Nitrite: Methemoglobinemia Associated Agents may increase adverse/toxic effects of Sodium Nitrite. Combinations of these agents may increase the likelihood of significant methemoglobinemia. Risk C: Monitor

SORAfenib: Acetaminophen may increase hepatotoxic effects of SORAfenib. SORAfenib may increase serum concentration of Acetaminophen. Management: Avoid coadministration of acetaminophen and sorafenib if possible. If coadministration is unavoidable, monitor for signs/symptoms of hepatotoxicity, particularly in patients with greater acetaminophen exposure. Risk D: Consider Therapy Modification

Suvorexant: CNS Depressants may increase CNS depressant effects of Suvorexant. Management: Dose reduction of suvorexant and/or any other CNS depressant may be necessary. Use of suvorexant with alcohol is not recommended, and the use of suvorexant with any other drug to treat insomnia is not recommended. Risk D: Consider Therapy Modification

Thalidomide: CNS Depressants may increase CNS depressant effects of Thalidomide. Risk X: Avoid

Tolperisone: May increase adverse/toxic effects of Muscle Relaxants (Centrally Acting). Management: Monitor for increased sedation or CNS effects if tolperisone is combined with other centrally acting muscle relaxants. Consider decreasing the tolperisone dose if these agents are combined. Risk D: Consider Therapy Modification

Trimeprazine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Vaccines: Acetaminophen may decrease therapeutic effects of Vaccines. Management: Consider avoiding routine prophylactic use of acetaminophen before or during vaccine administration when possible. Acetaminophen is still recommended to treat fevers and/or pain that occurs after vaccination. Risk D: Consider Therapy Modification

Valerian: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Vitamin K Antagonists: Acetaminophen may increase anticoagulant effects of Vitamin K Antagonists. This appears most likely with daily acetaminophen doses exceeding 1.3 or 2 g/day for multiple consecutive days. Risk C: Monitor

Zolpidem: CNS Depressants may increase CNS depressant effects of Zolpidem. Management: Reduce the Intermezzo brand sublingual zolpidem adult dose to 1.75 mg for men who are also receiving other CNS depressants. No such dose change is recommended for women. Avoid use with other CNS depressants at bedtime; avoid use with alcohol. Risk D: Consider Therapy Modification

Zuranolone: May increase CNS depressant effects of CNS Depressants. Management: Consider alternatives to the use of zuranolone with other CNS depressants or alcohol. If combined, consider a zuranolone dose reduction and monitor patients closely for increased CNS depressant effects. Risk D: Consider Therapy Modification

Pregnancy Considerations

Refer to individual monographs.

Breastfeeding Considerations

Refer to individual monographs.

Monitoring Parameters

Pain relief

Mechanism of Action

Acetaminophen: Although not fully elucidated, the analgesic effects are believed to be due to activation of descending serotonergic inhibitory pathways in the CNS. Interactions with other nociceptive systems may be involved as well (Smith 2009).

Methocarbamol: Causes skeletal muscle relaxation by general CNS depression.

Pharmacokinetics (Adult Data Unless Noted)

Refer to individual agents.

Pharmacokinetics: Additional Considerations (Adult Data Unless Noted)

Refer to individual agents.

Brand Names: International
International Brand Names by Country
For country code abbreviations (show table)

  • (AE) United Arab Emirates: Distem;
  • (CI) Côte d'Ivoire: Distem;
  • (CO) Colombia: Bioflex | Hital | Hitalke | Jaquedol | Metacet | Relaxal | Robaxifen | Sinaxar a | Wintroplex;
  • (DO) Dominican Republic: Distem | Laxifen | Metofen | Wintroplex;
  • (EC) Ecuador: Wintroplex;
  • (EG) Egypt: Flexpro extra;
  • (ES) Spain: Distem;
  • (HU) Hungary: Midexon;
  • (IN) India: Flexinol | Robinaxol | Ultranac mr;
  • (KR) Korea, Republic of: Amer | Analexen | Cobaxin | Mechareuphen | Menofen | Metalex | Metareo | Metba | Methosin | Metopen | Metva | Micamol | Pharmiphen | Pharmiphen plus;
  • (LB) Lebanon: Distem | Flexpro extra;
  • (MX) Mexico: Carbafen | Robaxifen;
  • (PE) Peru: Mioenddol;
  • (PK) Pakistan: Baxamin;
  • (TR) Turkey: Miyorel;
  • (UG) Uganda: Distem;
  • (VE) Venezuela, Bolivarian Republic of: Robaxifen;
  • (VN) Viet Nam: Clopidmeyer | Savimetoc
  1. 2023 American Geriatrics Society Beers Criteria Update Expert Panel. American Geriatrics Society 2023 updated AGS Beers Criteria for potentially inappropriate medication use in older adults. J Am Geriatr Soc. 2023;71(7):2052-2081. doi:10.1111/jgs.18372 [PubMed 37139824]
  2. FDA Drug Safety Communication: FDA warns of rare but serious skin reactions with the pain reliever/fever reducer acetaminophen. Food and Drug Administration website. https://www.fda.gov/Drugs/DrugSafety/ucm363041.htm. Accessed 7/9/2018.
  3. Robaxacet (acetaminophen and methocarbamol) [product monograph]. Mississauga, Ontario, Canada: Pfizer Canada; November 2014.
  4. Robaxacet ES (acetaminophen and methocarbamol) [product monograph]. Mississauga, Ontario, Canada: Pfizer Canada; November 2014.
  5. Smith HS. Potential analgesic mechanisms of acetaminophen. Pain Physician. 2009;12:269-280. [PubMed 19165309]
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