Loperamide Hydrochloride

LOPERAMIDE HYDROCHLORIDE — loperamide hydrochloride capsule
State of Florida DOH Central Pharmacy

DESCRIPTION

Loperamide hydrochloride is a white to slightly yellow powder and is freely soluble in methanol, isopropyl alcohol, chloroform and slightly soluble in water.

Loperamide hydrochloride, 4-(p-chlorophenyl)-4-hydroxy-N,N-dimethyl-α,α-diphenyl-1-piperidinebutyramide monohydrochloride, is a synthetic antidiarrheal for oral use. Its structural formula is:

Structural Formula

C29 H33 ClN2 O2 .HCl M.W. 513.51

Loperamide hydrochloride is available in 2 mg capsules.

Each capsule, for oral administration, contains 2 mg loperamide hydrochloride. Loperamide hydrochloride capsules USP also contain the inactive ingredients: pregelatinized corn starch, gelatin capsules, iron oxides, lactose monohydrate, magnesium stearate, and titanium dioxide.

CLINICAL PHARMACOLOGY

In vitro and animal studies show that loperamide hydrochloride acts by slowing intestinal motility and by affecting water and electrolyte movement through the bowel. Loperamide binds to the opiate receptor in the gut wall. Consequently, it inhibits the release of acetylcholine and prostaglandins, thereby reducing peristalsis, and increasing intestinal transit time. Loperamide increases the tone of the anal sphincter, thereby reducing incontinence and urgency.

In man, loperamide hydrochloride prolongs the transit time of the intestinal contents. It reduces the daily fecal volume, increases the viscosity and bulk density, and diminishes the loss of fluid and electrolytes. Tolerance to the antidiarrheal effect has not been observed. Clinical studies have indicated that the apparent elimination half-life of loperamide hydrochloride in man is 10.8 hours with a range of 9.1 to 14.4 hours. Plasma levels of unchanged drug remain below 2 nanograms per mL after the intake of a 2 mg loperamide hydrochloride capsule. Plasma levels are highest approximately five hours after administration of the capsule and 2.5 hours after the liquid. The peak plasma levels of loperamide were similar for both formulations. Elimination of loperamide mainly occurs by oxidative N-demethylation. Cytochrome P450 (CYP450) isozymes, CYP2C8 and CYP3A4, are thought to play an important role in loperamide N-demethylation process since quercetin (CYP2C8 inhibitor) and ketoconazole (CYP3A4 inhibitor) significantly inhibited the N-demethylation process in vitro by 40% and 90%, respectively. In addition, CYP2B6 and CYP2D6 appear to play a minor role in loperamide N-demethylation. Excretion of the unchanged loperamide and its metabolites mainly occurs through the feces. In those patients in whom biochemical and hematological parameters were monitored during clinical trials, no trends toward abnormality during loperamide hydrochloride therapy were noted. Similarly, urinalyses, EKG and clinical ophthalmological examinations did not show trends toward abnormality.

INDICATIONS AND USAGE

Loperamide hydrochloride capsules are indicated for the control and symptomatic relief of acute nonspecific diarrhea and of chronic diarrhea associated with inflammatory bowel disease. Loperamide hydrochloride capsules are also indicated for reducing the volume of discharge from ileostomies.

CONTRAINDICATIONS

Loperamide hydrochloride capsules are contraindicated in patients with known hypersensitivity to loperamide hydrochloride or to any of the excipients.

Loperamide hydrochloride is contraindicated in patients with abdominal pain in the absence of diarrhea.

Loperamide hydrochloride is not recommended in infants below 24 months of age.

Loperamide hydrochloride should not be used as the primary therapy:

  • in patients with acute dysentery, which is characterized by blood in stools and high fever,
  • in patients with acute ulcerative colitis,
  • in patients with bacterial enterocolitis caused by invasive organisms including Salmonella, Shigella, and Campylobacter,
  • in patients with pseudomembranous colitis associated with the use of broad-spectrum antibiotics.

WARNINGS

Fluid and electrolyte depletion often occur in patients who have diarrhea. In such cases, administration of appropriate fluid and electrolytes is very important. The use of loperamide hydrochloride does not preclude the need for appropriate fluid and electrolyte therapy.

In general, loperamide hydrochloride should not be used when inhibition of peristalsis is to be avoided due to the possible risk of significant sequelae including ileus, megacolon and toxic megacolon. Loperamide hydrochloride must be discontinued promptly when constipation, abdominal distention or ileus develop.

Treatment of diarrhea with loperamide hydrochloride is only symptomatic. Whenever an underlying etiology can be determined, specific treatment should be given when appropriate (or when indicated).

Patients with AIDS treated with loperamide hydrochloride for diarrhea should have therapy stopped at the earliest signs of abdominal distention. There have been isolated reports of toxic megacolon in AIDS patients with infectious colitis from both viral and bacterial pathogens treated with loperamide hydrochloride. {ref EDMS-PSDB-2564186, p. 12}

Loperamide hydrochloride should be used with special caution in young children because of the greater variability of response in this age group. Dehydration, particularly in younger children, may further influence the variability of response to loperamide hydrochloride.

PRECAUTIONS

General

Extremely rare allergic reactions including anaphylaxis and anaphylactic shock have been reported. In acute diarrhea, if clinical improvement is not observed in 48 hours, the administration of loperamide hydrochloride should be discontinued and patients should be advised to consult their physician. Although no pharmacokinetic data are available in patients with hepatic impairment, loperamide hydrochloride should be used with caution in such patients because of reduced first pass metabolism. Patients with hepatic dysfunction should be monitored closely for signs of CNS toxicity. No pharmacokinetic data are available in patients with renal impairment. Since it has been reported that the majority of the drug is metabolized and metabolites or the unchanged drug is excreted mainly in the feces, dosage adjustments in patients with renal impairment are not required. No formal studies have been conducted to evaluate the pharmacokinetics of loperamide in elderly subjects. However, in two studies that enrolled elderly patients, there were no major differences in the drug disposition in elderly patients with diarrhea relative to young patients.

Information for Patients

Patients should be advised to check with their physician if their diarrhea does not improve in 48 hours or if they note blood in their stools, develop a fever or develop abdominal distention.

Tiredness, dizziness, or drowsiness may occur in the setting of diarrheal syndromes treated with loperamide hydrochloride. Therefore, it is advisable to use caution when driving a car or operating machinery. (See ADVERSE REACTIONS).

Drug Interactions

Nonclinical data have shown that loperamide is a P-glycoprotein substrate. Concomitant administration of loperamide (16 mg single dose) with a 600 mg single dose of either quinidine or ritonavir, both of which are P-glycoprotein inhibitors, resulted in a 2 to 3 fold increase in loperamide plasma levels. Due to the potential for enhanced central effects when loperamide is coadministered with quinidine and with ritonavir, caution should be exercised when loperamide is administered at the recommended dosages (2 mg, up to 16 mg maximum daily dose) with P-glycoprotein inhibitors.

When a single 16 mg dose of loperamide is coadministered with a 600 mg single dose of saquinavir, loperamide decreased saquinavir exposure by 54%, which may be of clinical relevance due to reduction of therapeutic efficacy of saquinavir. The effect of saquinavir on loperamide is of less clinical significance. Therefore, when loperamide is given with saquinavir, the therapeutic efficacy of saquinavir should be closely monitored.

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