Aluminum hydroxide/diphenhydramine/lidocaine/magnesium hydroxide/simethicone topical Disease Interactions

Aluminum containing antacids may produce constipation, which may lead to intestinal obstruction. Osteomalacia and hypophosphatemia may be produced in patients with renal dysfunction who are not receiving dialysis. Patients with renal dysfunction, intestinal obstruction, osteomalacia, or hypophosphatemia should use antacids with low or no aluminum content.

A variety of abnormal thinking and behavior changes have been reported to occur in association with the use of most anxiolytics, sedatives and hypnotics. Some of these changes include decreased inhibition, aggressiveness, agitation, and hallucinations. These drugs can cause or exacerbate mental depression and cause suicidal behavior and ideation. Therapy with these drugs should be administered cautiously in patients with a history of depression or other psychiatric disorders. Patients should be monitored for any changes in mood or behavior. It may be prudent to refrain from dispensing large quantities of medication to these patients.

The use of laxatives is contraindicated in patients with inflammatory bowel disease. Patients with inflammatory bowel disease may experience colonic perforation with use of stimulant laxatives.

The use of laxatives is contraindicated in patients with intestinal obstruction disorders. Patients with intestinal obstruction disorders may need their underlying condition treated to correct the constipation. Some laxatives require reduction in the colon to their active form to be effective which may be a problem in patients with intestinal obstruction.

Topical lidocaine is not recommended to be used in teething infants and young children, as its ingestion is dangerous and potentially fatal. Ingestion of the drug has shown to result in seizures, severe brain injury, and heart problems in children.

Lidocaine is absorbed through intact skin and mucosal membranes following topical administration. Prolonged exposure, large doses, frequent applications and/or use on compromised skin or mucosa can produce systemic effects. At high plasma levels, lidocaine can cause hypotension, bradycardia, and cardiovascular collapse. Therapy with lidocaine topical should be administered cautiously in patients with shock, sinus bradyarrhythmia, or severe heart block. The recommended dosage should not be exceeded. Children and debilitated, elderly, or acutely ill patients should be given reduced dosages commensurate with their age, weight, and physical condition.

Lidocaine topical is absorbed through intact skin and mucosal membranes. Prolonged exposure, large doses, and/or application to compromised skin or mucosa can result in elevated plasma concentrations of lidocaine. Lidocaine is rapidly and extensively metabolized by the liver. Less than 10% is eliminated unchanged in the urine. Several inactive and two active forms (MEGX and GX) have been identified. MEGX and GX exhibit antiarrhythmic and convulsant properties. The pharmacokinetic disposition of lidocaine is altered by changes in hepatic function, including hepatic blood flow. Therapy with lidocaine topical should be administered cautiously and dosing modified for patients with compromised hepatic function.

Lidocaine topical is absorbed through intact skin and mucosal membranes. Prolonged exposure, large doses, and/or application to compromised skin or mucosa can result in elevated plasma concentrations of lidocaine. Lidocaine is primarily eliminated by the kidney. Less than 10% is eliminated unchanged in the urine. Two active metabolites (MEGX and GX) have been identified that exhibit antiarrhythmic and convulsant properties. Serum concentrations of lidocaine and the active metabolites are increased and the half-life prolonged in patients with renal impairment. Therapy with lidocaine topical should be administered cautiously and dosing modified for repeated doses in patients with compromised renal function.

Lidocaine topical is absorbed through intact skin and mucosal membranes. Prolonged exposure, large doses, and/or application to compromised skin or mucosa can result in elevated plasma concentrations of lidocaine. Seizures can occur as a result of accumulation of active metabolites. Therapy with lidocaine topical should be administered cautiously to patients with or predisposed to seizure disorders.

Magnesium is eliminated by the kidney. The serum concentration of magnesium is increased in patients with renal impairment. Magnesium toxicity includes CNS depression, muscular paralysis, respiratory depression, hypotension and prolonged cardiac conduction time. Disappearance of the patellar reflex is a useful clinical sign of magnesium intoxication. Therapy with magnesium should be administered cautiously and dosages should be modified in patients with compromised renal function. Clinical monitoring of serum magnesium levels is recommended.

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.

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.

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.

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.

Some hypnotic drugs can have an anticholinergic effect and should be used with caution in patients with glaucoma, and trouble urinating due to retention or enlarged prostate.

In general, anxiolytics, sedatives and hypnotics are extensively metabolized by the liver. Their plasma clearance may be decreased and their half-life prolonged in patients with impaired hepatic function. Therapy with these drugs should be administered cautiously in patients with liver disease (some are not recommended in severe liver impairment), and the dosage should be adjusted accordingly. Laboratory testing is recommended prior and during treatment.

Oral anxiolytic, sedative, and hypnotic agents may cause respiratory depression and apnea when given in high dosages or following acute overdose. However, some patients may be susceptible at commonly used dosages, including the elderly, debilitated or severely ill patients, those receiving other CNS depressants, and those with limited ventilatory reserve, chronic pulmonary insufficiency or other respiratory disorders. Therapy with anxiolytic, sedative, and hypnotic agents should be administered cautiously in these patients. Appropriate monitoring and individualization of dosage are recommended.