DESCRIPTION
Phentermine hydrochloride is a sympathomimetic amine anorectic. Its chemical name is α,α,-dimethylphenethylamine hydrochloride. The structural formula is as follows:
Chemical structure-figure-02
Phentermine hydrochloride is a white, odorless, hygroscopic, crystalline powder which is soluble in water and lower alcohols, slightly soluble in chloroform and insoluble in ether.
LOMAIRA™ tablet is available as an oral tablet containing 8 mg of phentermine hydrochloride (equivalent to 6.4 mg of phentermine base). Each LOMAIRA™ tablet also contains the following inactive ingredients: Corn Starch, Magnesium Stearate, NF, Microcrystalline Cellulose 102, NF, Stearic Acid, NF, FD&C Blue #1, Sucrose and Pharmaceutical Glaze.
CLINICAL PHARMACOLOGY
Mechanism of Action
Phentermine is a sympathomimetic amine with pharmacologic activity similar to the prototype drugs of this class used in obesity, amphetamine (d- and dll-amphetamine). Drugs of this class used in obesity are commonly known as “anorectics” or “anorexigenics.” It has not been established that the primary action of such drugs in treating obesity is one of appetite suppression since other central nervous system actions, or metabolic effects, may also be involved.
Pharmacodynamics
Typical actions of amphetamines include central nervous system stimulation and elevation of blood pressure. Tachyphylaxis and tolerance have been demonstrated with all drugs of this class in which these phenomena have been looked for.
Pharmacokinetics
Specific Populations
Renal Impairment
Phentermine was not studied in patients with renal impairment. The literature reported cumulative urinary excretion of phentermine under uncontrolled urinary pH conditions is 62%-85%. Exposure increases can be expected in patients with renal impairment. Use caution when administering phentermine to patients with renal impairment.
CLINICAL STUDIES
In relatively short-term clinical trials, adult obese subjects instructed in dietary management and treated with “anorectic” drugs lost more weight on the average than those treated with placebo and diet.
The magnitude of increased weight loss of drug-treated patients over placebo-treated patients is only a fraction of a pound a week. 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 drugs prescribed, such as the physician-investigator, 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 over several years, whereas the studies cited are restricted to a few weeks’ duration; thus, the total impact of drug-induced weight loss over that of diet alone must be considered clinically limited.
INDICATIONS AND USAGE
LOMAIRA™ tablets are indicated as a short-term (a few weeks) adjunct in a regimen of weight reduction based on exercise, behavioral modification and caloric restriction in the management of exogenous obesity in patie |
