This section is from the book "A Text-Book Of Pharmacology, Therapeutics And Materia Medica", by T. Lauder Brunton. Also available from Amazon: A text-book of pharmacology, therapeutics and materia medica.
stoppered bottles, in a cool place.
Characters. - Shining, lemon-yellow, crystalline scales, somewhat greasy to the touch; having a persistent and disagreeable odour and flavour.
Solubility. - Very slightly soluble in cold water, more soluble in rectified spirit, soluble in chloroform or ether, readily and entirely soluble in warm ether; the solutions being neutral to litmus paper.
Reactions. - When heated it first melts to a brown liquid, then gives off brown and violet vapours, leaving a black residue which entirely disappears on continued ignition. Warmed with an alcoholic solution of potash and the resulting fluid acidified by nitric acid, iodine is liberated, the mixture acquiring a brown colour, or, when cold, a blue colour on the addition of mucilage of starch.
Dose. - 1/2 - 3 grains.
Preparations. B.P. Suppositoria Iodoformi..............................3 grains in each suppository.
B. and U.S.P. Unguentum lodoformi (with benzoated lard)...l part in 10.
As an inhalation in phthisis, a solution may be used containing 20 grains of iodoform, 20 minims of oil of eucalyptus, or 10 of creasote, 1/2 fl. oz. rectified spirit, and 1/2 fl. oz. of ether. This is used with an inhaler of horsehair matting lined with cotton-wool, on the interior of which the solution is dropped (Dreschfeld).
As an external application it may simply be dusted over the sore and covered with cotton-wool, or cotton-wool may be soaked in an ethereal solution of it and then dried. The quantity of iodoform in the cotton-wool should be at least 10 per cent. It may be applied to the nose or throat as snuff, or mixed with half its weight of starch as insufflation, or an ethereal solution may be applied as spray. The nozzle of the spray-producer is apt to become choked and must be washed out frequently with pure ether. It may also be applied to the nose in the form of a bougie containing 1/6-1/2 a grain made up with gelatin and glycerin. In gonorrhoea, bougies composed of iodoform 5 grains, oil of eucalyptus 10 minims, and cacao-butter 35 grains, are useful in the acute stage.
Action. - Iodoform destroys bacilli, and is an antiseptic and deodorizer of very considerable power. It also destroys leucocytes. When applied in substance or strong solution it produces no local irritation, but acts as a local anaesthetic. Its power in this respect is so great that a suppository containing it when introduced into the rectum may so diminish sensibility that defaecation may occur without the knowledge of the person or animal (Wood).
Its absorption from the intestine is probably aided by fat.
It weakens the circulation when taken for some time, and (when applied to the frog's heart it has a powerful paralysing action on the cardiac ganglia in the same way as chloral and iodal (p. 323).
It has a marked action on the nervous system. In cats land dogs it produces narcosis, but not in rabbits. In man it may be absorbed from wounds and affect the nervous system, but instead of producing sleep or anaesthesia, as in dogs, it usually pauses, in slight cases of poisoning, sleeplessness, headache, irrita-ility, and loss of memory. In severe cases it produces maniacal attacks, hallucinations, or melancholia.
These disagreeable effects appear to be diminished by bicarbonate of potassium or sodium in doses of 10 grains hourly.1 It appears to have an extraordinary power to prevent the development of giant-cells, and may thus prevent morbid tissue-growth.
Uses. - Its local anaesthetic and antiseptic actions render it useful as a dressing after operations instead of carbolic acid, and it is especially useful where a regular antiseptic dressing cannot be applied, as in operations on the bladder or rectum, or wounds or ulcers of these parts. It is a most useful application to poisoned wounds, chancres, phagedenic or syphilitic sores, and to fungating growths generally. It induces healthy action in indolent sores. In deep-seated infiltrations of lupus it is used after the epidermis has been macerated and removed by the action of a strong solution of potash. It lessens the discharge and disagreeable smell of ozaena. It has been used as a vapour in cases of phthisis, and also given internally, but with doubtful result: an ointment, 1 in 5, has been found useful rubbed into the scalp in tubercular meningitis.
1 Behring, Wien. med. Blatt, 1884, No. 9.
Methylal. Vide Appendix.
Urethane. Vide Appendix.
Iodol. Vide Appendix.