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Coffee and cold feet.

A colleague, during a recent physical examination remarked to his physician that his feet remained cold for long periods, even when he slept under an electric blanket. His doctor told him not to worry--he had just the medication for that condition. He gave him a prescription for "TRENTAL (R) tablets each containing 400 milligrams of medication. "Take one three times a day after meals, and in two or three months your problem will disappear."

When my associate read the descriptive circular that came with the medication, he was startled to learn that the active ingredient was a fairly close homolog of caffeine--particularly since his physician was a strong anticaffeine advocate and regularly advised him to limit or even discontinue his intake of this stimulant, even though he had no medical reason for interdicting it. When he informed me of his situation, it appeared to be an interesting case history that merited closer inspection.

The medication prescribed is patented, trade marked, manufactured and marketed by Hoechst-Roussel, the pharmaceutical division of the giant German chemical company, Hoechst A.G. Chemically, each table contains the active ingredient, Pentoxy-fylline De-Methyl - Xanthine, which is first cousin to caffeine, which is chemically Tri-Methyl Xanthine.

Xanthine is a chemical structure consisting of two adjacent rings--one containing two nitrogen atoms and four carbon atoms, and the other containing two nitrogen and three carbons. As coffee beans, tea leaves, and Kola nuts grow, they add three methyl (CH3) groups as side chains to the Xanthine backbone and store this caffeine to ward off animal predators.

The background relationship between these compounds goes back almost two centuries. Caffeine was one of the earliest organic chemicals to be extracted, purified and characterized from vegetable sources. It was first extracted from tea and given the name "Theine". A few years later what was thought to be a different compound was isolated from coffee and titled "Caffeine". Some years later these two compounds were discovered to be identical, and early organic chemists agreed to adopt the standard name "Caffeine" for both. Laterthe same compound was found in MATE leaves, Guarana paste and Kola nuts.

Meanwhile, similar but not identical compounds were found in cocoa and tea. Eventually their structure formula was determined and they were also found to be derivatives of Xanthine, but with only two methyl groups in different positions on the side chains; one was named Theobromine and the other Theophylline. All had similar pharmacological properties which differed only in intensity due to the nature and position of the side chains. Thus, caffeine had greater cerebral stimulating properties, while Theophylline and had improved respiratory stimulation.

In the middle of this century, Hoechst commenced a long program of research on synthetic members of this family. They investigated hundreds of homologs of caffeine, looking for unusual properties. They finally selected one which had a low degree of three toxicity and relaxed arterial blood vessels two to three more times more than the natural Xanthines This would have the effect of increasing blood flow through the arteries, warming the extremities in cold weather.

The compound of choice was to have one of the-methyl groups replaced by a longer side chain containing an oxygen atom with the rest of the molecule being a di-methyl Xanthine. Effectiveness of this new compound was demonstrated by the rabbit ear test, wherein the flow of blood from a priced ear of a rabbit given the medication was several times greater than an unmedicated animal.

One serious problem remained in the marketing of this prescription pharmaceutical. Patents had been granted for the compound and its use, but it had to be given a generic name for the protection of its trade name, and identification of the compound. In this day and age, emphasizing its identity as a Xanthine derivative would be practically a kiss of death with all anticaffeine propaganda prevalent. Associating it with caffeine in this manner would immediately alert every M.D. to its relationship, and many would hesitate to prescribe it.

Organic compounds of this nature are so complex that they can be called any one of half a dozen or more different names and still have a high degree of accuracy comprehensible to organic chemists, but not necessarily recognizable by physicians. Although the latter must pass a course in organic, they have so much to remember about medications--dosage, side effects, toxicity, etc.--that the first thing they forget, after completing the course, is structure. Caffeine is one of the few they do not forget as the Xanthines are among the earliest organics they study and one of the most dramatic groups, so Hoechst knew that a Xanthine product was unlikely to be successful.

They could have called it a derivative of di-oxo-purine, since this is an alternate name for Xanthine. But Purine is a protein decay product and has strong negative connotations. Several other organic names had equal objections. Finally they settled on "Pentoxifylline" which is pleasant sounding and somewhat familiar.

The recommended daily dose is also significant. Each tablet contains 400 mg. of active ingredient and is to be taken three times a day. Although it has a wide margin of safety, 1,200 mg total per day is a fairly hefty dosage for a Xanthine. When you consider that if this were caffeine, it would be equivalent to 12 cups per day at 100 mg. per cup. Manufacturer's directions note that results would be observed in three to six weeks, although the physician suggested it be taken for at least six months.

Side effects were reported by the manufacturer in less than 1% of a group of several hundred patients in a clinical survey. Comments received included mild digestive disturbances such as abdominal discomfort, belching, bloating, dispepsia, diarrhea and occasional nausea; nervous system effects such as agitation, dizziness, drowsiness, blurred vision; and angina, chest pains, arrhythmia, palpitation and flushing. In most cases, these symptoms disappeared when dosage was reduced to two tablets per day.

Trental and its metabolites is believed to exercise its foot warming mechanism through two mechanisms: By dilating the arterial vessels, thus lowering blood pressure and increasing circulation; and by lowering uiscosity of the blood with the same general effect. Since caffeine probably also exhibits this Xanthine effect, but to a lesser degree, it may also have the same beneficial effect on cold feet, particularly on cold winter nights. Since it may cause insomnia if taken at night, it would be inappropriate to have caffeine beverages for this purpose at bedtime.

Figuratively coffee has long been known as aid in overcoming "cold feet" for individuals getting up enough courage or resolve to attack or overcome an unpleasant or undesirable task.
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Title Annotation:xanthine chemical structure common to both caffeine and Trental, a medication used to treat cold extremities
Author:Lee, Samuel
Publication:Tea & Coffee Trade Journal
Article Type:Column
Date:Apr 1, 1992
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