7. Untoward Effects

Untoward Effects. Many drugs produce other than their accustomed action upon certain individuals, made abnormal through habit or inheritance; such action results not from any drug impurity, but rather from the difference in the drug's primary and secondary effects (often opposite), the organs chiefly affected by the ordinary action of the drug, and the method of drug elimination. Thus an antipyretic, reducing temperature through the skin (this being connected with and controlled by the central nervous system regulating temperature), may produce skin eruptions or excessive perspiration (untoward) - the drug being eliminated by this channel; and as temperature cannot be controlled without, at the same time, controlling the vasomotor system regulating the blood supply, we also may have collapse, heart failure, palpitation, eye and ear symptoms. If drug is eliminated by kidneys we may have albuminuria, etc. (untoward); hypnotics acting on central nervous system may produce perspiration, skin eruptions, vertigo, heart collapse (untoward); astringents may occasion diarrhoea, bloody intestinal discharges (untoward); diaphoretics from over-stimulation cause local pain, etc. (untoward). Thus aconite may produce eruption or itching of the skin; antipyrine - cyanotic hands, nose, lips, cold extremities; arsenic - dermatitis, burning of the skin, coryza; caffeine - insomnia, delirium, tremors, palpitation, tinnitus aurium, gastralgia; hydrated chloral - nausea, vomiting, purging, inflamed eyes; digitalis - nausea, indigestion, syncope; potassium iodide - coryza, acne; iron - gastric disturbance, headache, constipation; opium - wakefulness, nausea, vomiting, mental depression; pilocarpus - dim vision, vomiting, collapse, swollen salivary glands and tonsils, hiccough, strangling; sali-cylic acid - headache, tinnitus aurium, acne, blindness; cinchona - cinchonism, etc. Powerful drugs (tonics, alteratives, etc.), far more than those comparatively inert, tax the inherited and acquired deficiencies, while excessive and continuous strain on inhibitions usually produce affections of inhibitory apparatus as to modify greatly the untoward effects; these so vary in neurotics as often to cause such nerve-strain of eliminative and assimilative organs as to produce toxins, thereby intensifying or diverting drug's action - etiological moment.

8. Incompatibility

Incompatibility. This often changes the drug's action, producing harmless or harmful compounds, and may be of three kinds:

1. Chemical

Chemical. This results from double decomposition, new compounds being formed, and with the prescriber may be intentional or unintentional: from the former we may have lime water with mercuric or mercurous chloride; zinc sulphate in solution with lead acetate; hydrochloric acid directly to potassium chlorate, etc.; in all these the new-formed product is the one desired medicinally; from the latter (unintentional) we may have glucosides (tannin, etc.) ordered with free acids, or emulsions; alkaloids with alkalies, alkaline salts, iodides or bromides; tannic and gallic acids with iron salts, alkaloids, tartar emetic, albumin, metallic oxides, gelatin; vinegars, acetic syrups, and diluted acid solutions with soluble carbonates; quinine sulphate with potassium acetate; corrosive mercuric chloride with alkalies, alkali carbonates, iodides, bromides, alkaloids, sulphides, reduced iron, silver nitrate, albumin, gelatin, tannin, etc. Any of the following with other substances should also be watched carefully, as they readily cause precipitation and changes: Chlorine solutions, corrosive mercuric chloride, iodine, iodides, lead salts, iron solutions, potassium acetate, bromide, and permanganate, solution of potassium hydroxide, tannic and gallic acids, diluted hydrocyanic acid, mineral acids, quinine sulphate, silver and zinc salts, tincture of guaiac, chlorates, iodates, picrates, nitrates, dichromates. The accompanying table is from Potter's Materia Medica, and serves an admirable purpose in this connection; P. stands for precipitate.

Explosions have resulted by mixing fluidextract of uva ursi or geranium with spirit of nitrous ether; chromic or nitric acid with glycerin; potassium permanganate with glycerin; silver nitrate with creosote; silver oxide with extract of gentian in pill; potassium chlorate with glycerin and tincture of ferric chloride; calcium chloride triturated with sulphur; oxidizing agents with sulphur, charcoal, iodine, phenol, glycerin, turpentine, etc.; iodine with ammonia; potassium chlorate with catechu. Poisonous compounds result from mixing potassium chlorate with its iodide, forming in the system potassium iodate; potassium chlorate with syrup of iodide of iron, liberating in the system free iodine; diluted hydrocyanic acid or potassium cyanide with calomel, forming corrosive mercuric chloride or mercuric cyanide.