This section is from the "A Practical Treatise On Materia Medica And Therapeutics" book, by Roberts Bartholow. Also available from Amazon: A Practical Treatise On Materia Medica And Therapeutics
Caffeine. A feebly basic, proximate principle, obtained from the dried leaves of Camellia sinensis Linné (Nat. Ord. Tern-stroemiacece), or from the dried seeds of Caffea arabica Linné (Nat. Ord. Rubiaceae), and found also in other plants.
Citrated caffeine. A white, odorless powder, having a purely acid taste and an acid reaction. Dose, gr. ij to gr. x.
Effervescent citrated caffeine. This contains, with caffeine and citric acid, the materials for efferves-cence—sodium bicarbonate and tartaric acid. Dose, a tea spoonful in two or more ounces of cold water, and drunk while effervescing.
The salt of caffeine most worthy of consideration is the hydrobro-mate. This should not be confounded with certain proprietary compounds—more truly, mixtures—that consist of caffeine and bromides.
Some new salts of caffeine have been lately brought forward and are probably improvements on those heretofore available. They consist of sodio-salicylate, sodio-benzoate, and sodio-cinnamate of caffeine. These are soluble combinations, and can be given subcutane-ously without causing local irritation. The dose for stomachal administration ranges from gr. ij to gr. xv.
Ethoxy-caffeine is a substitution product of considerable promise —ethyl replacing one atom of hydrogen in caffeine. According to Dujardin-Beaumetz, this is an excellent hypnotic and calmative. It is crystalline, has basic properties, and, although insoluble in water, its salts can be dissolved with readiness. The following formula is a convenient one for extemporaneous use: Rx Ethoxy-caffeinae, gr. iv; sodii salicylat., gr. iv; aquae lauro-cerasi, 3 jss; syrupi, oz ss. M. Sig.: A table spoonful as required. The addition of one and a half grain of cocaine is recommended by Dujardin-Beaumetz to increase its hypnotic action.
The so-called "citrate of caffeine" is not a chemical combination, but a mere mixture, and is recognized by the present Pharmacopoeia as "citrated caffeine."
Caffeine crystallizes in needle-shaped crystals and in prisms. It is bitter in taste, soluble in water and in alcohol. It is remarkable for the quantity of nitrogen it contains, surpassing in this respect all other alkaloids.
Caffeine in small quantity acts as a stomachic tonic, and rather improves than lessens appetite when administered in diseased states. It is feebly laxative, owing probably to its action in stimulating the glands of the mucous membrane, thus increasing secretion.
The most important function is its action on the heart and circulation. We owe more especially to Dr. Huchard and Professor Sée the modern experience in regard to its place as a cardiac remedy. It has not usually been given in quantity sufficient to produce the appropriate effects, and until recently its powers as a substitute for digitalis were not appreciated. For making a satisfactory impression on the organs of circulation not less than five grains at a dose, and fifteen to twenty grains in twenty-four hours, are required. In sufficient quantity caffeine slows the heart, lengthens the interval, and increases the power of the muscular contraction. It also raises somewhat the arterial tension by stimulating contraction of the arterioles, and it has distinct and available diuretic property. Excessive and too frequent administration of caffeine will bring on toxic effects, in which the heart becomes weak and irregular, the pressure falls, and respiration fails, death being due to paralysis of the respiratory muscles.
As regards the action of caffeine on the brain, it may be stated that, at first, drowsiness occurs; but this is soon followed by wakefulness, excitement, muscular trembling, confusion of mind, hallucinations, and delirium. The cerebral effects terminate in deep sopor, but this is probably the result of exhaustion. Rise of temperature, convulsions, general paralysis, occur when toxic doses are administered to animals; but the temperature declines when paralysis supervenes (Leven, Schmiedeberg, Bennett, and others).
Caffeine is a useful stomachic tonic. In convalescence from acute maladies it is in a high degree serviceable, given to promote the constructive metamorphosis. Chronic catarrh of the stomach, with occasional attacks of migraine, is a combination of maladies in which caffeine is especially useful. Paullinia or coca may be used instead.
In the diarrhoea of phthisis, in ordinary atonic diarrhoea, in cholera infantum, and in cholera morbus, produced by agencies affecting the nervous system, the remedies of this group, especially caffeine, are often extremely useful. When the vital powers are depressed, and when there is at the same time an abnormal excretion of urea—a condition of things which exists in incipient phthisis, associated with indigestion—caffeine, coca, and paullinia are in a high degree serviceable. They increase the appetite and the digestive power, and diminish tissue-waste.
Black coffee, or caffeine, increases the action of the heart and raises the arterial tension, and is therefore useful when the circulation is depressed from various causes.
An important use of caffeine, at present, is in the treatment of headache. It is adapted especially to the relief of migraine, the so-called nervous headache, accompanied with or without stomach-derangement. In this disorder we may administer a grain of caffeine every half-hour, until the headache is relieved; or the bromhydrate of caffeine may be given in an effervescent draught. Elegant and useful are the granular, effervescent preparations of caffeine. They may be prepared extemporaneously by adding caffeine to the materials for effervescence —sodium bicarbonate and tartaric acid.
Caffeine has proved very useful in cardiac dropsy/ and in renal dropsy in inverse ratio to the amount of damage suffered by the kidneys, for, as Brackenridge has shown, this remedy does not increase the flow of urine when the renal epithelium is destroyed. It may be used with advantage in ascites when any diuretic will prove serviceable. It has, within the past two years, been much employed by the French therapeutists, in place of digitalis, in the treatment of certain cardiac affections. According to Huchard, caffeine acts more rapidly than digitalis, causing free diuresis in twenty-four hours. It slows the pulse and raises the arterial tension, thus effecting a better distribution of the blood. To bring about these desirable effects, Huchard rapidly increases the dose, so that on the third day he gives a gramme (15½ grs.) hypodermatically.
The author can confirm the observations of Dr. Huchard, by his own experience in the use of caffeine in cases of mitral incompetence with general dropsy. Having the same kind of action on the heart, not cumulative, and unirritating as digitalis, he has obtained as good results, and with far less discomfort to the patient, with caffeine.