Pentazocine and Acetaminophen

Use this medicine as ordered by your doctor. Read all information given to you. Follow all instructions closely.

• Take with or without food. Take with food if it causes an upset stomach.

What do I do if I miss a dose?

• If you take pentazocine and acetaminophen on a regular basis, take a missed dose as soon as you think about it.
• If it is close to the time for your next dose, skip the missed dose and go back to your normal time.
• Do not take 2 doses at the same time or extra doses.
• Many times this medicine is taken on an as needed basis. Do not take more often than told by the doctor.

If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

Analgesic: Oral: Children ≥12 years: Refer to adult dosing.

Alvimopan: Analgesics (Opioid) may enhance the adverse/toxic effect of Alvimopan. This is most notable for patients receiving long-term (i.e., more than 7 days) opiates prior to alvimopan initiation. Management: Alvimopan is contraindicated in patients receiving therapeutic doses of opioids for more than 7 consecutive days immediately prior to alvimopan initiation. Consider therapy modification

Amphetamines: May enhance the analgesic effect of Analgesics (Opioid). Monitor therapy

Analgesics (Opioid): Mixed Agonist / Antagonist Opioids may diminish the analgesic effect of Analgesics (Opioid). Management: Seek alternatives to mixed agonist/antagonist opioids in patients receiving pure opioid agonists, and monitor for symptoms of therapeutic failure/high dose requirements (or withdrawal in opioid-dependent patients) if patients receive these combinations. Exceptions: Buprenorphine; Butorphanol; Meptazinol; Nalbuphine; Pentazocine. Avoid combination

Anticholinergic Agents: May enhance the adverse/toxic effect of Analgesics (Opioid). Specifically, the risk for constipation and urinary retention may be increased with this combination. Monitor therapy

Azelastine (Nasal): CNS Depressants may enhance the CNS depressant effect of Azelastine (Nasal). Avoid combination

Blonanserin: CNS Depressants may enhance the CNS depressant effect of Blonanserin. Consider therapy modification

Brimonidine (Topical): May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Buprenorphine: Mixed Agonist / Antagonist Opioids may diminish the therapeutic effect of Buprenorphine. This combination may also induce opioid withdrawal. Avoid combination

Busulfan: Acetaminophen may increase the serum concentration of Busulfan. Monitor therapy

Cannabis: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Chlormethiazole: May enhance the CNS depressant effect 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. Consider therapy modification

Chlorphenesin Carbamate: May enhance the adverse/toxic effect of CNS Depressants. Monitor therapy

Cholestyramine Resin: May decrease the absorption of Acetaminophen. Effect is minimal if cholestyramine is administered 1 hour after acetaminophen. Consider therapy modification

CNS Depressants: May enhance the CNS depressant effect of Analgesics (Opioid). Management: Avoid concomitant use of opioid analgesics 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. Consider therapy modification

Dapsone (Topical): May enhance the adverse/toxic effect of Methemoglobinemia Associated Agents. Monitor therapy

Dasatinib: Acetaminophen may enhance the hepatotoxic effect of Dasatinib. Dasatinib may increase the serum concentration of Acetaminophen. Consider therapy modification

Desmopressin: Analgesics (Opioid) may enhance the adverse/toxic effect of Desmopressin. Monitor therapy

Dimethindene (Topical): May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Diuretics: Analgesics (Opioid) may enhance the adverse/toxic effect of Diuretics. Analgesics (Opioid) may diminish the therapeutic effect of Diuretics. Monitor therapy

Dronabinol: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Droperidol: May enhance the CNS depressant effect of CNS Depressants. Management: Consider dose reductions of droperidol or of other CNS agents (e.g., opioids, barbiturates) with concomitant use. Consider therapy modification

Eluxadoline: Analgesics (Opioid) may enhance the constipating effect of Eluxadoline. Avoid combination

Flunitrazepam: CNS Depressants may enhance the CNS depressant effect of Flunitrazepam. Consider therapy modification

Gastrointestinal Agents (Prokinetic): Analgesics (Opioid) may diminish the therapeutic effect of Gastrointestinal Agents (Prokinetic). Monitor therapy

Imatinib: Acetaminophen may enhance the hepatotoxic effect of Imatinib. Monitor therapy

Isoniazid: May enhance the adverse/toxic effect of Acetaminophen. Monitor therapy

Kava Kava: May enhance the adverse/toxic effect of CNS Depressants. Monitor therapy

Lofexidine: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Magnesium Sulfate: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Methotrimeprazine: May enhance the CNS depressant effect of CNS Depressants. CNS Depressants may enhance the CNS depressant effect of Methotrimeprazine. Management: Reduce adult dose of CNS depressant agents by 50% with initiation of concomitant methotrimeprazine therapy. Further CNS depressant dosage adjustments should be initiated only after clinically effective methotrimeprazine dose is established. Consider therapy modification

MetyraPONE: May increase the 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. Monitor therapy

MetyroSINE: CNS Depressants may enhance the sedative effect of MetyroSINE. Monitor therapy

Minocycline: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Mipomersen: Acetaminophen may enhance the hepatotoxic effect of Mipomersen. Monitor therapy

Nabilone: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Nalmefene: May diminish the therapeutic effect of Analgesics (Opioid). Management: Avoid the concomitant use of nalmefene and opioid analgesics. Discontinue nalmefene 1 week prior to any anticipated use of opioid analgesics. If combined, larger doses of opioid analgesics will likely be required. Consider therapy modification

Naltrexone: May diminish the therapeutic effect of Analgesics (Opioid). Management: Seek therapeutic alternatives to opioids. See full drug interaction monograph for detailed recommendations. Consider therapy modification

Nitric Oxide: May enhance the adverse/toxic effect of Methemoglobinemia Associated Agents. Combinations of these agents may increase the likelihood of significant methemoglobinemia. Management: Monitor patients for signs of methemoglobinemia (e.g., hypoxia, cyanosis) when nitric oxide is used in combination with other agents associated with development of methemoglobinemia. Avoid lidocaine/prilocaine. Monitor therapy

Orphenadrine: CNS Depressants may enhance the CNS depressant effect of Orphenadrine. Avoid combination

Oxomemazine: May enhance the CNS depressant effect of CNS Depressants. Avoid combination

Paraldehyde: CNS Depressants may enhance the CNS depressant effect of Paraldehyde. Avoid combination

Pegvisomant: Analgesics (Opioid) may diminish the therapeutic effect of Pegvisomant. Monitor therapy

Perampanel: May enhance the CNS depressant effect of CNS Depressants. Management: Patients taking perampanel with any other drug that has CNS depressant activities should avoid complex and high-risk activities, particularly those such as driving that require alertness and coordination, until they have experience using the combination. Consider therapy modification

Phenylephrine (Systemic): Acetaminophen may increase the serum concentration of Phenylephrine (Systemic). Monitor therapy

Piribedil: CNS Depressants may enhance the CNS depressant effect of Piribedil. Monitor therapy

Pramipexole: CNS Depressants may enhance the sedative effect of Pramipexole. Monitor therapy

Prilocaine: Methemoglobinemia Associated Agents may enhance the adverse/toxic effect of Prilocaine. Combinations of these agents may increase the likelihood of significant methemoglobinemia. Management: Monitor patients for signs of methemoglobinemia (e.g., hypoxia, cyanosis) when prilocaine is used in combination with other agents associated with development of methemoglobinemia. Avoid lidocaine/prilocaine in infants receiving such agents. Monitor therapy

Probenecid: May increase the 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. Consider therapy modification

Ramosetron: Analgesics (Opioid) may enhance the constipating effect of Ramosetron. Monitor therapy

ROPINIRole: CNS Depressants may enhance the sedative effect of ROPINIRole. Monitor therapy

Rotigotine: CNS Depressants may enhance the sedative effect of Rotigotine. Monitor therapy

Rufinamide: May enhance the adverse/toxic effect of CNS Depressants. Specifically, sleepiness and dizziness may be enhanced. Monitor therapy

Selective Serotonin Reuptake Inhibitors: CNS Depressants may enhance the adverse/toxic effect of Selective Serotonin Reuptake Inhibitors. Specifically, the risk of psychomotor impairment may be enhanced. Monitor therapy

Serotonin Modulators: Analgesics (Opioid) may enhance the serotonergic effect of Serotonin Modulators. This could result in serotonin syndrome. Exceptions: Nicergoline. Monitor therapy

Sodium Nitrite: Methemoglobinemia Associated Agents may enhance the adverse/toxic effect of Sodium Nitrite. Combinations of these agents may increase the likelihood of significant methemoglobinemia. Monitor therapy

Sodium Oxybate: May enhance the CNS depressant effect of CNS Depressants. Management: Consider alternatives to combined use. When combined use is needed, consider minimizing doses of one or more drugs. Use of sodium oxybate with alcohol or sedative hypnotics is contraindicated. Consider therapy modification

SORAfenib: Acetaminophen may enhance the hepatotoxic effect of SORAfenib. SORAfenib may increase the serum concentration of Acetaminophen. Consider therapy modification

Succinylcholine: May enhance the bradycardic effect of Analgesics (Opioid). Monitor therapy

Suvorexant: CNS Depressants may enhance the CNS depressant effect 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. Consider therapy modification

Tetracaine (Topical): May enhance the adverse/toxic effect of Methemoglobinemia Associated Agents. Monitor therapy

Tetrahydrocannabinol: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Thalidomide: CNS Depressants may enhance the CNS depressant effect of Thalidomide. Avoid combination

Vitamin K Antagonists (eg, warfarin): Acetaminophen may enhance the anticoagulant effect of Vitamin K Antagonists. This appears most likely with daily acetaminophen doses exceeding 1.3 or 2 g/day for multiple consecutive days. Monitor therapy

Zolpidem: CNS Depressants may enhance the CNS depressant effect 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. Consider therapy modification

Concerns related to adverse effects:

• Adrenal insufficiency: Use with caution in patients with adrenal insufficiency, including Addison's disease. Long-term opioid use may cause secondary hypogonadism, which may lead to sexual dysfunction, infertility, mood disorders, and osteoporosis (Brennan, 2013).

• CNS effects: 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). Confusion, disorientation, and visual hallucinations have occurred in some patients, but usually clears within a few hours; observe patients closely.

• Hepatotoxicity: [US Boxed Warning]: Acetaminophen may cause severe hepatotoxicity, potentially requiring liver transplant or resulting in death; hepatotoxicity is usually associated with excessive acetaminophen intake (>4 g/day). Risk is increased with alcohol use, pre-existing liver disease, and intake of more than one source of acetaminophen-containing medications. Chronic daily dosing in adults has also resulted in liver damage in some patients.

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

• Skin reactions: Rarely, acetaminophen may cause serious and potentially fatal skin reactions such as acute generalized exanthematous pustulosis, Stevens-Johnson syndrome (SJS), and toxic epidermal necrolysis (TEN). Discontinue treatment if severe skin reactions develop.

Disease-related concerns:

• Abdominal conditions: May obscure diagnosis or clinical course of patients with acute abdominal conditions.

• Adrenal insufficiency: Use with caution in patients with adrenal insufficiency, including Addison disease.

• Biliary tract impairment: Use pentazocine with caution in patients with biliary tract dysfunction, including acute pancreatitis; may cause constriction of sphincter of Oddi.

• Bowel disease: Use with caution in patients with inflammatory or obstructive bowel disease.

• CNS depression/coma: Avoid use in patients with CNS depression or coma as these patients are susceptible to intracranial effects of CO2 retention.

• Drug abuse: Use opioids for chronic pain with caution in patients at increased risk for misuse; factors associated with increased risk include previous substance use disorder, younger age, concomitant depression (major), and psychotropic medication use. Consider offering naloxone prescriptions in patients with factors associated with an increased risk for overdose, such as history of overdose or substance use disorder, higher opioid dosages (≥50 morphine milligram equivalents/day orally), and concomitant benzodiazepine use (Dowell [CDC 2016]).

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

• G6PD deficiency: Use with caution in patients with known G6PD deficiency.

• Head trauma: Use with extreme caution in patients with head injury, intracranial lesions, or elevated intracranial pressure; exaggerated elevation of ICP may occur.

• Hepatic impairment: Use with caution in patients with hepatic dysfunction.

• Mental health conditions: Use opioids with caution for chronic pain in patients with mental health conditions (eg, depression, anxiety disorders, post-traumatic stress disorder) due to increased risk for opioid use disorder and overdose; more frequent monitoring is recommended (Dowell [CDC 2016]).

• Myocardial infarction (MI): Use with caution in patients with acute MI or MI with nausea/vomiting; hypertension may occur with pentazocine use.

• Porphyria: Use with caution in patients with a history of porphyria; may exacerbate condition.

• Prostatic hyperplasia/urinary stricture: Use with caution in patients with prostatic hyperplasia and/or urinary stricture, especially when combined with medications that have anticholinergic effects.

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

• Respiratory disease: Use with caution in patients with pre-existing respiratory compromise (hypoxia and/or hypercapnia), COPD or other obstructive pulmonary disease, and kyphoscoliosis or other skeletal disorder which may alter respiratory function; critical respiratory depression may occur, even at therapeutic dosages.

• Seizures: Effects may be potentiated when used with other sedatives, including opioids or ethanol.

• Sleep-disordered breathing: Use opioids with caution for chronic pain and titrate dosage cautiously in patients with risk factors for sleep-disordered breathing, including HF and obesity. Avoid opioids in patients with moderate to severe sleep-disordered breathing (Dowell [CDC 2016]).

• Thyroid dysfunction: Use with caution in patients with hypothyroidism.

Concurrent drug therapy issues:

• Drug-drug interactions: Potentially significant interactions may exist, requiring dose or frequency adjustment, additional monitoring, and/or selection of alternative therapy. Consult drug interactions database for more detailed information.

• Sedatives: Effects may be potentiated when used with other sedatives, including opioids or ethanol. In the setting of chronic pain, avoid prescribing opioids and benzodiazepines concurrently whenever possible; epidemiologic studies suggest there is an increased risk for potentially fatal overdose with concurrent use (Dowell [CDC 2016]).

Special populations:

• Debilitated patients: Use with caution in debilitated patients; there is a greater potential for critical respiratory depression, even at therapeutic dosages.

• Elderly: Use with caution in the elderly; may be more sensitive to adverse effects. Use opioids for chronic pain with caution in this age group; monitor closely due to an increased potential for risks, including certain risks such as falls/fracture, cognitive impairment, and constipation. Clearance may also be reduced in older adults (with or without renal impairment) resulting in a narrow therapeutic window and increasing the risk for respiratory depression or overdose (Dowell [CDC 2016]).

• Neonates: Neonatal withdrawal syndrome: After chronic maternal exposure to opioids, neonatal withdrawal syndrome may occur in the newborn; monitor neonate closely. Signs and symptoms include irritability, hyperactivity and abnormal sleep pattern, high pitched cry, tremor, vomiting, diarrhea and failure to gain weight. Onset, duration and severity depend on the drug used, duration of use, maternal dose, and rate of drug elimination by the newborn. Opioid withdrawal syndrome in the neonate, unlike in adults, may be life-threatening and should be treated according to protocols developed by neonatology experts.

• Smokers: Pentazocine clearance may be increased.

Dosage form specific issues:

• Sodium metabisulfite: May contain sodium metabisulfite; may cause allergic-type reactions including anaphylaxis.

Other warnings/precautions:

• Appropriate use: Chronic pain (outside of end-of-life or palliative care, active cancer treatment, sickle cell disease, or medication-assisted treatment for opioid use disorder) in outpatient setting in adults: Opioids should not be used as first-line therapy for chronic pain management (pain >3-month duration or beyond time of normal tissue healing) due to limited short-term benefits, undetermined long-term benefits, and association with serious risks (eg, overdose, MI, auto accidents, risk of developing opioid use disorder). Preferred management includes nonpharmacologic therapy and nonopioid therapy (eg, NSAIDs, acetaminophen, certain anticonvulsants and antidepressants). If opioid therapy is initiated, it should be combined with nonpharmacologic and non-opioid therapy, as appropriate. Prior to initiation, known risks of opioid therapy should be discussed and realistic treatment goals for pain/function should be established, including consideration for discontinuation if benefits do not outweigh risks. Therapy should be continued only if clinically meaningful improvement in pain/function outweighs risks. Therapy should be initiated at the lowest effective dosage using immediate-release opioids (instead of extended-release/long-acting opioids). Risk associated with use increases with higher opioid dosages. Risks and benefits should be re-evaluated when increasing dosage to ≥50 morphine milligram equivalents (MME)/day orally; dosages ≥90 MME/day orally should be avoided unless carefully justified (Dowell [CDC 2016]).

• Dosage limit: Limit acetaminophen dose from all sources (prescription and OTC) to <4 g/day.

• Withdrawal: Concurrent use of agonist/antagonist analgesics may precipitate withdrawal symptoms and/or reduced analgesic efficacy in patients following prolonged therapy with mu opioid agonists. Abrupt discontinuation following prolonged use may also lead to withdrawal symptoms; taper dose to decrease risk of withdrawal symptoms.

Signs or symptoms of hypogonadism or hypoadrenalism (Brennan 2013).

Alternate recommendations: Chronic pain (long-term therapy outside of end-of-life or palliative care, active cancer treatment, sickle cell disease, or medication-assisted treatment for opioid use disorder): Evaluate benefits/risks of opioid therapy within 1 to 4 weeks of treatment initiation and with dose increases. Re-evaluate benefits/risks every 3 months during therapy or more frequently in patients at increased risk of overdose or opioid use disorder. Urine drug testing is recommended prior to initiation and re-checking should be considered at least yearly (includes controlled prescription medications and illicit drugs of abuse). State prescription drug monitoring program (PDMP) data should be reviewed by clinicians prior to initiation and periodically during therapy (frequency ranging from every prescription to every 3 months) (Dowell [CDC 2016]).