Diethylpropion Hydrochloride

DIETHYLPROPION HYDROCHLORIDE- diethylpropion hydrochloride tablet, extended release
DIETHYLPROPION HYDROCHLORIDE- diethylpropion hydrochloride tablet
H.J. Harkins Company, Inc.

Cliniccal Pharmacology Section

Diethylpropion hydrochloride is a sympathomimetic amine with some pharmacologic activity similar to that of the prototype drugs of this class used in obesity, the amphetamines. Actions include some central nervous system stimulation and elevation of blood pressure. Tolerance has been demonstrated with all drugs of this class in which these phenomena have been looked for.

Drugs of this class used in obesity are commonly known as “anorectics” or “anorexigenics.” It has not been established, however, that the action of such drugs in treating obesity is primarily one of appetite suppression. For example, other central nervous system actions or metabolic effects may be involved.

Adult obese subjects instructed in dietary management and treated with “anorectic” drugs lose more weight on the average than those treated with placebo and diet, as determined in relatively short-term clinical trials.

The magnitude of increased weight loss of drug-treated patients over placebo-treated patients averages some fraction of a pound a week. However, individual weight loss may vary substantially from patient to patient. The rate of weight loss is greatest in the first weeks of therapy for both drug and placebo subjects and tends to decrease in succeeding weeks. The possible origins of the increased weight loss due to the various drug effects are not established. The amount of weight loss associated with the use of an “anorectic” drug varies from trial to trial, and the increased weight loss appears to be related in part to variables other than the drug prescribed, such as the physician/investigator relationship, the population treated, and the diet prescribed. Studies do not permit conclusions as to the relative importance of the drug and non-drug factors on weight loss.

The natural history of obesity is measured in years, whereas most studies cited are restricted to a few weeks duration; thus, the total impact of drug-induced weight loss over that of diet alone is unknown.

Diethylpropion is rapidly absorbed from the GI tract after oral administration and is extensively metabolized through a complex pathway of biotransformation involving N-dealkylation and reduction. Many of these metabolites are biologically active and may participate in the therapeutic action of diethylpropion hydrochloride extended release tablets, 75 mg. Due to the varying lipid solubilities of these metabolites, their circulating levels are affected by urinary pH. Diethylpropion and/or its active metabolites are believed to cross the blood-brain barrier and the placenta.

Diethylpropion and its metabolites are excreted mainly by the kidney. It has been reported that between 75-106% of the dose is recovered in the urine within 48 hours after dosing. Using a phosphorescence assay that is specific for basic compounds containing benzoyl group, the plasma half-life of the aminoketone metabolites is estimated to be between 4 to 6 hours.

The controlled-release characteristics of diethylpropion hydrochloride extended release tablets, 75 mg have been demonstrated by studies in humans in which plasma levels of diethylpropion-related materials were measured by phosphorescence analysis. Plasma levels obtained with the diethylpropion hydrochloride extended release tablets, 75 mg formulation administered once daily indicated a more gradual release than the immediate-release formulation (three 25 mg tablets given in a single dose).

Diethylpropion hydrochloride extended release tablets, 75 mg have not been shown superior in effectiveness to the same dosage of the immediate-release formulation (one 25 mg tablet three times daily). After administration of a single dose of diethylpropion hydrochloride extended release tablets, 75 mg (one 75 mg extended release tablet) or diethylpropion hydrochloride solution (75 mg dose) in a cross-over study using normal human subjects, the amount of parent compound and its active metabolites recovered in the urine within 48 hours for the two dosage forms were not statistically different.

Description

Release Tablets, 75 mg are available for oral administration as extended release tablets containing 75 mg diethylpropion hydrochloride, USP. The inactive ingredients in each extended release tablet are: mannitol, carbomer homopolymer, tartaric acid, hydroxypropyl methylcellulose, povidone, and magnesium stearate.

Diethylpropion hydrochloride is a sympathomimetic agent. The chemical name for diethylpropion hydrochloride is 1-phenyl-2-diethyl-amino-1-propanone hydrochloride.

Its chemical structure is:

In diethylpropion hydrochloride extended release tablets, 75 mg, diethylpropion hydrochloride is dispersed in a hydrophilic matrix. On exposure to water, the diethylpropion hydrochloride is released at a relatively uniform rate as a result of slow hydration of the matrix. The result is controlled release of the anorectic agent.

Indincations and Usage

Diethylpropion hydrochloride extended release tablets, 75 mg are indicated in the management of exogenous obesity as a short-term adjunct (a few weeks) in a regimen of weight reduction based on caloric restriction in patients with an initial body mass index (BMI) of 30 kg/m2 or higher and who have not responded to appropriate weight reducing regimen (diet and/or exercise) alone. Below is a chart of BMI based on various heights and weights. BMI is calculated by taking the patient’s weight, in kilograms (kg), divided by the patient’s height, in meters (m), squared. Metric conversions are as follows: pounds divided by 2.2 = kg; inches x 0.0254 = meters.

Body Mass Index (BMI), kg/m2
Weight Height (feet, inches)
(pounds)
5’0” 5’3” 5’6” 5’9” 6’0” 6’3”
140 27 25 23 21 19 18
150 29 27 24 22 20 19
160 31 28 26 24 22 20
170 33 30 28 25 23 21
180 35 32 29 27 25 23
190 37 34 31 28 26 24
200 39 36 32 30 27 25
210 41 37 34 31 29 26
220 43 39 36 33 30 28
230 45 41 37 34 31 29
240 47 43 39 36 33 30
250 49 44 40 37 34 31

The usefulness of agents of this class (see CLINICAL PHARMACOLOGY) should be measured against possible risk factors inherent in their use such as those described below. Diethylpropion hydrochloride extended release tablets, 75 mg are indicated for use as monotherapy only.

Contraindications

Pulmonary hypertension, advanced arteriosclerosis, hyperthyroidism, known hypersensitivity or idiosyncrasy to the sympathomimetic amines, glaucoma, severe hypertension. (See PRECAUTIONS).

Agitated states.

Patients with a history of drug abuse.

Use in combination with other anorectic agents is contraindicated.

During or within 14 days following the administration of monoamine oxidase inhibitors, hypertensive crises may result.

Warnings

Diethylpropion hydrochloride extended release tablets, 75 mg should not be used in combination with other anorectic agents, including prescribed drugs, over-the-counter preparations, and herbal products.

In a case-control epidemiological study, the use of anorectic agents, including diethylpropion, was associated with an increased risk of developing pulmonary hypertension, a rare, but often fatal disorder. The use of anorectic agents for longer than 3 months was associated with a 23-fold increase in the risk of developing pulmonary hypertension. Increased risk of pulmonary hypertension with repeated courses of therapy cannot be excluded.

The onset or aggravation of exertional dyspnea, or unexplained symptoms of angina pectoris, syncope, or lower extremity edema suggest the possibility of occurrence of pulmonary hypertension. Under these circumstances, diethylpropion hydrochloride extended release tablets, 75 mg should be immediately discontinued, and the patient should be evaluated for the possible presence of pulmonary hypertension.

Valvular heart disease associated with the use of some anorectic agents such as fenfluramine and dexfenfluramine has been reported. Possible contributing factors include use for extended periods of time, higher than recommended dose, and/or use in combination with other anorectic drugs. Valvulopathy has been very rarely reported with diethylpropion hydrochloride extended release tablets, 75 mg monotherapy, but the causal relationship remains uncertain. The potential risk of possible serious adverse effects such as valvular heart disease and pulmonary hypertension should be assessed carefully against the potential benefit of weight loss. Baseline cardiac evaluation should be considered to detect preexisting valvular heart diseases or pulmonary hypertension prior to initiation of diethylpropion hydrochloride extended release tablets, 75 mg treatment. Diethylpropion hydrochloride extended release tablets, 75 mg are not recommended in patients with known heart murmur or valvular heart disease. Echocardiogram during and after treatment could be useful for detecting any valvular disorders which may occur.

To limit unwarranted exposure and risks, treatment with diethylpropion hydrochloride extended release tablets, 75 mg should be continued only if the patient has satisfactory weight loss within the first 4 weeks of treatment (e.g., weight loss of at least 4 pounds, or as determined by the physician and patient).

Diethylpropion hydrochloride extended release tablets, 75 mg are not recommended for patients who used any anorectic agents within the prior year.

If tolerance develops, the recommended dose should not be exceeded in an attempt to increase the effect; rather, the drug should be discontinued. Diethylpropion hydrochloride extended release tablets, 75 mg may impair the ability of the patient to engage in potentially hazardous activities such as operating machinery or driving a motor vehicle; the patient should therefore be cautioned accordingly.

Prolonged use of diethylpropion hydrochloride may induce dependence with withdrawal syndrome on cessation of therapy. Hallucinations have occurred rarely following high doses of the drug. Several cases of toxic psychosis have been reported following the excessive use of the drug and some have been reported in which the recommended dose appears not to have been exceeded. Psychosis abated after the drug was discontinued. When central nervous system active agents are used, consideration must always be given to the possibility of adverse interactions with alcohol.