In patients with severe hepatic or renal disease, effects of therapy should be followed with serial liver and/or renal function tests.
Inhibitors of CYP3A4 and CYP2D6
The concomitant use of hydrocodone bitartrate and acetaminophen tablets and CYP3A4 inhibitors, such as macrolide antibiotics (e.g., erythromycin), azole-antifungal agents (e.g., ketoconazole), and protease inhibitors (e.g., ritonavir), can increase the plasma concentration of the hydrocodone from hydrocodone bitartrate and acetaminophen tablets, resulting in increased or prolonged opioid effects. These effects could be more pronounced with concomitant use of hydrocodone bitartrate and acetaminophen tablets and both CYP3A4 and CYP2D6 inhibitors, particularly when an inhibitor is added after a stable dose of hydrocodone bitartrate and acetaminophen tablets is achieved ( see WARNINGS).
After stopping a CYP3A4 inhibitor, as the effects of the inhibitor decline, the hydrocodone plasma concentration will decrease ( see CLINICAL PHARMACOLOGY), resulting in decreased opioid efficacy or a withdrawal syndrome in patients who had developed physical dependence to hydrocodone bitartrate and acetaminophen tablets.
If concomitant use is necessary, consider dosage reduction of hydrocodone bitartrate and acetaminophen tablets until stable drug effects are achieved. Follow patients for respiratory depression and sedation at frequent intervals. If a CYP3A4 inhibitor is discontinued, consider increasing the hydrocodone bitartrate and acetaminophen tablets dosage until stable drug effects are achieved. Follow for signs or symptoms of opioid withdrawal.
Inducers of CYP3A4
The concomitant use of hydrocodone bitartrate and acetaminophen tablets and CYP3A4 inducers, such as rifampin, carbamazepine, and phenytoin, can decrease the plasma concentration of hydrocodone ( see CLINICAL PHARMACOLOGY), resulting in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence to hydrocodone ( see WARNINGS).
After stopping a CYP3A4 inducer, as the effects of the inducer decline, the hydrocodone plasma concentration will increase ( see CLINICAL PHARMACOLOGY), which could increase or prolong both the therapeutic effects and adverse reactions, and may cause serious respiratory depression.
If concomitant use is necessary, consider increasing the hydrocodone bitartrate and acetaminophen tablets dosage until stable drug effects are achieved. Follow the patient for signs and symptoms of opioid withdrawal. If a CYP3A4 inducer is discontinued, consider hydrocodone bitartrate and acetaminophen tablets dosage reduction and follow for signs of respiratory depression.
Benzodiazepines and Other CNS Depressants
Due to additive pharmacologic effect, the concomitant use of benzodiazepines and other CNS depressants, such as benzodiazepines and other sedative hypnotics, anxiolytics, and tranquilizers, muscle relaxants, general anesthetics, antipsychotics, and other opioids, including alcohol, can increase the risk of hypotension, respiratory depression, profound sedation, coma, and death.
Reserve concomitant prescribing of these drugs for use in patients for whom alternative treatment options are inadequate. Limit dosages and durations to the minimum required. Follow patients closely for signs of respiratory depression and sedation ( see WARNINGS).
The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system, such as selective serotonin reuptake inhibitors (SSRIs), serotonin and norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants (TCAs), triptans, 5-HT3 receptor antagonists, drugs that affect the serotonin neurotransmitter system (e.g., mirtazapine, trazodone, tramadol), certain muscle relaxants (i.e., cyclobenzaprine, metaxalone), and monoamine oxidase (MAO) inhibitors (those intended to treat psychiatric disorders and also others, such as linezolid and intravenous methylene blue), has resulted in serotonin syndrome ( see PRECAUTIONS, Information for Patients).
If concomitant use is warranted, carefully follow the patient, particularly during treatment initiation and dose adjustment. Discontinue hydrocodone bitartrate and acetaminophen tablets if serotonin syndrome is suspected.
Monoamine Oxidase Inhibitors (MAOIs)
The concomitant use of opioids and MAOIs, such as phenelzine, tranylcypromine, or linezolid, may manifest as serotonin syndrome, or opioid toxicity (e.g., respiratory depression, coma) ( see WARNINGS).
The use of hydrocodone bitartrate and acetaminophen tablets is not recommended for patients taking MAOIs or within 14 days of stopping such treatment.
If urgent use of an opioid is necessary, use test doses and frequent titration of small doses to treat pain while closely monitoring blood pressure and signs and symptoms of CNS and respiratory depression.
Mixed Agonist/Antagonist and Partial Agonist Opioid Analgesics
The concomitant use of opioids with other opioid analgesics, such as butorphanol, nalbuphine, pentazocine, may reduce the analgesic effect of hydrocodone bitartrate and acetaminophen tablets and/or precipitate withdrawal symptoms.
Advise patient to avoid concomitant use of these drugs.
Hydrocodone bitartrate and acetaminophen tablets may enhance the neuromuscular blocking action of skeletal muscle relaxants and produce an increased degree of respiratory depression.
If concomitant use is warranted, monitor patients for signs of respiratory depression that may be greater than otherwise expected and decrease the dosage of hydrocodone bitartrate and acetaminophen tablets and/or the muscle relaxant as necessary.
Opioids can reduce the efficacy of diuretics by inducing the release of antidiuretic hormone.
If concomitant use is warranted, follow patients for signs of diminished diuresis and/or effects on blood pressure and increase the dosage of the diuretic as needed.
The concomitant use of anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus.
If concomitant use is warranted, follow patients for signs and symptoms of urinary retention or reduced gastric motility when hydrocodone bitartrate and acetaminophen tablets are used concomitantly with anticholinergic drugs.
Acetaminophen may produce false-positive test results for urinary 5-hydroxyindoleacetic acid.
Long-term studies to evaluate the carcinogenic potential of the combination of hydrocodone bitartrate and acetaminophen tablets have not been conducted.
Long-term studies in mice and rats have been completed by the National Toxicology Program to evaluate the carcinogenic potential of acetaminophen. In 2-year feeding studies, F344/N rats and B6C3F1 mice were fed a diet containing acetaminophen up to 6000 ppm. Female rats demonstrated equivocal evidence of carcinogenic activity based on increased incidences of mononuclear cell leukemia at 0.8 times the maximum human daily dose (MHDD) of 4 grams/day, based on a body surface area comparison. In contrast, there was no evidence of carcinogenic activity in male rats that received up to 0.7 times or mice at up to 1.2 to 1.4 times the MHDD, based on a body surface area comparison.
In the published literature, acetaminophen has been reported to be clastogenic when administered at 1500 mg/kg/day to the rat model (3.6 times the MHDD, based on a body surface area comparison). In contrast, no clastogenicity was noted at a dose of 750 mg/kg/day (1.8 times the MHDD, based on a body surface area comparison), suggesting a threshold effect.
Impairment of Fertility
In studies conducted by the National Toxicology Program, fertility assessments with acetaminophen have been completed in Swiss CD-1 mice via a continuous breeding study. There were no effects on fertility parameters in mice consuming up to 1.7 times the MHDD of acetaminophen, based on a body surface area comparison. Although there was no effect on sperm motility or sperm density in the epididymis, there was a significant increase in the percentage of abnormal sperm in mice consuming 1.78 times the MHDD (based on a body surface comparison) and there was a reduction in the number of mating pairs producing a fifth litter at this dose, suggesting the potential for cumulative toxicity with chronic administration of acetaminophen near the upper limit of daily dosing.
Published studies in rodents report that oral acetaminophen treatment of male animals at doses that are 1.2 times the MHDD and greater (based on a body surface comparison) result in decreased testicular weights, reduced spermatogenesis, reduced fertility, and reduced implantation sites in females given the same doses. These effects appear to increase with the duration of treatment. The clinical significance of these findings is not known.
Chronic use of opioids may cause reduced fertility in females and males of reproductive potential. It is not known whether these effects on fertility are reversible ( see ADVERSE REACTIONS).
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