This section is from the book "Materia Medica: Pharmacology: Therapeutics Prescription Writing For Students and Practitioners", by Walter A. Bastedo. Also available from Amazon: Materia Medica: Pharmacology: Therapeutics: Prescription Writing for Students and Practitioners.
Cathartic measures are laxative when employed to produce soft stools of about normal frequency, and purgative when em-ployed to produce copious soft or liquid movements. A hydra-gogue is any remedy that will result in copious watery stools. The term aperient is sometimes employed for any cathartic, but especially for a saline.
The term cholagogue was formerly applied to certain substances which were thought to increase. the production of bile. The amount of bile may be increased by large amounts of ox-gall or bile-salts administered by mouth, and to a slight extent by salicylic acid. It is also increased by the injection of secretin into the blood (Starling). But pharmacologic research has shown that we have no effective agents which, in therapeutic amounts, have this action, so the term had best be abandoned.
Cathartic measures include habit formation, response to the desire to defecate, exercise, massage, food, and drugs.
1. Habit formation is the establishment of a regular time for the daily stool. Usually this time is just after breakfast, both because this is a convenient time and because the activity of dressing and the taking of food both tend to stimulate colon peristalsis. Even when there is no desire to defecate it is advisable to make the attempt; for the voluntary effort may force some feces into the rectum and so result in the proper subjective sensations which bring about the defecation reflexes. The after-breakfast smoke tends to promote defecation.
2. That response to the desire to defecate is important is indicated by Hertz's observation that the rectum accommodates itself to the presence of a fecal accumulation, so that if the desire is not responded to, it will pass away and the defecation reflex become impaired. Many persons have become habitually constipated because their occupation interfered with defecation. Women in business, for example, often suppress the desire to defecate rather than pass a number of men to reach the toilet.
3. The exercises of value are: walking, running, rowing, horseback riding, tennis, golf, gymnastics, and special abdominal exercises. Such are: bending the body forward or backward, or from side to side; lying on the back and raising the legs to a right angle with the trunk, or raising the trunk to a right angle with the legs, etc. It must be noted that there are many persons who live a sedentary life yet are not constipated, and that many athletes and gymnasts have habitual constipation. In fact, exercise is frequently of value only so far as it promotes appetite and thus increases the amount of food eaten.
4. Massage may be either superficial or deep. It may be performed by active kneading in the direction of the colon, by a rotary motion of the abdominal wall over the viscera, by vibratory massage with the hands or a machine, or by rolling a cannon-ball or ball of clay covered with leather or chamois over the abdomen from cecum to sigmoid below the navel in the direction of the hands of a clock. Such a clay ball may be heated.
There is no sharp dividing-line between food and drugs, certain substances acting as food or as drug according to circumstances. A substance cannot serve as nutriment and act as a cathartic at the same time; for if it is absorbed, it does not act as a cathartic, and vice versa. Those who habitually undereat will be constipated.
Foods tend to promote bowel movements by - (1) Chemic stimulation, as of sugars and fruit acids and their salts, and digestive products, such as proteins, amino-acids, soaps, etc; (2) mechanical stimulation, as by seeds or husks; (3) increasing the bulk of intestinal contents, as by cellulose, skins, etc., and un-absorbed oils and fats or their soaps.
Foods of too ready digestibility are constipating. Of enormous importance (Hertz) is cellulose; in fact, Rubner states that "in the absence of cellulose from food almost everything is absorbed."Fruits and vegetables rich in cellulose pass into the intestines as paste and stimulate peristalsis; meat, eggs, and milk pass as liquids and so favor segmentation, but not peristalsis (Cohnheim). Hertz reports that of the dry substance of meat, eggs, white bread, and rice, only 5 per cent. appeared in the feces; while of the dry substance of green vegetables and brown bread 15 per cent., and of the dry substance of carrots and turnips 20 per cent., appeared in the feces. The feces of a mixed diet gave 100 gm. of water and 35 gm. of dry substance; the feces of a vegetable diet gave 260 gm. of water and 75 gm. of dry substance.
Vegetables and salads mostly contain fibrous tissue and cellulose. Many vegetables are as much laxative as nutritive. Salad dressing contains oil, which tends to be laxative.
Cereals contain cellulose. Oatmeal is especially laxative, because of the presence of indigestible husks. Oatmeal water is even said to be more laxative than waters made from other cereals, but no soluble laxative principle has been isolated, and the water lacks the special laxative agent (the husks) of the oatmeal itself.
Fruits contain sugar, cathartic acids or salts, indigestible structural parts (fiber, cellulose, skins, etc.), seeds, and nonabsorbable colloid pectin bodies. Those most frequently considered laxative are prunes, figs, and dates; but an apple, an orange, a banana, or some grapes at bedtime will often insure the morning stool. The morning coffee also promotes defecation.
These are usually administered by mouth, but a few may be employed subcutaneously, and some are used by rectum in the form of enemata and suppositories. Cathartic drugs may be loosely classified as:
A. Those acting by a selective affinity for the nervous structures.
B. Those acting mechanically to give bulk and soft consistency to the feces.
C. Those acting as bowel irritants.
D. The saline cathartics - which have a special action.
In Class A we have: Physostigmine salicylate, dose, 1/60 grain (0.001 gm.), which stimulates the ends of the vagus or motor nerves of the intestines; pituitary extract, which stimulates the muscles; and apocodeine, dose, 1/2 grain (0.03 gm.), which depresses the ends of the splanchnic or inhibitory nerves, thus freeing the bowel from inhibition and increasing its motor activity.
Sulphur increases the bulk of the feces and makes the stool soft. It is partly changed by the proteins of the alimentary tract into sulphides, sulphites and sulphates, which are mildly stimulating to peristalsis. The intestinal gases are increased in their sulphureted hydrogen constituent, and the feces may have a sulphuret odor. Some of the products are absorbed, as shown by the increase of sulphates in the urine.
Sulphur, cream of tartar (potassium bitartrate), and molasses is a favorite household "spring medicine," and tablets may be had containing various proportions of cream of tartar and sulphur. For the blood, in acne, it is given in the form of calcium sulphide, dose, 1 grain (0.006 gm.). Precipitated sulphur and potassa sulphurata are also used in lotions for acne. In scabies sulphur is sprinkled in the bed, and also applied to the skin in ointment form. For room disinfection it is burned to produce sulphur dioxid (So2).
There are three official forms of sulphur, viz.:
Sulphur sublimatum (sublimed sulphur, flowers of sulphur), which is preferred as a laxative, as it contains free sulphurous acid and is gritty.
Sulphur lotum (washed sulphur), which is freed from acid by washing with ammonia, but is gritty. Its 15 per cent. ointment (unguentum sulphuris) is official.
Sulphur praecipitatum (precipitated sulphur), prepared by precipitation from a solution of alkaline sulphide. It is soft and not gritty, and is preferred in lotions.
Agar (Agar-agar) is a form of hemi-cellulose prepared from several species of seaweed. It has the property of absorbing water to form a jelly-like material. After heating 1.5 parts of it with 100 of water it cools to a stiff jelly, which is used extensively in bacteriology as a culture-medium. It is ordinarily unaffected by the digestive fluids, and is not absorbed from the alimentary tract, hence is not a food. But it absorbs water and swells, thus serving the double purpose of carrying water down into the intestines and of increasing the bulk of the colon contents.
Its disadvantages are: (1) It is an excellent culture-medium and may favor the development of intestinal bacteria, itself becoming decomposed; (2) it mechanically retards the absorption of food-products; and (3) by acting as a demulcent it lessens the normal stimulation of the intestine by the food material. To overcome this last disadvantage Schmidt has recommended the addition of cascara, and such a preparation is on the market under the name of regulin. This is slightly bitterish from the cascara, the amount of which is not stated. A teaspoonful to a tablespoonful may be taken at night, or night and morning, dry or with water, or with the morning cereal. Its laxative action is frequently delayed for several days; but after that the patient may continue having a soft daily stool so long as the regulin is taken. Another laxative combination with agar is phenolphthalein-agar, of which one level teaspoonful, weighing 15 grains (1 gm.), contains 1/2 grain (0.03 gm.) of phenolphthalein.
Whole flaxseed and psyllium seeds are sometimes taken in teaspoonful dose to increase the bulk of the feces. Their mucilaginous coat absorbs water and swells. They are fermentative, however, and tend to produce gas and acid.
This petroleum oil, known also as liquid vaseline, liquid albolene, Russian mineral oil, and liquid paraffin, is not absorbed from the alimentary tract (Bradley, 1911, Bloor, 1913), hence serves to soften and to increase the bulk of the feces. It may exert an antiseptic effect on some of the strains of fecal bacteria, but this has not been demonstrated. It has little effect in the stomach, except that, like other oils, it tends to retard stomach emptying and gastric digestion and may nauseate. It is only mildly laxative, and frequently must be given with some stronger laxative, such as cascara. A disagreeable effect in some people is the leakage of free oil from the anus, especially with the expulsion of flatus. This occurs with both the light and heavy oils, and with those of high and low viscosity. The dose is 1 ounce (30 c.c.) two or three times a day, the refined varieties being almost tasteless and readily taken. If desired, aromatics may be added. The author, in an investigation for the Council on Pharmacy and Chemistry of the American Medical Association, found that there was no difference in the clinical effects whether the oils were of low or high specific gravity or of Russian or American origin, provided that they were properly refined. The Pharmacopoeia allows a wide range of specific gravity and has adopted viscosity tests (see Part.I).