Atropine/ diphenoxylate( Lomotil® )
Each Lomotil tablet and each 5 ml of Lomotil liquid for oral use contains :
diphenoxylate hydrochloride 2.5 mg
atropine sulfate 0.025 mg
Atropine/diphenoxylate is an antidiarrheal and anticholinergic combination. It works by decreasing the motion of muscles in the intestines and prolonging the time it takes to move the contents through the body.
Mechanism of effect
Diphenoxylate : Acts on smooth muscle of intestinal tract, inhibiting GI motility and excessive GI propulsion (like morphine)
Atropine : Subtherapeutic quantity of atropine is added to discourage deliberate overdose of diphenoxylate
Pharmacodynamic
Diphenoxylate, an antidiarrheal, is effective as adjunctive therapy in the management of diarrhea. 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.
Pharmacokinetics
Absorption :
Onset: 45 min-1 hr
Duration: 3-4 hr
Peak plasma time: 2 hr
Bioavailability: 90%
Distribution : Vd: 324.2 L
Metabolism : Extensively metabolized in liver to active metabolite, diphenoxylic acid (difenoxin), which is 5 times more potent than diphenoxylate
Metabolites : Diphenoxylic acid (active), hydroxydiphenoxylic acid (inactive)
Elimination : Half-life: 2.5 hr (diphenoxylate); 3-14 hr (diphenoxylic acid)
Renal clearance : 1483 mL/min
Excretion : Fecesvia bile (49%), urine (14%)
Dosage
Usual Adult Dose for Diarrhea
5 mg diphenoxylate/0.05 mg atropine(2 tablets or 10 ml) PO q6hr; not to exceed 20 mg diphenoxylate daily
Maintenance : As low as ¼ of initial dosage
Usual Pediatric Dose for Diarrhea
2 years and older :
Initial dose: 0.3 to 0.4 mg/kg of diphenoxylate, PO q6hr; not to exceed 20 mg diphenoxylate daily
Drug contraindications
bowel obstruction , blockage of the urinary tract , Myasthenia gravis , angle-closure glaucoma , Hypersensitivity to this drug , blockage of the stomachSide effects
nausea , dry mouth , Blurred vision , dry skin , pancreatitis , difficulty urinating , Abdominal discomfortInteractions
Amitriptyline , Imipramine , Phenobarbital , Sodium Oxybate , Phenelzine , BenzatropineAlerts
• Atropine/diphenoxylate may cause drowsiness, dizziness, or blurred vision. These effects may be worse if you take it with alcohol or certain medicines. Use atropine/diphenoxylate with caution. Do not drive or perform other possibly unsafe tasks until you know how you react to it.
• Lomotil Improvement of symptoms expected within 48 hours; if no improvement within this time, drug is unlikely to be effective .
• 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 and in patients with Ulcerative colitis.
• Diphenoxylate hydrochloride may potentiate the action of barbiturates, tranquilizers, and alcohol. Therefore, the patient should be closely observed when any of these are used concomitantly.
• Use atropine/diphenoxylate with caution in the ELDERLY; they may be more sensitive to its effects, especially excitement, agitation, or drowsiness.
• Atropine/diphenoxylate should not be used in CHILDREN younger than 13 years old; safety and effectiveness in these children have not been confirmed.
• Atropine/diphenoxylate may make your eyes more sensitive to sunlight. It may help to wear sunglasses.
Points of recommendation
• Take atropine/diphenoxylate by mouth with or without food.
• Do not drink alcohol or use medicines that may cause drowsiness (eg, sleep aids, muscle relaxers) while you are using atropine/diphenoxylate; it may add to their effects. Ask your pharmacist if you have questions about which medicines may cause drowsiness.
• Do not become overheated in hot weather or while you are being active; heatstroke may occur.
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