Handbook of materia medica, pharmacy, and therapeutics : including the physiological action of drugs, the special therapeutics of disease, official and practical pharmacy, and minute directions for prescription writing / by Sam'l O.L. Potter.
- Samuel Otway Lewis Potter
- Date:
- 1897
Licence: Public Domain Mark
Credit: Handbook of materia medica, pharmacy, and therapeutics : including the physiological action of drugs, the special therapeutics of disease, official and practical pharmacy, and minute directions for prescription writing / by Sam'l O.L. Potter. Source: Wellcome Collection.
Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.
43/944 page 37
![Agents Acting on the Organs of Special Sense. Mydriatics (Meudos, moisture),—are agents which produce dilatation of the pupil of the eye (mydriasis). Some act locally, others when given internally, and the principal ones (Atropine and its congeners) act both locally and internally, producing at the same time paralysis of the ciliary muscle resulting in temporary loss of accommodation, the eye remaining focussed for distant objects, and the intra-ocular tension being increased. The principal mydriatics are the following named,— Atropine. Homatropine. Belladonnine (internally only). Gelsemine (locally only). Hyoscyamine. Muscarine. Daturine. Cocaine. Duboisine. Anaesthetics (at last). The dilating action of Atropine and its congeners is due to stimulation of the end- organs of the sympathetic nerve, increasing the power of the radiating muscular fibres ot the iris, and also to paralysis of the end-organs of the motor oculi (3d cranial) nerve, lessening the power of the circular fibres or sphincter iridis. When administered inter- nally the drug is carried by the circulation to the eye, acting thereon locally as if instilled directly upon the conjunctiva. Cocaine acts by stimulating the terminations of the sym- pathetic. Anicsthetics produce mydriasis late in their action, which is central. Atropine, Duboisine and Homatropine are the mydriatics used by ophthalmologists. Myotics {Meuo, I close),—are agents which produce contraction of the pupil. The alkaloid Fhysosiigmine (Eserine) is the chief local myotic, and the only one used in ophthalmic practice. It acts by stimulating the circular muscular fibres of the iris, at the same time contracting the cili- ary muscle so that the eye is accommodated for near objects only, and diminishing intra-ocular tension; in all of which it exactly antagonizes the action of Atropine. Muscarine, Pilocarpine and Nicotine are also local myotics, acting upon the end-organs of the oculo-motor nerve. Ansesthetics in the early stage of their action cause contraction of the pupil by lessening reflex action ; later, when they begin to paralyze respiration the accumulation of venous blood irritates the centres and produces dilatation, which during antesthesia is a sign of failing respiratory power. The myotic action of Opium is ol central origin, probably paralysis of the local reflex excitability. The chief myotics are as follows: — Physostigma, Eserine. Muscarine. Lobeline (internally). Opium, Mor]5hine. Gelsemine (internally). Nicotine (locally). Pilocarpus, Pilocarpine. Carbolic Acid (internally). Anaesthetics (at first). Accommodation is impaired or paralyzed by the following named drugs, acting upon the ciliary muscle, viz.— Atropine. Homatropine. Cocaine. Daturine. Physostigmine. Gelsemine. Hyoscyamine. Pilocarpine. Intraocular tension is increased by Atropine (large doses), Hyoscyamine and Daturine ; and is decreased l)y Physostigmine and by Cocaine. Gelsemine paralyzes the external ocular muscles, especially the levator palpebroe and external rectus, by its action on the terminal nerve filaments.](https://iiif.wellcomecollection.org/image/b24907303_0043.jp2/full/800%2C/0/default.jpg)
