Encyclopedia of Diets - A Guide to Health and Nutrition

Precautions

Phentermine hydrochloride tablets and capsules
are indicated only as short-term monotherapy for the
management of exogenous obesity. The safety and
efficacy of combination therapy with phentermine
and any other drug products for weight loss, including
selective serotonin reuptake inhibitors (eg, fluoxetine,
sertraline, fluvoxamine, paroxetine), have not been
established. Therefore, coadministration of these
drug products for weight loss is not recommended.

Serious regurgitant cardiac valvular disease, pri-
marily affecting the mitral, aortic and tricuspid valves,
has been reported in otherwise healthy persons who
had taken a combination of phentermine with fenflur-
amine or dexfenfluramine for weight loss. The etiology
of these valvulopathies has not been established and
their course in individuals after the drugs are stopped
is not known. The possibility of an association
between valvular heart disease and the use of phenter-
mine alone cannot be ruled out; there have been rare
cases of valvular heart disease in patients who report-
edly have taken phentermine alone.

Tolerance to the anorectic effect usually develops
within a few weeks. When this occurs, the recommended
dose should not be exceeded in an attempt to increase the
effect; rather, the drug should be discontinued.

Interactions

Phentermine hydrochloride may decrease the
hypotensive effect of guanethidine.

Mono-amine oxidase inhibitors (MAOIs) may
increase the pressor response to the anorexiants. Possi-
ble hypertensive crisis and intracranial hemorrhage
may occur. This interaction may also occur with fura-
zolidone, an antimicrobial with MAOI activity. Avoid
combining with phentermine hydrochloride. There
should be a 14 day interval between use of any MAOI
and phentermine.

Aftercare

For those patients who had been exposed to fen-
fluramine, aftercare depends on the extent of damage.
For those patients with significant heart valve dam-
age, surgical valve replacement may be in order. Those
who received the drug but show no damage should be
monitored by a cardiologist for the possibility of late
onset damage.

Although phentermine alone has been associated
with rare instances of valvular heart disease, there are
no recommendations for routine aftercare or monitoring.

Parental concerns

Phentermine is not indicated for patients under

the age of 16 years.

Resources

BOOKS

Reynolds JEF, Prasad ABMartindale The Extra Pharma-

copoeia 28th edition, The Pharmaceutical Press,

London 1982

PERIODICALS

Kannengiesser MH, Hunt PE, Raynaud JP

Weintraub M, Sundaresan PR, et al. Long-term weight

control study. II (weeks 34 to 104). An open-label

study of continuous fenfluramine plus phentermine

versus targeted intermittent medication as adjuncts

to behavior modification, caloric restriction, and

exercise.Clin Pharmacol Ther. 1992

May;51(5):595-601

Weintraub M, Sundaresan PR, et alLong-term weight

control study. II (weeks 34 to 104). An open-label

study of continuous fenfluramine plus phentermine

versus targeted intermittent medication as adjuncts

to behavior modification, caloric restriction, and

exercise. Clin. Pharmacol Ther 1992

May;51(5):595-601

Weintraub M, Sundaresan PR, et alLong-term weight con-

trol study V (weeks 190 to 210). Follow-up of partic-

ipants after cessation of medication. Clin. Pharmacol

Ther 1992 May;51(5):615-8

Connolly HM, Crary JL, McGoon MD, et al.Valvular heart

disease associated with fenfluraminephentermine. N

Engl J Med 1997;337:581 8.

OTHER

http://www.phentermine.com

http://www.rxlist.com/script/main/art.asp?articlekey=76791

http://www.fda.gov/cder/news/mmwr.pdf

http://biotech.law.lsu.edu/cases/drugs/brown_v_AHPC

.htm

ORGANIZATIONS

American Obesity Association. 1250 24th Street, NW, Suite

300, Washington, DC 20037. 800-98-OBESE (800-986-

2373).

Food and Drug Administration. U.S. Department of Health

and Human Services, Public Health Service, 5600

Fishers Lane, Rockville, MD 20857.

Weight-control Information Network (WIN). National

Institute of Diabetes and Digestive and Kidney Dis-

eases. 1 Win Way, Bethesda, MD 20892-3665. 877-946-

4627. 202-828-1025.

Sam Uretsky, PharmD

Fen-Phen