LOMOTIL- diphenoxylate hydrochloride and atropine sulfate tablet
Pfizer Laboratories Div Pfizer Inc
Each Lomotil tablet contains:
2.5 mg of diphenoxylate hydrochloride USP (equivalent to 2.3 mg of diphenoxylate) and 0.025 mg of atropine sulfate USP (equivalent to 0.01 mg of atropine)
Diphenoxylate hydrochloride, an antidiarrheal, is ethyl 1-(3-cyano-3,3-diphenylpropyl)-4-phenylisonipecotate monohydrochloride and has the following structural formula:
Atropine sulfate, an anticholinergic, is endo-(±)-α-(hydroxymethyl) benzeneacetic acid 8-methyl-8-azabicyclo[3.2.1] oct-3-yl ester sulfate (2:1) (salt) monohydrate and has the following structural formula:
A subtherapeutic amount of atropine sulfate is present to discourage deliberate overdosage.
Inactive ingredients of Lomotil tablets include acacia, corn starch, magnesium stearate, sorbitol, sucrose, and talc.
Diphenoxylate is rapidly and extensively metabolized in man by ester hydrolysis to diphenoxylic acid (difenoxine), which is biologically active and the major metabolite in the blood. After a 5 mg oral dose of carbon-14 labeled diphenoxylate hydrochloride in ethanolic solution was given to three healthy volunteers, an average of 14% of the drug plus its metabolites was excreted in the urine and 49% in the feces over a four-day period. Urinary excretion of the unmetabolized drug constituted less than 1% of the dose, and diphenoxylic acid plus its glucuronide conjugate constituted about 6% of the dose. In a 16-subject crossover bioavailability study, a linear relationship in the dose range of 2.5 to 10 mg was found between the dose of diphenoxylate hydrochloride (given as Lomotil liquid) and the peak plasma concentration, the area under the plasma concentration-time curve, and the amount of diphenoxylic acid excreted in the urine. In the same study the bioavailability of the tablet compared with an equal dose of the liquid was approximately 90%. The average peak plasma concentration of diphenoxylic acid following ingestion of four 2.5 mg tablets was 163 ng/ml at about 2 hours, and the elimination half-life of diphenoxylic acid was approximately 12 to 14 hours.
In dogs, diphenoxylate hydrochloride has a direct effect on circular smooth muscle of the bowel that conceivably results in segmentation and prolongation of gastrointestinal transit time. The clinical antidiarrheal action of diphenoxylate hydrochloride may thus be a consequence of enhanced segmentation that allows increased contact of the intraluminal contents with the intestinal mucosa.
Lomotil is indicated as adjunctive therapy in the management of diarrhea in patients 13 years of age and older.
Lomotil is contraindicated in:
Cases of severe respiratory depression and coma, leading to permanent brain damage or death have been reported in patients less than 6 years of age who received Lomotil. Lomotil is contraindicated in patients less than 6 years of age due to these risks (see CONTRAINDICATIONS).
Toxicities associated with the atropine and diphenoxylate components of Lomotil have been reported. The initial presenting symptoms may be delayed by up to 30 hours due to prolonged gastric emptying time induced by diphenoxylate hydrochloride. Clinical presentations vary in terms of which toxicity (anticholinergic vs. opioid) will present first or predominate; non-specific findings have been reported and include symptoms such as drowsiness (see OVERDOSAGE).
The use of Lomotil should be accompanied by appropriate fluid and electrolyte therapy, when indicated. If severe dehydration or electrolyte imbalance is present, Lomotil should be withheld until appropriate corrective therapy has been initiated. Drug-induced inhibition of peristalsis may result in fluid retention in the intestine, which may further aggravate dehydration and electrolyte imbalance.
Lomotil is contraindicated in patients with diarrhea associated with organisms that penetrate the GI mucosa (toxigenic E. coli, Salmonella, Shigella), and pseudomembranous enterocolitis (Clostridium difficile) associated with broad-spectrum antibiotics (see CONTRAINDICATIONS). Antiperistaltic agents, including Lomotil, slow gastrointestinal motility and may enhance bacterial overgrowth and the release of bacterial exotoxins. Lomotil has been reported to result in serious GI complications in patients with infectious diarrhea, including sepsis, prolonged and/or worsened diarrhea. Prolonged fever and the delay in the resolution of stool pathogens were reported in study of Shigellosis in adults who used Lomotil vs. placebo.
In some patients with acute ulcerative colitis, agents that inhibit intestinal motility or prolong intestinal transit time have been reported to induce toxic megacolon. Consequently, patients with acute ulcerative colitis should be carefully observed and Lomotil therapy should be discontinued promptly if abdominal distention occurs or if other untoward symptoms develop.
Since the chemical structure of diphenoxylate hydrochloride is similar to that of meperidine hydrochloride, the concurrent use of Lomotil with monoamine oxidase (MAO) inhibitors may, in theory, precipitate hypertensive crisis.
Lomotil should be used with extreme caution in patients with advanced hepatorenal disease and in all patients with abnormal liver function since hepatic coma may be precipitated.
Diphenoxylate hydrochloride may potentiate the action of other drugs that cause dizziness or drowsiness, including barbiturates, benzodiazepines and other sedatives/hypnotics, anxiolytics, and tranquilizers, muscle relaxants, general anesthetics, antipsychotics, other opioids, and alcohol. Therefore, the patient should be closely observed when any of these are used concomitantly.
Since a subtherapeutic dose of atropine has been added to Lomotil, consideration should be given to the development of adverse reactions associated with atropine (see WARNINGS). Lomotil has caused atropinism (hyperthermia, tachycardia, urinary retention, flushing, dryness of the skin and mucous membranes) particularly in pediatric patients with Down's syndrome. Lomotil is not indicated for use in pediatric patients (see CONTRAINDICATIONS and WARNINGS). Monitor patients for signs of atropinism.
Alcohol may increase the CNS depressant effects of Lomotil and may cause drowsiness (see WARNINGS). Avoid concomitant use of Lomotil with alcohol.
The concurrent use of Lomotil with other drugs that cause CNS depression (e.g., barbiturates, benzodiazepines, opioids, buspirone, antihistamines, muscle relaxants), may potentiate the effects of Lomotil (see WARNINGS). Either Lomotil or the other interacting drug should be chosen, depending on the importance of the drug to the patient. If CNS-acting drugs cannot be avoided, monitor patients for CNS adverse reactions.
No long-term study in animals has been performed to evaluate carcinogenic potential. Diphenoxylate hydrochloride was administered to male and female rats in their diets to provide dose levels of 4 and 20 mg/kg/day throughout a three-litter reproduction study. At 50 times the human dose (20 mg/kg/day), female weight gain was reduced and there was a marked effect on fertility as only 4 of 27 females became pregnant in three test breedings. The relevance of this finding to usage of Lomotil in humans is unknown.
Diphenoxylate hydrochloride has been shown to have an effect on fertility in rats when given in doses 50 times the human dose (see above discussion). Other findings in this study include a decrease in maternal weight gain of 30% at 20 mg/kg/day and of 10% at 4 mg/kg/day. At 10 times the human dose (4 mg/kg/day), average litter size was slightly reduced.
Teratology studies were conducted in rats, rabbits, and mice with diphenoxylate hydrochloride at oral doses of 0.4 to 20 mg/kg/day. Due to experimental design and small numbers of litters, embryotoxic, fetotoxic, or teratogenic effects cannot be adequately assessed. However, examination of the available fetuses did not reveal any indication of teratogenicity.
There are no adequate and well-controlled studies in pregnant women. Lomotil should be used during pregnancy only if the anticipated benefit justifies the potential risk to the fetus.
Caution should be exercised when Lomotil is administered to a nursing woman, since the physicochemical characteristics of the major metabolite, diphenoxylic acid, are such that it may be excreted in breast milk and since it is known that atropine is excreted in breast milk.
The safety and effectiveness of Lomotil have been established in pediatric patients 13 years of age and older as adjunctive therapy in the management of diarrhea. The safety and effectiveness of Lomotil have not been established in pediatric patients less than 13 years of age.
Lomotil is contraindicated in pediatric patients less than 6 years of age due to the risks of severe respiratory depression and coma, possibly resulting in permanent brain damage or death (see CONTRAINDICATIONS).
Lomotil has caused atropinism, particularly in pediatric patients with Down's syndrome (see PRECAUTIONS).
In case of accidental ingestion of Lomotil by pediatric patients, see OVERDOSAGE for recommended treatment.
The following serious adverse reactions are described elsewhere in labeling:
At therapeutic doses of Lomotil, the following other adverse reactions have been reported; they are listed in decreasing order of severity, but not of frequency:
Nervous system: numbness of extremities, euphoria, depression, malaise/lethargy, confusion, sedation/drowsiness, dizziness, restlessness, headache, hallucination
Allergic: anaphylaxis, angioneurotic edema, urticaria, swelling of the gums, pruritus
Gastrointestinal system: megacolon, paralytic ileus, pancreatitis, vomiting, nausea, anorexia, abdominal discomfort
The following adverse reactions related to atropine sulfate are listed in decreasing order of severity, but not of frequency: hyperthermia, tachycardia, urinary retention, flushing, dryness of the skin and mucous membranes.
Lomotil is classified as a Schedule V controlled substance by federal regulation. Diphenoxylate hydrochloride is chemically related to the narcotic analgesic meperidine.
In doses used for the treatment of diarrhea, whether acute or chronic, diphenoxylate has not produced addiction.
Diphenoxylate hydrochloride is devoid of morphine-like subjective effects at therapeutic doses. At high doses it exhibits codeine-like subjective effects. The dose which produces antidiarrheal action is widely separated from the dose which causes central nervous system effects. The insolubility of diphenoxylate hydrochloride in commonly available aqueous media precludes intravenous self-administration. A dose of 100 to 300 mg/day, which is equivalent to 40 to 120 tablets, administered to humans for 40 to 70 days, produced opiate withdrawal symptoms. Since addiction to diphenoxylate hydrochloride is possible at high doses, the recommended dosage should not be exceeded.
Overdosage can be life-threatening. Symptoms of overdosage may include opioid and/or anticholinergic effects including respiratory depression, coma, delirium, lethargy, dryness of the skin and mucous membranes, mydriasis or miosis, flushing, hyperthermia, tachycardia, hypotonia, tachypnea, toxic encephalopathy, seizures and incoherent speech.
Respiratory depression has been reported up to 30 hours after ingestion and may recur despite an initial response to narcotic antagonists.
Treat all possible Lomotil overdosages as serious and maintain medical observation/hospitalization until patients become asymptomatic without naloxone use.
A pure narcotic antagonist (e.g., naloxone) should be used in the treatment of respiratory depression caused by Lomotil. Refer to the prescribing information for naloxone. Consider Lomotil toxicity even in settings of negative toxicology tests.
Following initial improvement of respiratory function, repeated doses of naloxone hydrochloride may be required to counteract recurrent respiratory depression.
If over-exposure occurs, call your Poison Control Center at 1-800-222-1222 for current information on the management of poisoning or overdosage.
Lomotil is recommended as adjunctive therapy for the management of diarrhea in patients 13 years of age and older. Consider the nutritional status and degree of dehydration in patients prior to initiating therapy with Lomotil. The use of Lomotil should be accompanied by appropriate fluid and electrolyte therapy, when indicated. If severe dehydration or electrolyte imbalance is present, do not administer Lomotil until appropriate corrective therapy has been indicated (see WARNINGS).
The initial adult dosage is 2 Lomotil tablets four times daily (maximum total daily dose of 20 mg per day of diphenoxylate hydrochloride). Most patients will require this dosage until initial control of diarrhea has been achieved. Clinical improvement of acute diarrhea is usually observed within 48 hours.
After initial control has been achieved, the Lomotil dosage may be reduced to meet individual requirements. Control may often be maintained with as little as two Lomotil tablets daily.
Tablets — round, white, with SEARLE debossed on one side and 61 on the other side and containing 2.5 mg of diphenoxylate hydrochloride and 0.025 mg of atropine sulfate, supplied as:
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