USES OF CATHARTICS. 133 Reliance on drugs alone will almost inevitably lead to aggravation of the trouble, and an increase of the dose required. The object should be to use the smallest dose possible, to assist it by diet, and, as has been described, to diminish instead of increasing it. In the annoying constipation of otherwise healthy children, active drugs are sedulously to be avoided as long as possible. Attention to diet, the addition of some of the malt foods, a little scraped apple, magnesia, or cod-liver oil, may be mentioned among the means to be tried. A suppository of soap will often provoke the evacuation. For unloading the bowels for a single occasion more active drugs must be chosen. Unfortunately, this is the course usually pursued by those who treat their own constipation, enduring it as long as possible, and then provoking a violent unloading, which leaves the bowels exhausted and in the condition to go through the same process again. Sometimes, however, it is necessary to begin the treatment of constipation in this way, but it must only be a beginning. In pregnant women Confection of Senna, or Compound Liquorice Powder may be used; or, if real need exist, castor oil, although the latter is fairly open to the objection just stated. After delivery the necessity for caution is less, and a full discharge is in the great majority of cases better obtained from castor oil than any other drug. In accumulations in the colon taking place during a long time, and sometimes unsuspected, on account of the presence at the same time of an occasional diarrhoea, it may be necessary to proceed with caution. If it be certain that no organic obstruction exists, the more active cathartics, as a full dose of castor oil, or even croton oil, may be given with rapid relief. Salines, however, especially in moderate and often repeated doses, offer the advantage, under these circumstances, of not producing so much irritation, and of being absorbed if they fail to act as cathartics; so that in cases of doubtful diagnosis they are the safest. The amount of water they bring down is of use in softening and dislodging scy bala. They may be assisted by large enemata of water or oil introduced through the long tube. The cause of the intestinal accumulation must, of course, be carefully diagnosticated if possible. Nothing can be more disastrous than repeated attempts to force a passage through an organic obstruction by drastic purgatives. Rectal impaction is obviously, in most cases, better attacked from below than from above. Irritating ingesta, as undigested food, may be the cause of diarrhoea. The cathartics chosen to remove it are either castor oil, or the aromatic preparations of rhubarb, where the tannic acid exercises an astringent effect after the cathartic has ceased. Foreign bodies, like coins and buttons, should not be followed 134 USES OF CATHARTICS. by a cathartic, but by coarse food forming a large residual mass -. g., brown bread. In dysentery the saline cathartics, probably from their increasing the secretions of the small intestine, are used either in one large dose early in the disease, or in smaller ones combined with opium. The abdominal blood vessels are so capacious that, when filled, a sufficient amount of blood is withdrawn from the general circulation to affect materially the pressure in other parts of the body, and notably the brain. Hence the use of vigorous cathartics, producing congestion of the whole intestinal tract, as well as subtracting a considerable amount of fluid secretions, is a most powerful means of combating intracranial congestion, and affords great relief in headaches or comatose symptoms depending on that condition. This is applicable rather to congestion accompanying gross cerebral disease than to meningitis or the symptomatic headache of typhoid. Many different cathartics are used for this purpose, notably the salines or the compound cathartic pill. When uræmia and dropsy are to be treated by cathartics, those are selected which produce copious evacuation with comparatively little risk of intestinal inflammation. Jalap and elaterium are often used. The dropsy of parenchymatous nephritis must not be too vigorously treated in this way, as the diarrhoea produced may prove too exhausting, and not easily controlled. There is a popular tendency to treat the beginning of many acute diseases with cathartics, which may lead to disastrous results. It is extremely doubtful whether any zymotic diseases are cut short in this way, and an attempt to "work off the disease," by repeated purgation, may simply add to the burden the patient has to carry. Typhoid fever has been treated throughout with repeated doses of salines. All that can be said of such treatment is that it is less fatal than might be supposed. The diarrhoea of a typhoid fever often dates back to the cathartics taken by the patient before he comes under medical observation. At a later period, a clearing out of the contents of the intestinal canal by a mild and unirritating cathartic, like castor oil, has been recomTended, as diminishing the opportunities for reinfection by d matters. A icse of calomel, during the very early days of the fever, eived the sanction of high authority. SECTION X. DIURETICS are drugs which increase the amount of urine. Three factors, singly or combined, conduce to this result: 1. An increase of fluid to be secreted, as after the ingestion of a large amount of watery beverages. The influence of this factor is greatly affected by the relations existing between the secretions of the kidneys, the intestines, the lungs, and the skin, so that, when copious diarrhoea or diaphoresis exists, diuresis is much diminished. 2. The condition of the circulation. A general rise of arterial tension, especially if accompanied by a local dilatation of the renal arterioles, giving a large supply of blood under high pressure, increases the amount of urine. On the other hand, an extreme degree of inflammatory or passive congestion produces diminution, or even suppression of the urine. 3. Direct irritation of the renal structure, whether of the Malpighian capsules or secreting tubes; by substances conveyed thither by the blood. It is not always possible to separate the influence of this third factor from that of the second, at least so far as the renal circulation is concerned, since it is highly probable that many substances, especially the more active ones, which stimulate the renal epithelium, will either directly or indirectly dilate the renal arterioles. The action of the milder and less irritant diuretics, especially salines, renders it probable that, as might be supposed, any substance passing in large quantity through the renal cells provokes them to increased activity. A few drugs, and notably colchicum, have been found materially to increase the amount of solid organic urinary constituents without so much effect upon the water. These have been sometimes spoken of as "true" or "depurative" diuretics. Since, however, the healthy kidneys are abundantly able, without stimulation, to carry off all the products of organic waste, the action of this drug (colchicum) must be looked upon as exerted on the processes of metamorphosis which supply the material, rather than on those of excretion, which only get rid of it, and hence it is no more truly a diuretic than the others. 136 AQUA DESTILLATA. Thus we may have three classes of diuretics with several subgroups. AQUEOUS DIURETICS OR DILUENTS. AQUA.-Water. Common Water, Spring Water. Should contain not more than 1 part of fixed impurities in 10,000 parts. AQUA DESTILLATA.—Distilled Water. Ean Distille, Hydrolats simple, Fr.; Destillirtes Wasser, G. HO. In evaporating one liter of distilled water, no fixed residue should remain. Distilled water is as nearly chemically pure water as can be obtained. Natural water varies from this in the amount of saline constituents in all degrees up to that of the ocean with 3.3 or more per cent., or the Dead Sea with 26.42 per cent. Some mineral springs contain five per cent. Common water is such as contains foreign substances in so small an amount as not to alter the taste and other sensible properties. A certain amount of inorganic matter does not unfit water for domestic, and even some pharmaceutical purposes; but organic material, though possibly harmless, is to be looked upon, especially in thickly settled neighborhoods or near dwellings, with more suspicion. Hard water is that which contains in solution a considerable quantity of magnesia or lime, the latter frequently in the form of bicarbonate. Such water is much less useful for washing, as it does not form a good solution with soap. It may be rendered soft by the addition of a small amount of milk of lime to convert the bicarbonate into the less soluble carbonate. Though perfectly pure water is stated to have been found in the state of nature, it is certainly excessively rare. Rain collected after it has been falling for some time, and in clean vessels, is among the purest of natural waters. It absorbs, however, a little ammonia from the atmosphere, and collects impurities floating in the form of dust. That which first runs from the roof should be rejected. Rain water in the country has been found to contain less than three-fourths of a miligramme of ammonia to the liter, while at Paris four milligrammes were found. Thirty-three milligrammes of fixed residue per liter were found near Paris, consisting of sulphate of lime, chloride of sodium, peroxide of iron, and a nitrogenous matter soluble in ether. Water from snow and ice is nearly pure, but, although ice is purer than the water from which it is formed, it does not get rid of all organic impurities. A considerably larger amount of solid residue than is allowed CHEMICALLY INDIFFERENT WATERS. 137 by the Pharmacopoeia does not prevent water from being, not only fit for use, but very agreeable as a beverage. There are a few spring waters in the United States which come within pharmacopoeial limits, and some of them have a reputation for therapeutic efficacy which is really attributable to the water rather than to any saline ingredient. A much larger number are not sufficiently above the limit to prevent them being considered as "chemically indifferent" waters. The following list gives a few examples: Large numbers of springs, wells, and rivers, more or less known to fame, furnish potable water. Of the water supplies of the large American cities. |