Drug Interactions between chlorpheniramine / guaifenesin / phenylephrine and rosiglitazone

GENERALLY AVOID: Alcohol may potentiate some of the pharmacologic effects of CNS-active agents. Use in combination may result in additive central nervous system depression and/or impairment of judgment, thinking, and psychomotor skills.

MANAGEMENT: Patients receiving CNS-active agents should be warned of this interaction and advised to avoid or limit consumption of alcohol. Ambulatory patients should be counseled to avoid hazardous activities requiring complete mental alertness and motor coordination until they know how these agents affect them, and to notify their physician if they experience excessive or prolonged CNS effects that interfere with their normal activities.

GENERALLY AVOID: Alcohol may cause hypoglycemia or hyperglycemia in patients with diabetes. Hypoglycemia most frequently occurs during acute consumption of alcohol. Even modest amounts can lower blood sugar significantly, especially when the alcohol is ingested on an empty stomach or following exercise. The mechanism involves inhibition of both gluconeogenesis as well as the counter-regulatory response to hypoglycemia. Episodes of hypoglycemia may last for 8 to 12 hours after ethanol ingestion. By contrast, chronic alcohol abuse can cause impaired glucose tolerance and hyperglycemia. Moderate alcohol consumption generally does not affect blood glucose levels in patients with well controlled diabetes. A disulfiram-like reaction (e.g., flushing, headache, and nausea) to alcohol has been reported frequently with the use of chlorpropamide and very rarely with other sulfonylureas.

MANAGEMENT: Patients with diabetes should avoid consuming alcohol if their blood glucose is not well controlled, or if they have hypertriglyceridemia, neuropathy, or pancreatitis. Patients with well controlled diabetes should limit their alcohol intake to one drink daily for women and two drinks daily for men (1 drink = 5 oz wine, 12 oz beer, or 1.5 oz distilled spirits) in conjunction with their normal meal plan. Alcohol should not be consumed on an empty stomach or following exercise.

MONITOR: Coadministration of two or more sympathomimetic agents may increase the risk of adverse effects such as nervousness, irritability, and increased heart rate. Central nervous system (CNS) stimulants, particularly amphetamines, can potentiate the adrenergic response to vasopressors and other sympathomimetic agents. Additive increases in blood pressure and heart rate may occur due to enhanced peripheral sympathetic activity.

MANAGEMENT: Caution is advised if two or more sympathomimetic agents are coadministered. Pulse and blood pressure should be closely monitored.

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.

The use of thiazolidinediones, alone or in combination with other antidiabetic agents, has been associated with fluid retention and new onset or exacerbation of heart failure. An increased risk of cardiovascular events (heart failure worsening; new or worsening edema; new or worsening dyspnea; increases in heart failure medication; myocardial infarction; angina; cardiovascular hospitalization and deaths) has been reported with rosiglitazone therapy in type II diabetic patients with New York Heart Association (NYHA) Class I or II congestive heart failure compared to placebo. Likewise, overnight hospitalization for CHF was observed in 9.9% of diabetic patients with NYHA Class II and III heart failure on pioglitazone compared to 4.7% of patients on glyburide. An increased incidence of cardiovascular adverse events including edema and cardiac failure has also been reported in patients receiving a thiazolidinedione in combination with insulin relative to insulin and placebo. Therapy with thiazolidinediones should be administered cautiously and initiated at the lowest recommended dosage in patients with congestive heart failure. Thiazolidinediones are contraindicated for the treatment of patients with NYHA Class III or IV cardiac status. Patients should be monitored for signs of worsening heart failure such as increased dyspnea, edema, and weight gain. Therapy should be discontinued if any deterioration in cardiac status occurs.

Thiazolidinediones exert their hypoglycemic effect only in the presence of insulin. Therefore, these agents should not be used in patients with type I diabetes or for the treatment of diabetic ketoacidosis.

Thiazolidinediones exert their hypoglycemic effect only in the presence of insulin. Therefore, these agents should not be used in patients with type I diabetes or for the treatment of diabetic ketoacidosis.

Safety data from a pooled analysis of 42 randomized, controlled clinical studies suggest that patients treated with rosiglitazone may have an increased risk of myocardial infarction and/or death from heart-related causes. The overall incidence of myocardial ischemia was 1.99% in patients receiving rosiglitazone-containing therapies (n = 8,604) for at least 24 weeks, compared to 1.51% in patients receiving placebo or other antidiabetic therapies (n = 5,633) for a similar duration. The hazard ratio was 1.31 (95% CI, 1.01 to 1.70) for rosiglitazone-treated patients relative to the comparators, which represents a greater than 30% excess risk of myocardial ischemic events in the rosiglitazone group. However, other published and unpublished data from long-term clinical trials of rosiglitazone provide contradictory evidence about the potential risks. Until more data are available, caution may be advisable when rosiglitazone is prescribed to patients with underlying heart disease or a history of myocardial infarction.

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.

Safety data from a pooled analysis of 42 randomized, controlled clinical studies suggest that patients treated with rosiglitazone may have an increased risk of myocardial infarction and/or death from heart-related causes. The overall incidence of myocardial ischemia was 1.99% in patients receiving rosiglitazone-containing therapies (n = 8,604) for at least 24 weeks, compared to 1.51% in patients receiving placebo or other antidiabetic therapies (n = 5,633) for a similar duration. The hazard ratio was 1.31 (95% CI, 1.01 to 1.70) for rosiglitazone-treated patients relative to the comparators, which represents a greater than 30% excess risk of myocardial ischemic events in the rosiglitazone group. However, other published and unpublished data from long-term clinical trials of rosiglitazone provide contradictory evidence about the potential risks. Until more data are available, caution may be advisable when rosiglitazone is prescribed to patients with underlying heart disease or a history of myocardial infarction.

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.

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.

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.

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.

New onset or worsening diabetic macular edema with decreased visual acuity have been reported in postmarketing reports in some diabetic patients who were taking thiazolidinedione drugs. Some patients presented with blurred vision or decreased visual acuity, but some patients appear to have been diagnosed on routine ophthalmologic examination. Most patients had peripheral edema at the time macular edema was diagnosed. Some patients had improvement in their macular edema after discontinuation of their thiazolidinedione. Patients with diabetes should have regular eye exams by an ophthalmologist according to current standards of care. Additionally, any diabetic who reports any kind of visual symptom should be promptly referred to an ophthalmologist, regardless of the patient's underlying medications or other physical findings.

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.

New onset or worsening diabetic macular edema with decreased visual acuity have been reported in postmarketing reports in some diabetic patients who were taking thiazolidinedione drugs. Some patients presented with blurred vision or decreased visual acuity, but some patients appear to have been diagnosed on routine ophthalmologic examination. Most patients had peripheral edema at the time macular edema was diagnosed. Some patients had improvement in their macular edema after discontinuation of their thiazolidinedione. Patients with diabetes should have regular eye exams by an ophthalmologist according to current standards of care. Additionally, any diabetic who reports any kind of visual symptom should be promptly referred to an ophthalmologist, regardless of the patient's underlying medications or other physical findings.

Thiazolidinediones can cause dose-related edema. Therapy with thiazolidinediones should be administered cautiously in patients at risk for congestive heart failure as well as those with fluid overload or other conditions that may be adversely affected by excess fluid such as hypertension. Patients should be monitored for signs and symptoms of heart failure such as dyspnea, swelling of legs or ankles, and weight gain.

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.

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.

Thiazolidinediones can cause dose-related edema. Therapy with thiazolidinediones should be administered cautiously in patients at risk for congestive heart failure as well as those with fluid overload or other conditions that may be adversely affected by excess fluid such as hypertension. Patients should be monitored for signs and symptoms of heart failure such as dyspnea, swelling of legs or ankles, and weight gain.

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.

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.

Initiation of rosiglitazone or pioglitazone therapy is not recommended in patients who exhibit clinical evidence of active liver disease or increased baseline serum transaminase levels (ALT exceeding 2.5 times upper limit of normal). Use of these agents is also not recommended in patients who have experienced jaundice during treatment with troglitazone. The use of troglitazone, another agent in the thiazolidinedione class, has been associated with clinically significant elevations in liver enzymes, reversible jaundice, and idiosyncratic hepatocellular injury including rare cases of liver failure, liver transplants, and death. Injury has occurred after both short- and long-term treatment. While these effects have not been associated with other thiazolidinediones in clinical trials, concerns exist because of their structural similarities. In addition, isolated cases of hepatitis and hepatic enzyme elevations to 3 or more times the upper limit of normal have been reported with both rosiglitazone and pioglitazone during postmarketing use. Rarely, these events have involved hepatic failure with and without fatal outcome, although causality has not been established. Until more safety data are available, patients who are prescribed thiazolidinedione therapy should have serum transaminase levels checked at baseline and periodically thereafter as clinically necessary. Mild to moderate elevations (ALT less than or equal to 2.5 times ULN) require cautious use with more frequent monitoring to determine if the elevations resolve or worsen. Patients who develop potential symptoms of hepatic injury such as unexplained nausea, vomiting, abdominal pain, fatigue, anorexia, and dark urine should have liver enzymes checked. Therapy should be withdrawn if ALT is elevated and persists above 3 times ULN or if jaundice develops.

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.

Thiazolidinediones can cause dose-related weight gain, which may be undesirable in obese patients attempting to lose weight. The mechanism of weight gain is unclear but probably involves a combination of fluid retention and fat accumulation. In postmarketing experience with rosiglitazone, there have been reports of unusually rapid increases in weight, greater than those generally observed in clinical trials. Patients who experience such increases should be assessed for fluid retention and volume-related events such as excessive edema and congestive heart failure.

Thiazolidinediones can cause dose-related edema. Therapy with thiazolidinediones should be administered cautiously in patients at risk for congestive heart failure as well as those with fluid overload or other conditions that may be adversely affected by excess fluid such as hypertension. Patients should be monitored for signs and symptoms of heart failure such as dyspnea, swelling of legs or ankles, and weight gain.

In premenopausal, anovulatory patients with insulin resistance, treatment with thiazolidinediones may result in resumption of ovulation. Due to improved insulin sensitivity, pregnancy can occur if adequate contraception is not used.

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.

Thiazolidinediones can cause dose-related edema. Therapy with thiazolidinediones should be administered cautiously in patients at risk for congestive heart failure as well as those with fluid overload or other conditions that may be adversely affected by excess fluid such as hypertension. Patients should be monitored for signs and symptoms of heart failure such as dyspnea, swelling of legs or ankles, and weight gain.

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.

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.

Thiazolidinediones can cause slight decreases in hemoglobin and hematocrit. In clinical studies, hemoglobin levels were reduced primarily within the first 4 to 12 weeks of therapy but remained relatively constant thereafter. These changes may be related to increased plasma volume and have rarely been associated with any significant hematologic clinical effects. Nevertheless, caution may be advisable when thiazolidinediones are prescribed to patients with certain anemias.