Phenmetrazine (Filon, Preludin)
Pronunciation: fen-MET-rah-zeen
Chemical Abstracts Service Registry Number: 134-49-6
Formal Names: Filon, Preludin
Informal Names: Sweeties
Type: Stimulant (anorectic class).
Federal Schedule Listing: Schedule II (DEA no. 1631)
USA Availability: Prescription
Uses.
Immediately upon announcement of the drug’s discovery in 1954 it was utilized in Germany as an appetite suppressant. A couple years later the same medical use began in the United States with expansive claims about patients obtaining substantial weight loss without having to follow a regimen of dieting, claims that became more modest as experience with the drug spread. One experiment testing the drug’s influence on appetite yielded a result relevant to drug experiments in general: The substance worked better when people knew its intended effect. If people knew they were supposed to feel less hungry, they noticed less desire for food and then ate less. Early reports praised phenmetrazine for producing more appetite loss than amphetamine and with fewer unwanted effects. Since then phenmetrazine has fallen into disfavor due to concern about addictive potential even though the drug is described as resembling caffeine more than amphetamine.
In dogs phenmetrazine has only one sixth to one tenth the strength of amphetamine. One type of canine experiment showed dextroamphetamine to be 250 times stronger than phenmetrazine. In dogs a much higher dose of phenmetrazine is needed for the same weight loss produced by benzphetamine, and an experiment with 75 humans had results consistent with that tendency,
finding phenmetrazine to be less effective than benzphetamine in promoting weight loss. In contrast, another human weight reduction experiment with 81 persons was unable to demonstrate such a difference. That study did show, however, that users obtain fewer amphetamine effects from phenmetrazine than from dextroamphetamine.
Phenmetrazine has worked as an antidepressant, and for some overweight persons that effect may enhance the drug’s appeal (overeating can be a response to depression). The substance shows effectiveness against motion sickness and against symptoms of diabetes insipidus. As a possible cure for bedwetting, the drug produced mixed results. The compound has also been
used to treat asthma and Parkinson’s disease.
Drawbacks.
Intravenous abuse can harm muscles and kidneys. Phenmetrazine can produce standard amphetamine effects such as euphoria, restlessness, jumpiness, insomnia, tics, fatigue reduction, faster breathing, and higher blood pressure. Studies have found phenmetrazine’s actions on patients with heart trouble or hypertension (high blood pressure) to be measurable but negligible.
Taking the high blood pressure medicine propranolol along with phenmetrazine can relieve cardiac effects without diminishing anorectic effects. Studies with diabetic users find phenmetrazine having little influence on blood sugar levels or on insulin needs.
Fluctuating emotions and even psychosis have been attributed to phenmetrazine abuse. Psychosis can include hallucinations and paranoia. That affliction can stop when drug taking stops, or instead the drug may break down barriers releasing full-fledged and long-lasting schizophrenia. Phenmetrazine interferes with dreaming during sleep, which in itself may cause psychological trouble.
Abuse factors.
Tests of drug preference, in which users could choose among several substances, found benzphetamine and phenmetrazine to have about the same amount of appeal even though benzphetamine is a Schedule III substance (a status implying a lower addictive potential than phenmetrazine). In one such test, volunteers found phenmetrazine to be a satisfying substitute
for dextroamphetamine but preferred the latter. Abusers of amphetamine and methamphetamine have routinely switched to phenmetrazine when their favored drug was unavailable.
Drug interactions.
An experiment found that chlorpromazine (Thorazine) interacts with phenmetrazine, hindering phenmetrazine’s normal anorectic benefit.
Cancer.
In pregnant women phenmetrazine may undergo transformations suspected of promoting childhood tumors.
Pregnancy.
Phenmetrazine was formerly prescribed to pregnant women seeking to lose weight. A study of over 10,000 birth and childhood records found the drug having no “severe” impact on fetal development. Other studies have found no birth defects at all, although medical literature from the early 1960s does contain a handful of reports in which the drug is suspected of harming fetuses. Those suspicions were never verified but were strong enough to suspend medical use of the drug in some countries for a while.
Combination products.
Filon combines phenmetrazine theoclate (CAS RN 13931-75-4) and phenbutrazate hydrochloride and is promoted as having phenmetrazine’s weight loss characteristics while lacking hazard of addiction. Initial clinical trials showed Filon to be an effective anorectic with fewer of phenmetrazine’s unwanted qualities, but a later study found the two drugs
to have the same unwanted effects. A case of Filon addiction also surfaced, but that single instance hardly proves Filon to have more addictive potential than any other drug considered to have low or zero potential.
Additional scientific information may be found in:
Gilstrap, L.C. III, and B.B. Little, eds. Drugs and Pregnancy. New York: Elsevier, 1992.
Martin, W.R., et al. “Physiologic, Subjective, and Behavioral Effects of Amphetamine, Methamphetamine, Ephedrine, Phenmetrazine, and Methylphenidate in Man.”
Clinical Pharmacology and Therapeutics 12 (1971): 245–58.
Mellar, J., and L.E. Hollister. “Phenmetrazine: An Obsolete Problem Drug.” Clinical
Pharmacology and Therapeutics 32 (1982): 671–75.
Negulici, E., and D. Christodorescu. “Phenmetrazine Psychosis.” British Medical Journal
3 (1968): 316.
Penick, S.B, and J.R. Hinklele. “The Effect of Expectation on Response to Phenmetrazine.”
Psychosomatic Medicine 26 (1964): 369–73.
Rosen, A., and I.J. Oberman. “Addiction to Phenmetrazine Hydrochloride and Its Psychiatric
Implications.” Journal of the American Osteopathic Association 59 (1960): 722–26.
Spillane, J.P. “The Use of Phenmetrazine.” The Practitioner 185 (1960): 102–6.
Incoming search terms for the article:
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Pronunciation: fen-di-MEH-tra-zeen (also pronounced fen-dye-MEH-trah-zeen)
Chemical Abstracts Service Registry Number: 21784-30-5 (Bontril format); 569-59-5 (Plegine format); 50-58-8 (Prelu-2 format).
Formal Names: Bontril, Plegine, Prelu-2
Informal Names: Pink Hearts
Type: Stimulant (anorectic class).
Federal Schedule Listing: Schedule III (DEA no. 1615)
USA Availability: Prescription
Pregnancy Category: C
Uses.
Phendimetrazine is related to phenmetrazine. Indeed, the body converts part of a phendimetrazine dose into phenmetrazine, a fact to be remembered if employment drug screening unjustly accuses someone of using phenmetrazine. Short-term weight control is the main medical use of phendimetrazine; one experiment found it 20 more times effective than placebo— an astonishing result for any diet pill. Effectiveness declines as administration
continues, and standard practice is then to stop the drug gradually rather than increase the dosage. A derivative of the drug has been found useful for treating pyoderma gangrenosum, a skin affliction involving large sores.
Drawbacks.
If dosage suddenly stops, weariness and depression can occur. A small reduction in blood pressure is observed among some users, but generally the drug raises blood pressure and is considered inappropriate for persons with hypertension (high blood pressure). The compound has been linked with hypertension in blood circulation to lungs, a potentially fatal condition
causing trouble in breathing. Users have experienced edginess, disturbed sleep, headache, dizziness, lightheadedness, accelerated pulse rate, and feelings of heart tremors. Other muscle tremors can occur. Phendimetrazine can interfere with functioning needed to handle a car or dangerous tools. The compound can dry and even inflame the mouth, upset the stomach, loosen or tighten the bowels, and make urination frequent and painful. Persons should avoid the drug if they suffer from restlessness, glaucoma, excessive thyroid activity, heart disease, hardening of the arteries, or drug abuse. The substance may affect diabetics’ insulin needs. Overdose symptoms are similar to those of amphetamine: hyperactivity, fear, aggression, hallucination.
Abuse factors.
Phendimetrazine is a chemical relative of amphetamine and is therefore considered addictive. In an experiment using rhesus monkeys to measure phendimetrazine’s addictive potential, however, the test animals indicated no interest in it. This same study showed the drug having about 10% to 20% of dextroamphetamine’s potency.
Drug interactions.
Drinking milk can counteract phendimetrazine’s anorectic quality. The drug can dangerously increase blood pressure by interacting with monoamine oxidase inhibitors (MAOIs, found in some antidepressants and other medicine). After highly publicized incidents of adverse effects associated with combination therapy of phentermine and fenfluramine, medical practitioners became especially alert to any problems associated with diet drugs. Someone taking phendimetrazine two times a day developed heart and lung difficulty that substantially improved when dosage was halted, and a case of temporary skin rash and kidney inflammation is reported from someone who was taking phendimetrazine and phentermine. The latter drug combination is also suspected of responsibility for temporary trouble with blood circulation in the brain (leading to a stroke in at least one instance). Whether these isolated cases can be extrapolated into general principle is questionable, but such reports raise questions worthy of further scientific investigation.
Cancer.
Not enough scientific information to report.
Pregnancy.
Impact on fetal development is unknown. The drug is not recommended for pregnant women.
Additional scientific information may be found in:
Hadler, A.J. “Sustained-Action Phendimetrazine in Obesity.” Journal of Clinical Pharmacology
8 (1968): 113–17.
Mazansky, H. “A Review of Obesity and Its Management in 263 Cases.” South African
Medical Journal 49 (1975): 1955–62.
Ressler, C., and S.H. Schneider. “Clinical Evaluation of Phendimetrazine Bitartrate.”
Clinical Pharmacology and Therapeutics 2 (1961): 727–32.
Rostagno, C., et al. “Dilated Cardiomyopathy Associated with Chronic Consumption
of Phendimetrazine.” American Heart Journal 131 (1996): 407–409.
Runyan, J.W. “Observations on the Use of Phendimetrazine, a New Anorexigenic
Agent, in Obese Diabetics.” Current Therapeutic Research: Clinical and Experimental
4 (1962): 270–75.
Sash, S.E. “Anorectic Effects of OBEX LA (D-Phendimetrazine Bitartrate) in the Treatment
of Obesity.” Current Therapeutic Research: Clinical and Experimental 31 (1982):
181–84.
