ORTHOFORM. — Orthoform is the methyl-ester of meta-amido-para-oxy benzoic acid. It occurs as a white, or light, dirty-yellow, odorless powder, slightly soluble in water, and easily dis solved in glycerin or in water acidulated with hydrochloric, nitric, or acetic acid. It is feebly antiseptic, and has no poison ous properties. When applied to mu cous or abraded surfaces, it exerts an anesthetic and analgesic action, which generally lasts at least twenty-four hours.
Preparations and Doses.—E. S. Yonge (Brit. Med. Jour., Feb. 5, 'OS) gives the following as being the most suitable preparations:— 1. The crude powder, either alone or mixed with equal parts of lycopodium, which should be accurately insufflated upon the required area, since orthoform takes effect only on contact and does not extend beyond.
2. Pastilles: Orthoform, 3 to 5 grains; solution of cochineal, q. s.; saccharin, grain; glyco-gelatin, q. s. These pastilles are useful in oral, tonsillar, and post-pharyngeal affections, but less so than the two preceding preparations.
3. Orthoform-collodion: A saturated solution of orthoform in collodion, form ing a species of "varnish." This is use ful in ulcers exposed to much friction; but, as it causes acute smarting, it is ad visable to anaesthetize the ulcer first, either with cocaine or with orthoform in powder.
4. Spray: Orthoform, 5 grains; alco hol, 50 minims; water, 50 minims. This is used in spray and is, perhaps, the best form for treating nasal and laryngeal ulcerations. The alcohol evaporates quickly after contact with the parts, leaving the precipitated powder evenly distributed over the affected area.
5. Ointment (10 per cent.).
G. Aqueous solution (10 per cent.) of the hydrochloride as a paint.
Physiological Action.—Orthoform is said by Kallenberger to be absolutely free from any toxic property, and conse quently may be used with perfect free dom. When it comes in contact with sensory nerve-filaments it has a power ful anaesthetic effect, which persists in some instances for three or four days; on account of this property it is an ex cellent dressing for burns or painful ul cers. Another important property is its
inhibiting effect upon secretion, and in case of carcinomatous ulcers or of trans plantation-wounds the dressings remain so dry that they seldom require renewal.
Recent experiments by Soulier and Guimard, however, showed that in the dog a dose, by mouth, of orthoform which exceeds fifteen grains per 2 pounds of body-weight is to be con sidered toxic. But warm, 1-per-cent. solutions of orthoform, injected into the peritoneal cavity, produce toxic effects in the dose of 3 grains per 2 pounds of weight. The substance may, indeed, cause death in six minutes if it reach the dose of grains per 2 pounds.
The action of orthoform, after injec tion, is that of a powerful cerebro-spinal nerve-depressant. Its local action, on the other hand, requires direct contact with the nerve-endings. Soulier and Guimard consider that orthoform is an analgesic, in the true sense of the word, rather than an anmsthetic.
Peculiar necrotic process noted appear ing in the course of three to fourteen days after the application of orthoform to tumors, ulcerations, wounds, etc., and retrogressing when the orthoform was stopped. The first inflammatory stage of the process produced metastases in six cases, by reflex action or by the cir culation, terminating in the necrotic stage. In the nine cases reported ortho form at first produced its usual favor able effect. In numerous other cases in . which it was used both internally and externally there were no unpleasant re sults from its use. W. Asam (Munch. med. Woch., Feb. 21, '99).
Orthoform sometimes produces a de cided irritating effect on the skin. When used in solution it excites hypermmia, and sometimes severe pruritus. When used in the form of an ointment it not infrequently caused, in the course of one or two days, a pruritic eruption.