Lamellæ. Small thin discs made with gelatin and glycerin, and used to place into the eye. They each weigh 0.0013 gm. (0 of a grain). Lanolinum. This is an ointment having hydrous wool-fat as a basis. Linctus. (Never used in the United States.) A sweet mixture of a thick, syrupy consistence. It is to be swallowed slowly, being retained some time in the mouth. Lotiones (Lotions).-Liquid, usually aqueous, preparations for external use, commonly applied upon lint or muslin. Mollinum.-An ointment having for its basis mollin, a superfatted soap. It is readily absorbed, and also readily washed off with water. Nebula (Sprays).—Solutions sprayed into the throat or nose by means of an atomizer. Oxymellita.-Mellita containing acetic acid. Paste. A preparation to be applied as an ointment. Pastilli (Pastils).—A name often applied to troches, and in England limited to those having glyco-gelatin as a basis. Perles. This is another name for small pills. Pessus. Pessaries are solid preparations made like suppositories for introduction into the vagina. This term is rarely used in the United States. Pigmenta (Paints).-Liquid preparations adapted for painting on the skin, throat, etc. Succi (Juices).-Expressed vegetable juices preserved by the addition of a definite proportion of alcohol. Tabellæ.-(Tablets or Tabloids, the latter of British usage.) Solid, disc-like or lenticular bodies made by compression. "Tablet triturates" are composed of drugs which have been triturated before compression. They are very popular, but are often useless, for they may be so hard and insoluble that they are found in the fæces quite unaltered. Tablets should therefore always be prescribed extemporaneously and freshly made. Vapores.-Liquid preparations intended for administration by inhalation in form of vapor. Vaselinum. This term in England is applied to an ointment of which the base is vaseline. Vina. Wines are practically weak tinctures, the drug being extracted with white wine, containing not less than 7 per cent. nor more than 12 per cent. by weight of absolute alcohol. PRESCRIBING The more complex prescriptions consist of— (1) The Basis, or principal active ingredient (curare). (2) The Adjuvans, or that which assists its action (cito). (3) The Corrigens, or that which corrects its operation (tuto). (4) The Constituens, vehicle, or excipient, or that which imparts an agreeable form (jucunde). Thus, the object of every prescription is to cure quickly, safely and pleasantly. For example, in Pilula Rhei Composita the rhubarb is the basis, the aloes and myrrh form the adjuvans, and the oil of peppermint is the corrigens to prevent the griping. In Mistura Crete the cinnamon water is the vehicle. Many drugs do not require anything to assist their action or correct their operation. The scientific physician usually prefers to administer the remedies separately, in order to more accurately observe their effect, and as well to discontinue, or change the dose of any one which may be necessary. Incompatibility of ingredients should be particularly avoided in prescriptions. There are three kinds of incompatibility: (a) Chemical Incompatibility; e.g., Glucosides should not be ordered with free acids, which decompose them; nor Alkaloids or Alkaloidal Salts with alkalies, alkaline salts, tannic acid, iodides, or bromides, for they precipitate them. Examples of chemical incompatibility are the prescribing of (1) tannic acid or substances containing it with alkaloids or metallic salts, especially those of iron (2) vinegars or syrups containing acetic acid prescribed with carbonates lead to the evolution of carbon dioxide; (3) strychnine sulphate is decomposed by potassium bromide, and strychnine is precipitated; (4) hydrated chloral and alkalies form chloroform; (5) quinine sulphate and potassium acetate together cause a voluminous precipitate of quinine acetate; (6) lime water with mercury salts (this incompatibility is intentional in Lotio Nigra and Lotio Flava) precipitates mercuric oxides; it decomposes carbonates and bicarbonates of alkalies; it precipitates solutions of quinine and morphine salts; (7) corrosive mercuric chloride is incompatible with most substances. With the following drugs it is particularly difficult to avoid chemical incompatibility. Substances rich in oxygen, as chlorates, iodates, permanganates, picrates, nitrates and bichromates should not be mixed with readily oxidizable substances, such as charcoal, sulphur, iodine, phenol, glycerin, turpentine, and organic compounds generally, for explosive compounds are very liable to be formed. Poisonous compounds may be formed by the admixture of substances in solution: e.g., potassium chlorate and the syrup of ferrous iodide liberate iodine; diluted hydrocyanic acid and calomel form mercuric cyanide; potassium chlorate and potassium iodide form, at the temperature of the body, a poisonous compound, probably potassium iodate. Fatal results have been known to occur from the use of prescriptions thus carelessly made. If, in a mixture, incompatibles are inevitable, they should both be diluted with the vehicle before they are added to each other. The careful prescriber will avoid combining any of the above incompatible substances. The following table, by Potter (Materia Medica, Pharmacy and Therapeutics 12th Ed., p. 523) shows the most important instances of solutions which mutually precipitate each other. The letter "P" means "forms a precipitate with." (b) Physical Incompatibility.—This occurs when the mixture of the substances will not form a clear solution; e.g., insoluble powders and oils will not mix with water, the addition of which, to some spirits and all resinous tinctures, and to fluidextract of male fern causes a precipitate; if an acid mixture is flavored with licorice, the acid precipitates glycyrrhizin; an alcoholic solution added to chloral hydrate causes all the chloral to rise to the top. In such cases the aqueous solution may be thickened so that the precipitate is suspended in it to form an emulsion, but even then the mixture must be shaken before a dose is taken. Mucilage of acacia, freshly made, is the best emulsifying agent. The substances incompatible with it are mentioned under Acacia. It should be made perfectly fresh and the addition of a little almond oil improves its appearance. I pt. of most fixed oils requires of acacia 34 pt., water I pt. Tragacanth, because its preparations keep better, is often used to form an emulsion or a suspension, and sometimes yolk of egg or milk is employed. Solution of Potassium Hydroxide greatly facilitates the admixture of fixed oils and water, although it often acts chemically on the ingredients of the prescription. Tincture of senega (not official) aids the emulsification of any oil, even in small quantities, 0.60 mils (10 m); being sufficient for 30 mils (1 fl. oz.), of a fixed oil. Magnesium carbonate is employed to aid the diffusion of an oil in water through which air is to be inhaled. Resinous tinctures require an emulsifying agent; an equal part of mucilage of acacia is the best. (c) Pharmacological Incompatibility; e.g., the combination of purgatives with astringents which check peristalsis. Sometimes this is intentional, as in the addition of atropine to a hypodermatic solution of morphine. After the description of each drug those substances which are incompatible with it will be enumerated. THE PRESCRIPTION The details of a prescription should be written in the following order: The first part is the Superscription, which is the sign R, an abbreviation for Recipe "Take." The second part is the Inscription, consisting of the names of the drugs in the genitive case (the vehicle in the accusative if ad is used with it), and their doses in the accusative. The third part is the Subscription, that is to say, the directions to the dispenser. This in the United States and most other countries is written in Latin, but in France it is in the language of the country. The fourth part is the Signature, namely, the directions to the patient (from the Latin "Signetur," let it be labelled). This is written in English. The fifth part consists of the physician's name or initials at the bottom on the right, the patient's name at the bottom on the left, and under it the date; thus: Superscription.-R. Inscription.-Tincturæ Ferri Chloridi, 12 mils; fl. 3 iij (basis). Glycerini, 60 mils; fl. 3 ij (corrigens). Aquam, ad 240 mils; fl. 3 viij (excipient). Subscription.-Fiat mistura. Signature. Take one tablespoonful three times daily, two hours after meals. A. B. C. (physician's initials). William Smith, Esq. (patient's name). 29th August, 1916 (date). The Federal narcotic laws require that prescriptions written for narcotic and habit-forming drugs shall contain additional information: the date upon which the prescription was written, the patient's name, residence and age, the residence, registration number, office hours and signature of the prescriber, and as well as that a record be made of the prescription and kept for at least two years. Since there are many and conflicting laws every prescriber should familiarize himself with the National, and local State and Municipal laws upon this subject. In countries where the metric system is generally employed the quantities, either of fluids or solids, are expressed in grammes, so that the abbreviation is omitted; 60 meaning 60 gm. or 60 c.c. as the substance may be solid or liquid. In the United States and Great Britain (Pharmacopoeia, 1914) mils should be used instead of c.c. Abbreviations. Although abbreviations are objectionable, yet this prescription could be written thus: R. Tinct. Ferr. Chlor., 12 mils; fl. 3 iij. Quin. Hydrochl., 2 gm.; gr. xxx. Mag. Sulph., 60 gm.; 3 ij. Glycer., 60 mils; fl. 3 ij. Aq., ad 240 mils; fl. 3 viij. F. m. S. Take one tablespoonful thrice daily, two hours after meals. William Smith, Esq. A. B. C. 29th August, 1916. S, ss. and fs. are abbreviations for semi, a half, and āā for ana, of each. Ad. The prescriber should be careful in deciding whether or not to use this word before the vehicle. If it had been left out in the prescriptions given above, the bulk of the mixture would have been nearly 315 mils (101⁄2 fluid ounces) and the amount of the ingredients in each dose would have been less than was intended. The following is a prescription for a pill: R. Extracti Nucis Vomicæ, 0.015 gm.; gr. 4. Aloini, 0.03 gm.; gr. ss. Hydrargyri Chloridi Mitis, 0.06 gm.; gr. j. Extractum Hyoscyami, ad 0.30 gm.; gr. v. S. Take one immediately before dinner every evening. William Smith, Esq. A. B. C. 29th August, 1916. It will be observed that the quantities in the prescription are for one pill only and the apothecary is directed to send 24. Often, however, the prescription is written with the quantity of each ingredient necessary to make the full number of pills. Thus: R. Extracti Nucis Vomicæ, 0.36 gm.; gr. vj. Aloini, 0.75 gm.; gr. xij. Hydrargyri Chloridi Mitis, 1.50 gm.; gr. xxiv. S. Take one immediately before dinner every evening. William Smith, Esq. 29th August, 1916. A. B. C. Prescriptions for powders are also written in either form. The medicine may be prescribed as a pill when it is required that the patient shall carry it about with him, when only a small dose is needed, when it is desirable that it shall act slowly, when it is required to act on the lower bowel, when it is insoluble or nauseous, or when it is difficult to prescribe in the liquid form. |