Remedies may be applied externally to the skin or internally to many mucous membranes, either as a local application or to bring about systemic action.

Methods of Skin Medication. - The passage of drugs through the unbroken skin takes place in a small degree only. The following methods are applicable: Enepidermic method, consisting of the application of cataplasms, fomentations, washes, vapor-baths, etc. Epidermic methods, or the methods of inunction; these are widely applicable. In such the drug is dissolved or suspended in some oily or fatty medium and made to penetrate the deeper layers of the skin by persistent and thorough rubbing. The thinner skinned portions of the body, such as the axillae, groins, beneath the knee, and inner elbow surfaces are those most frequently used. The method is valuable for general absorption, especially in the mercurial administration for syphilis and in the use of methyl salicylate (oil of wintergreen) in rheumatism, but it lacks precision in dosage. Endermic method, by which the skin is blistered and the drug is applied to the free corium; it has many serious disadvantages.

Hypodermic Method. - This consists in injecting the drug into the subcutaneous tissues by means of the hypodermic needle and syringe. Since absorption by the tissues takes place readily, it will be seen that this method of application is far more efficacious than those previously mentioned. Not all drugs, it is to be observed, are available for administration by the hypodermic process of injection. The eminent success attending the operation, however, renders it of signal value to the physician.

This method was first used in a practical manner by Wood, of Edinburgh, in 1853. A syringe with glass rod and glass barrel accurately ground is the best now on the market. If carefully made, it will not leak and is never out of order. Those with metal barrels and leather washers dry out when not in constant use, and are never in condition when required. The all-glass syringe, moreover, can be sterilized at any time. This cannot be said of other varieties. A barrel holding about 30 minims is the usual size. After filling, all air should be excluded. The skin should be pinched up slightly, and the needle inserted rapidly and obliquely; some prefer to insert the needle at right angles, but this is unnecessary, and if contaminated solutions should happen to be used, deep abscesses are produced. The insertion of the deltoid, outer aspect of the thighs, and deep muscles of the back are favorite sites. Solutions of drugs should not be used. It is preferable to use soluble hypodermic tablets; these are best dissolved in a teaspoonful of water heated over a flame; after cooling, the solution can be injected without causing pain. Prompt action follows this method, accurate dosage is assured, and disturbance of the gastric or intestinal mucosae is avoided. As a rule, the dose by this method is 25 per cent. less than when given by the mouth.

Vaccination is a method of skin medication. In males it is best performed over the insertion of the deltoid, and in females there or at the upper outer portion of the leg. The thigh is troublesome to dress and necessitates greater exposure. For scarification the best instrument is a fine needle, which should be sterilized in a flame before using. The site selected should be cleansed thoroughly with soap and water; hard rubbing will aid in peeling away bacteria infected epidermis. Three or more scratches, 1/8 of an inch apart and 1/8 of an inch long, are then made, and the vaccine is rubbed in thoroughly either with a sterilized wooden toothpick or with the glass of a capillary tube. The capillary tube of glycerinated bovine lymph with a small balloon to expel the virus is the best form of virus now in use. With bovine virus the dangers from syphilis and tuberculosis are nil, and thorough cleansing of the arm avoids erysipelas or other septic infections.

Hypodermoclysis is a method of applying remedial agents through the skin. As a rule, 0.6 per cent. normal salt solution is used - a dram of table salt to a pint of boiled and filtered water. The site preferred is the anterior wall of the abdomen or the iliolumbar region, above the ilium and below the ribs. Thorough asepsis is necessary in the technic. An ordinary fountain syringe with a moderate sized needle is all that is required. The solution is best used at a temperature of from 110 to 115o F., and from 4 to 8 ounces are employed. The method is extremely useful in conditions of shock, hemorrhage, diarrhea, uremia, and in toxic states generally.