Drug Interactions between chlorpheniramine / guaifenesin / phenylephrine and linezolid

During and within two weeks after treatment with linezolid, you must not consume any foods or beverages that are high in tyramine content. Doing so can raise your blood pressure to dangerous levels, a condition known as hypertensive crisis. The condition is potentially fatal and may cause symptoms such as severe headache, confusion, blurred vision, problems with speech or balance, nausea, vomiting, chest pain, convulsions, and sudden numbness or weakness (especially on one side of the body). You should seek immediate medical attention if you have any of these symptoms. Foods that are high in tyramine include, but are not limited to, air dried meats; aged or fermented meats; sausage or salami; pickled herring; anchovies; liver; red wine; beer; aged cheeses, including blue, brick, brie, cheddar, parmesan, romano, and swiss; sour cream; sauerkraut; canned figs; raisins; bananas or avocados (particularly if overripe); soy beans; soy sauce; tofu; miso soup; bean curd; fava beans; or yeast extracts (such as Marmite). You should avoid the use of alcohol while being treated with linezolid, as alcohol may increase some of the nervous system side effects such as dizziness, drowsiness, and difficulty concentrating. Also avoid activities requiring mental alertness such as driving or operating hazardous machinery until you know how the medication affects you. Talk to your doctor or pharmacist if you have any questions or concerns.

Alcohol can increase the nervous system side effects of chlorpheniramine such as dizziness, drowsiness, and difficulty concentrating. Some people may also experience impairment in thinking and judgment. You should avoid or limit the use of alcohol while being treated with chlorpheniramine. Do not use more than the recommended dose of chlorpheniramine, and avoid activities requiring mental alertness such as driving or operating hazardous machinery until you know how the medication affects you. Talk to your doctor or pharmacist if you have any questions or concerns.

Both phenylephrine and caffeine can increase blood pressure and heart rate, and combining them may enhance these effects. Talk to your doctor before using these medications, especially if you have a history of high blood pressure or heart disease. You may need a dose adjustment or more frequent monitoring by your doctor to safely use both medications. Contact your doctor if your condition changes or you experience increased side effects. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

Reversible myelosuppression, including anemia, leukopenia, pancytopenia and thrombocytopenia, has been reported during postmarketing use of linezolid, although a causal relationship has not been established. Thrombocytopenia was also reported in phase 3 comparator-controlled trials at dosages up to and including 600 mg every 12 hours for up to 28 days, and bleeding events were identified in thrombocytopenic patients in a compassionate use program for linezolid. Therapy with linezolid should be administered cautiously in patients with preexisting blood dyscrasias and in patients receiving concomitant medications that may produce myelosuppression. Complete blood counts should be monitored weekly, particularly if linezolid is administered for longer than 2 weeks. Discontinuation of therapy should be considered in patients who develop or have worsening myelosuppression.

Sympathomimetic agents may cause adverse cardiovascular effects, particularly when used in high dosages and/or in susceptible patients. In cardiac tissues, these agents may produce positive chronotropic and inotropic effects via stimulation of beta- 1 adrenergic receptors. Cardiac output, oxygen consumption, and the work of the heart may be increased. In the peripheral vasculature, vasoconstriction may occur via stimulation of alpha-1 adrenergic receptors. Palpitations, tachycardia, arrhythmia, hypertension, reflex bradycardia, coronary occlusion, cerebral vasculitis, myocardial infarction, cardiac arrest, and death have been reported. Some of these agents, particularly ephedra alkaloids (ephedrine, ma huang, phenylpropanolamine), may also predispose patients to hemorrhagic and ischemic stroke. Therapy with sympathomimetic agents should generally be avoided or administered cautiously in patients with sensitivity to sympathomimetic amines, hyperthyroidism, or underlying cardiovascular or cerebrovascular disorders. These agents should not be used in patients with severe coronary artery disease or severe/uncontrolled hypertension.

Sympathomimetic agents may cause adverse cardiovascular effects, particularly when used in high dosages and/or in susceptible patients. In cardiac tissues, these agents may produce positive chronotropic and inotropic effects via stimulation of beta- 1 adrenergic receptors. Cardiac output, oxygen consumption, and the work of the heart may be increased. In the peripheral vasculature, vasoconstriction may occur via stimulation of alpha-1 adrenergic receptors. Palpitations, tachycardia, arrhythmia, hypertension, reflex bradycardia, coronary occlusion, cerebral vasculitis, myocardial infarction, cardiac arrest, and death have been reported. Some of these agents, particularly ephedra alkaloids (ephedrine, ma huang, phenylpropanolamine), may also predispose patients to hemorrhagic and ischemic stroke. Therapy with sympathomimetic agents should generally be avoided or administered cautiously in patients with sensitivity to sympathomimetic amines, hyperthyroidism, or underlying cardiovascular or cerebrovascular disorders. These agents should not be used in patients with severe coronary artery disease or severe/uncontrolled hypertension.

Clostridioides difficile-associated diarrhea (CDAD), formerly pseudomembranous colitis, has been reported with almost all antibacterial drugs and may range from mild diarrhea to fatal colitis. The most common culprits include clindamycin and lincomycin. Antibacterial therapy alters the normal flora of the colon, leading to overgrowth of C difficile, whose toxins A and B contribute to CDAD development. Morbidity and mortality are increased with hypertoxin-producing strains of C difficile; these infections can be resistant to antimicrobial therapy and may require colectomy. CDAD must be considered in all patients who present with diarrhea after antibacterial use. Since CDAD has been reported to occur more than 2 months after antibacterial use, careful medical history is necessary. Therapy with broad-spectrum antibacterials and other agents with significant antibacterial activity should be administered cautiously in patients with history of gastrointestinal disease, particularly colitis; pseudomembranous colitis (generally characterized by severe, persistent diarrhea and severe abdominal cramps, and sometimes associated with the passage of blood and mucus), if it occurs, may be more severe in these patients and may be associated with flares in underlying disease activity. Antibacterial drugs not directed against C difficile may need to be stopped if CDAD is suspected or confirmed. Appropriate fluid and electrolyte management, protein supplementation, antibacterial treatment of C difficile, and surgical evaluation should be started as clinically indicated.

Sympathomimetic agents may cause adverse cardiovascular effects, particularly when used in high dosages and/or in susceptible patients. In cardiac tissues, these agents may produce positive chronotropic and inotropic effects via stimulation of beta- 1 adrenergic receptors. Cardiac output, oxygen consumption, and the work of the heart may be increased. In the peripheral vasculature, vasoconstriction may occur via stimulation of alpha-1 adrenergic receptors. Palpitations, tachycardia, arrhythmia, hypertension, reflex bradycardia, coronary occlusion, cerebral vasculitis, myocardial infarction, cardiac arrest, and death have been reported. Some of these agents, particularly ephedra alkaloids (ephedrine, ma huang, phenylpropanolamine), may also predispose patients to hemorrhagic and ischemic stroke. Therapy with sympathomimetic agents should generally be avoided or administered cautiously in patients with sensitivity to sympathomimetic amines, hyperthyroidism, or underlying cardiovascular or cerebrovascular disorders. These agents should not be used in patients with severe coronary artery disease or severe/uncontrolled hypertension.

Sympathomimetic agents may cause adverse cardiovascular effects, particularly when used in high dosages and/or in susceptible patients. In cardiac tissues, these agents may produce positive chronotropic and inotropic effects via stimulation of beta- 1 adrenergic receptors. Cardiac output, oxygen consumption, and the work of the heart may be increased. In the peripheral vasculature, vasoconstriction may occur via stimulation of alpha-1 adrenergic receptors. Palpitations, tachycardia, arrhythmia, hypertension, reflex bradycardia, coronary occlusion, cerebral vasculitis, myocardial infarction, cardiac arrest, and death have been reported. Some of these agents, particularly ephedra alkaloids (ephedrine, ma huang, phenylpropanolamine), may also predispose patients to hemorrhagic and ischemic stroke. Therapy with sympathomimetic agents should generally be avoided or administered cautiously in patients with sensitivity to sympathomimetic amines, hyperthyroidism, or underlying cardiovascular or cerebrovascular disorders. These agents should not be used in patients with severe coronary artery disease or severe/uncontrolled hypertension.

Reversible myelosuppression, including anemia, leukopenia, pancytopenia and thrombocytopenia, has been reported during postmarketing use of linezolid, although a causal relationship has not been established. Thrombocytopenia was also reported in phase 3 comparator-controlled trials at dosages up to and including 600 mg every 12 hours for up to 28 days, and bleeding events were identified in thrombocytopenic patients in a compassionate use program for linezolid. Therapy with linezolid should be administered cautiously in patients with preexisting blood dyscrasias and in patients receiving concomitant medications that may produce myelosuppression. Complete blood counts should be monitored weekly, particularly if linezolid is administered for longer than 2 weeks. Discontinuation of therapy should be considered in patients who develop or have worsening myelosuppression.

Cases of lactic acidosis have been reported with the use of linezolid. Patients who develop recurrent nausea or vomiting, unexplained acidosis, or a low bicarbonate level while receiving linezolid should receive immediate medical evaluation.

It has been suggested that the anticholinergic effect of antihistamines may reduce the volume and cause thickening of bronchial secretions, resulting in obstruction of respiratory tract. Some manufacturers and clinicians recommend that therapy with antihistamines be administered cautiously in patients with asthma or chronic obstructive pulmonary disease.

Sympathomimetic agents may cause or worsen urinary difficulty in patients with prostate enlargement due to smooth muscle contraction in the bladder neck via stimulation of alpha-1 adrenergic receptors. Therapy with sympathomimetic agents should be administered cautiously in patients with hypertrophy or neoplasm of the prostate.

Linezolid is a weak, reversible, nonselective monoamine oxidase inhibitor (MAOI). Nonspecific MAOIs inhibit the breakdown of pressor amines, including serotonin, and may exacerbate symptoms of the carcinoid syndrome. While adverse effects related to MAOI activity have not been reported with linezolid, the potential for excessive serotonergic effects should be considered. Therapy with linezolid should be administered cautiously in patients with carcinoid syndrome and in patients receiving serotonergic agents. Clinical data are not available concerning the use of linezolid in these populations.

Antihistamines may infrequently cause cardiovascular adverse effects related to their anticholinergic and local anesthetic (quinidine-like) activities. Tachycardia, palpitation, ECG changes, arrhythmias, hypotension, and hypertension have been reported. Although these effects are uncommon and usually limited to overdosage situations, the manufacturers and some clinicians recommend that therapy with antihistamines be administered cautiously in patients with cardiovascular disease, hypertension, and/or hyperthyroidism.

Linezolid is a weak, reversible, nonselective monoamine oxidase inhibitor (MAOI). Nonspecific MAOIs inhibit the breakdown of pressor amines, the accumulation of which can precipitate hypertensive crises. Intracranial hemorrhage and death have been reported with MAOI antidepressants. While adverse effects related to MAOI activity have not been reported with linezolid, the potential for severe hypertension should be considered. Therapy with linezolid should be administered cautiously in patients with cerebro- or cardiovascular disease, pheochromocytoma, or untreated hyperthyroidism. Clinical data are not available concerning the use of linezolid in this population. As a precaution, patients should have their blood pressure monitored during therapy and observed for signs and symptoms of a hypertensive reaction (e.g., occipital headache which may radiate frontally; palpitation; neck stiffness or soreness; nausea or vomiting; perspiration associated with fever or cold, clammy skin; mydriasis; photophobia; constricting chest pain).

Linezolid is a weak, reversible, nonselective monoamine oxidase inhibitor (MAOI). Nonspecific MAOIs inhibit the breakdown of pressor amines, the accumulation of which can precipitate hypertensive crises. Intracranial hemorrhage and death have been reported with MAOI antidepressants. While adverse effects related to MAOI activity have not been reported with linezolid, the potential for severe hypertension should be considered. Therapy with linezolid should be administered cautiously in patients with cerebro- or cardiovascular disease, pheochromocytoma, or untreated hyperthyroidism. Clinical data are not available concerning the use of linezolid in this population. As a precaution, patients should have their blood pressure monitored during therapy and observed for signs and symptoms of a hypertensive reaction (e.g., occipital headache which may radiate frontally; palpitation; neck stiffness or soreness; nausea or vomiting; perspiration associated with fever or cold, clammy skin; mydriasis; photophobia; constricting chest pain).

It has been suggested that the anticholinergic effect of antihistamines may reduce the volume and cause thickening of bronchial secretions, resulting in obstruction of respiratory tract. Some manufacturers and clinicians recommend that therapy with antihistamines be administered cautiously in patients with asthma or chronic obstructive pulmonary disease.

Cases of symptomatic hypoglycemia have been reported in diabetic patients receiving insulin or oral hypoglycemic agents when treated with linezolid. Caution and close monitoring are recommended when prescribing this agent to a patient with diabetes mellitus.

Sympathomimetic agents may cause increases in blood glucose concentrations. These effects are usually transient and slight but may be significant with dosages higher than those normally recommended. Therapy with sympathomimetic agents should be administered cautiously in patients with diabetes mellitus. Closer monitoring of blood glucose concentrations may be appropriate.

Antihistamines often have anticholinergic activity, to which elderly patients are particularly sensitive. Therapy with antihistamines should be administered cautiously, if at all, in patients with preexisting conditions that are likely to be exacerbated by anticholinergic activity, such as urinary retention or obstruction; angle-closure glaucoma, untreated intraocular hypertension, or uncontrolled primary open-angle glaucoma; and gastrointestinal obstructive disorders. Conventional, first-generation antihistamines such as the ethanolamines (bromodiphenhydramine, carbinoxamine, clemastine, dimenhydrinate, diphenhydramine, doxylamine, phenyltoloxamine) tend to exhibit substantial anticholinergic effects. In contrast, the newer, relatively nonsedating antihistamines (e.g., cetirizine, fexofenadine, loratadine) reportedly have low to minimal anticholinergic activity at normally recommended dosages and may be appropriate alternatives.

Antihistamines often have anticholinergic activity, to which elderly patients are particularly sensitive. Therapy with antihistamines should be administered cautiously, if at all, in patients with preexisting conditions that are likely to be exacerbated by anticholinergic activity, such as urinary retention or obstruction; angle-closure glaucoma, untreated intraocular hypertension, or uncontrolled primary open-angle glaucoma; and gastrointestinal obstructive disorders. Conventional, first-generation antihistamines such as the ethanolamines (bromodiphenhydramine, carbinoxamine, clemastine, dimenhydrinate, diphenhydramine, doxylamine, phenyltoloxamine) tend to exhibit substantial anticholinergic effects. In contrast, the newer, relatively nonsedating antihistamines (e.g., cetirizine, fexofenadine, loratadine) reportedly have low to minimal anticholinergic activity at normally recommended dosages and may be appropriate alternatives.

Sympathomimetic agents can induce transient mydriasis via stimulation of alpha-1 adrenergic receptors. In patients with anatomically narrow angles or narrow-angle glaucoma, pupillary dilation can provoke an acute attack. In patients with other forms of glaucoma, mydriasis may occasionally increase intraocular pressure. Therapy with sympathomimetic agents should be administered cautiously in patients with or predisposed to glaucoma, particularly narrow-angle glaucoma.

Caution is recommended when prescribing linezolid to patients with a history of seizures or risk factors for seizures as convulsions have been reported with the use of this agent. Close monitoring is recommended.

Linezolid is partially removed by hemodialysis and should be administered after dialysis.

Linezolid should not be administered to patients with uncontrolled hypertension, pheochromocytoma, thyrotoxicosis and/or patients taking any medication that could affect the pressor response unless patients are being monitored for potential increases in blood pressure. Caution and close monitoring are recommended when prescribing this agent to these patients.

Antihistamines may infrequently cause cardiovascular adverse effects related to their anticholinergic and local anesthetic (quinidine-like) activities. Tachycardia, palpitation, ECG changes, arrhythmias, hypotension, and hypertension have been reported. Although these effects are uncommon and usually limited to overdosage situations, the manufacturers and some clinicians recommend that therapy with antihistamines be administered cautiously in patients with cardiovascular disease, hypertension, and/or hyperthyroidism.

Linezolid is a weak, reversible, nonselective monoamine oxidase inhibitor (MAOI). Nonspecific MAOIs inhibit the breakdown of pressor amines, the accumulation of which can precipitate hypertensive crises. Intracranial hemorrhage and death have been reported with MAOI antidepressants. While adverse effects related to MAOI activity have not been reported with linezolid, the potential for severe hypertension should be considered. Therapy with linezolid should be administered cautiously in patients with cerebro- or cardiovascular disease, pheochromocytoma, or untreated hyperthyroidism. Clinical data are not available concerning the use of linezolid in this population. As a precaution, patients should have their blood pressure monitored during therapy and observed for signs and symptoms of a hypertensive reaction (e.g., occipital headache which may radiate frontally; palpitation; neck stiffness or soreness; nausea or vomiting; perspiration associated with fever or cold, clammy skin; mydriasis; photophobia; constricting chest pain).

Antihistamines may infrequently cause cardiovascular adverse effects related to their anticholinergic and local anesthetic (quinidine-like) activities. Tachycardia, palpitation, ECG changes, arrhythmias, hypotension, and hypertension have been reported. Although these effects are uncommon and usually limited to overdosage situations, the manufacturers and some clinicians recommend that therapy with antihistamines be administered cautiously in patients with cardiovascular disease, hypertension, and/or hyperthyroidism.

Linezolid is primarily metabolized by the liver. The pharmacokinetics of linezolid are not altered in patients with mild to moderate hepatic impairment (Child-Pugh class A or B) and, therefore, no dosage adjustments are necessary. Pharmacokinetic data are not available for patients with severe hepatic impairment. Therapy with linezolid should be administered cautiously in such patients.

Limited pharmacokinetic data are available for the older, first-generation antihistamines. Many appear to be primarily metabolized by the liver, and both parent drugs and metabolites are excreted in the urine. Patients with renal and/or liver disease may be at greater risk for adverse effects from antihistamines due to drug and metabolite accumulation. Therapy with antihistamines should be administered cautiously in such patients. Lower initial dosages may be appropriate.

Peripheral and optic neuropathies have been reported in patients treated with linezolid. If patients experience symptoms of visual impairment, such as changes in visual acuity, changes in color vision, blurred vision, or visual field defect, prompt ophthalmic evaluation is recommended. Visual function should be monitored in all patients taking linezolid for extended periods and in all patients reporting new visual symptoms regardless of length of therapy with linezolid. If peripheral or optic neuropathy occurs, the continued use of linezolid in these patients should be weighed against the potential risks.

Peripheral and optic neuropathies have been reported in patients treated with linezolid. If patients experience symptoms of visual impairment, such as changes in visual acuity, changes in color vision, blurred vision, or visual field defect, prompt ophthalmic evaluation is recommended. Visual function should be monitored in all patients taking linezolid for extended periods and in all patients reporting new visual symptoms regardless of length of therapy with linezolid. If peripheral or optic neuropathy occurs, the continued use of linezolid in these patients should be weighed against the potential risks.

Linezolid is a weak, reversible, nonselective monoamine oxidase inhibitor (MAOI). Nonspecific MAOIs inhibit the breakdown of pressor amines, the accumulation of which can precipitate hypertensive crises. Intracranial hemorrhage and death have been reported with MAOI antidepressants. While adverse effects related to MAOI activity have not been reported with linezolid, the potential for severe hypertension should be considered. Therapy with linezolid should be administered cautiously in patients with cerebro- or cardiovascular disease, pheochromocytoma, or untreated hyperthyroidism. Clinical data are not available concerning the use of linezolid in this population. As a precaution, patients should have their blood pressure monitored during therapy and observed for signs and symptoms of a hypertensive reaction (e.g., occipital headache which may radiate frontally; palpitation; neck stiffness or soreness; nausea or vomiting; perspiration associated with fever or cold, clammy skin; mydriasis; photophobia; constricting chest pain).

Linezolid should not be administered to patients with uncontrolled hypertension, pheochromocytoma, thyrotoxicosis and/or patients taking any medication that could affect the pressor response unless patients are being monitored for potential increases in blood pressure. Caution and close monitoring are recommended when prescribing this agent to these patients.

Sympathomimetic agents may cause or worsen urinary difficulty in patients with prostate enlargement due to smooth muscle contraction in the bladder neck via stimulation of alpha-1 adrenergic receptors. Therapy with sympathomimetic agents should be administered cautiously in patients with hypertrophy or neoplasm of the prostate.

Linezolid is primarily metabolized by the liver and subsequently eliminated by the kidney. The pharmacokinetics of the parent drug are not altered in patients with impaired renal function and, therefore, no dosage adjustments are necessary. However, accumulation of the two primary metabolites may occur in such patients, the amount of which increases with the degree of renal impairment. The clinical significance of metabolite accumulation has not been determined. Therapy with linezolid should be administered cautiously in patients with renal impairment and only if benefits outweigh the potential risks.

Limited pharmacokinetic data are available for the older, first-generation antihistamines. Many appear to be primarily metabolized by the liver, and both parent drugs and metabolites are excreted in the urine. Patients with renal and/or liver disease may be at greater risk for adverse effects from antihistamines due to drug and metabolite accumulation. Therapy with antihistamines should be administered cautiously in such patients. Lower initial dosages may be appropriate.

Caution is recommended when prescribing linezolid to patients with a history of seizures or risk factors for seizures as convulsions have been reported with the use of this agent. Close monitoring is recommended.

Linezolid should not be administered to patients with uncontrolled hypertension, pheochromocytoma, thyrotoxicosis and/or patients taking any medication that could affect the pressor response unless patients are being monitored for potential increases in blood pressure. Caution and close monitoring are recommended when prescribing this agent to these patients.

Antihistamines often have anticholinergic activity, to which elderly patients are particularly sensitive. Therapy with antihistamines should be administered cautiously, if at all, in patients with preexisting conditions that are likely to be exacerbated by anticholinergic activity, such as urinary retention or obstruction; angle-closure glaucoma, untreated intraocular hypertension, or uncontrolled primary open-angle glaucoma; and gastrointestinal obstructive disorders. Conventional, first-generation antihistamines such as the ethanolamines (bromodiphenhydramine, carbinoxamine, clemastine, dimenhydrinate, diphenhydramine, doxylamine, phenyltoloxamine) tend to exhibit substantial anticholinergic effects. In contrast, the newer, relatively nonsedating antihistamines (e.g., cetirizine, fexofenadine, loratadine) reportedly have low to minimal anticholinergic activity at normally recommended dosages and may be appropriate alternatives.

Cases of lactic acidosis have been reported with the use of linezolid. Patients who develop recurrent nausea or vomiting, unexplained acidosis, or a low bicarbonate level while receiving linezolid should receive immediate medical evaluation.