Pharmacopoeia - Medical Preparations, Uses and Dosages

Medical Preparations, Uses and Dosages

Though formerly printed there has been a transition to a situation where pharmaceutical information is available as printed volumes and on the internet. The rapid increase in knowledge renders necessary frequent new editions, to furnish definite formulae for preparations that have already come into extensive use in medical practice, so as to ensure uniformity of strength, and to give the characters and tests by which their purity and potency may be determined. However each new edition requires several years to carry out numerous experiments for devising suitable formulae, so that current pharmacopoeia are never quite up to date.

This difficulty has hitherto been met by the publication of such non official formularies as Squire's Companion to the Pharmacopoeia and Martindale: The complete drug reference (formerly Martindale's: the extra pharmacopoeia), in which all new remedies and their preparations, uses and doses are recorded, and in the former the varying strengths of the same preparations in the different pharmacopoeias are also compared (Squire's was incorporated into Martindale in 1952). The need of such works to supplement the Pharmacopoeia is shown by the fact that they are even more largely used than the Pharmacopoeia itself, the first issued in 18 editions and the second in 13 editions at comparatively short intervals. In the UK, the task of elaborating a new Pharmacopoeia is entrusted to a body of a purely medical character, and legally the pharmacist does not, contrary to the practice in other countries, have a voice in the matter, notwithstanding the fact that, although the medical practitioner is naturally the best judge of the drug or preparations that will afford the best therapeutic result, he is not so competent as the pharmacist to say how that preparation can be produced in the most effective and satisfactory manner, nor how the purity of drugs can be tested.

The change occurred with the fourth edition of the British Pharmacopoeia in 1898. A committee of the Royal Pharmaceutical Society of Great Britain was appointed at the request of the General Medical Council to advise on pharmaceutical matters. A census of prescriptions was taken to ascertain the relative frequency with which different preparations and drugs were used in prescriptions, and suggestions and criticisms were sought from various medical and pharmaceutical bodies across the British Empire. As regards the purely pharmaceutical part of the work a committee of reference in pharmacy, nominated by the pharmaceutical societies of Great Britain and Ireland (as they were then), was appointed to report to the Pharmacopoeia Committee of the Medical Council.

Some difficulty has arisen since the passing of the Adulteration of Food and Drugs Act concerning the use of the Pharmacopoeia as a legal standard for the drugs and preparations contained in it. The Pharmacopoeia is defined in the preface as only "intended to afford to the members of the medical profession and those engaged in the preparation of medicines throughout the British Empire one uniform standard and guide whereby the nature and composition of, substances to be used in medicine may be ascertained and determined." It is obvious that it cannot be an encyclopaedia of substances used in medicine, and can only be used as a standard for the substances and preparations contained in it, and for no others. It has been held in the Divisional Courts (Dickins v. Randerson) that the Pharmacopoeia is a standard for official preparations asked for under their pharmacopoeial name. But there are many substances in the Pharmacopoeia which are not only employed in medicine, but have other uses, such as sulphur, gum benzoin, tragacanth, gum arabic, ammonium carbonate, beeswax, oil of turpentine, linseed oil, and for these a commercial standard of purity as distinct from a medicinal one is needed, since the preparations used in medicine should be of the highest possible degree of purity obtainable, and this standard would be too high and too expensive for ordinary purposes. The use of trade synonyms in the Pharmacopoeia, such as saltpetre for purified potassium nitrate, and milk of sulphur for precipitated sulphur, is partly answerable for this difficulty, and has proved to be a mistake, since it affords ground for legal prosecution if a chemist sells a drug of ordinary commercial purity for trade purposes, instead of the purified preparation which is official in the Pharmacopoeia for medicinal use. This would not be the case if the trade synonym were omitted. For many drugs and chemicals not in the Pharmacopoeia there is no standard of purity that can be used under the Adulteration of Food and Drugs Act, and for these, as well as for the commercial quality of those drugs and essential oils which are also in the Pharmacopoeia, a legal standard of commercial purity is much needed. This subject formed the basis of discussion at several meetings of the Pharmaceutical Society, and the results have been embodied in a work entitled Suggested Standards for Foods and Drugs, by C. G. Moor, which indicates the average degree of purity of many drugs and chemicals used in the arts, as well as the highest degree of purity obtainable in commerce of those used in medicine.

An important step has also been taken in this direction by the publication under the authority of the Council of the Pharmaceutical Society of Great Britain of the British Pharmaceutical Codex, in which the characters of and tests for the purity of many non-official drugs and preparations are given as well as the character of many glandular preparations and antitoxins that have come into use in medicine, but have not yet been introduced into the Pharmacopoeia. This work may also possibly serve as a standard under the Adulteration of Food and Drugs Act for the purity and strength of drugs not included in the Pharmacopoeia and as a standard for the commercial grade of purity of those in the Pharmacopoeia which are used for non-medical purposes.

Another legal difficulty connected with modern pharmacopoeias is the inclusion in some of them of synthetic chemical remedies, the processes for preparing which have been patented, whilst the substances are sold under trade-mark names. The scientific chemical name is often long and unwieldy, and the physician prefers when writing a prescription to use the shorter name under which it is sold by the patentees. In this case the pharmacist is compelled to use the more expensive patented article and the patient complains of the price. If s/he uses the same article under its pharmacopoeial name when the patented article is prescribed s/he lays oneself open to prosecution by the patentee for infringement of patent rights. The only plan, therefore, is for the physician to use the chemical name (which cannot be patented) as given in the Pharmacopoeia, or for those synthetic remedies not included in the Pharmacopoeia, to use the scientific and chemical name given in the British Pharmaceutical Codex.