This section is from the book "A Treatise On The Materia Medica And Therapeutics Of The Skin", by Henry G. Piffard. Also available from Amazon: A Treatise On The Materia Medica And Therapeutics Of The Skin.
"I cannot, then, give my assent to the views of this writer. But it is, nevertheless, quite true that arsenic has a decided curative action in cases of psoriasis, and can make this affection undergo involution for a time, if not permanently. And I must further remark that, although this remedy may be taken regularly for months or even years without the disease being cured (by which I mean, cured permanently as well as for the time), I have never seen it give Tise to any lasting injurious effects, even when given in pretty large doses.
"The following are the preparations of arsenic which, like other dermatologists, I have employed in the treatment of psoriasis and other cutaneous affections: Fowler's solution (arseniteof potass), Pearson's solution (arseniate of soda), Donovan's solution (iodide of arsenic and arseniuret of mercury), the Asiatic pills (made of arsenic and pepper), and lastly, pills of arsenic and opium.
"Fowler's solution (in a drachm and a half of which there is a grain of arsenic) is employed in doses of six drops daily. It is generally given before a meal, either in water, or in some aromatic infusion, such as the Inf. Menthae, the Inf. Melissae. or the Inf. Chamomillae. If it does not disagree with the patient (producing some ill effect, such as nausea, gas-trodynia, or vomiting), the dose may be raised at the end of the first two days by one drop, and at similar intervals it may in this way be gradually increased till it reaches twelve drops daily, by which time some effect will generally be produced. This consists in a diminution of the number scales on the different patches, in a lessening of the redness observed in the maculae after removal of the scales, or in their acquiring a brownish tinge, and, lastly, in the cessation of the itching. The remedy may now be continued in the same dose (twelve drops) for a long period. In cases in which, although well borne, it has produced no change in the cutaneous disease, the quantity may be still farther increased, but at longer intervals (as, for instance, every four days), until twenty drops (2/9 of a grain of arsetiious acid) are given. And if this quantity should give rise to no decided alteration in the psoriasis, there is, in the majority of cases, no reason why the dose should not still be increased, until it amounts to thirty drops a day, or 1/3 of a grain of arsenic; for even so large a quantity as this may be continued for a long time, without any harm being done to the patient. If, however, some smaller dose is found to be sufficient by its producing a favorable change in the affection, that dose should be persevered in until the red maculae have entirely disappeared and have given place to spots of brown pigment, or at least until the disease no longer continues to break out in the punctiform or guttiform state. When this is the case, the quantity may gradually be reduced to the minimum of six drops, with which the patient began.
"I have several times given this preparation for many months without interruption, the quantity taken in a space of about six months exceeding 2,000 drops. And not only has the remedy done no harm to the patient in these instances, but he has been benefited in every respect.
"In other cases, sometimes by way of experiment, sometimes because the arsenite of potass was not well borne, I have employed the solution of Pearson, in praise of which so much has been said. This preparation, the Liquor to Arseniatis, consists of the arseniate of soda dissolved in distilled water in the proportion of one grain to the ounce. Twenty drops contain 1/24 of a grain of the salt. It is therefore much less active than the Fowler's solution, and is given in a dose of forty-five drops daily, or fifteen drops three times a day. It is usual to begin with this quantity, and to continue it without increase or diminution until the above-described changes in the cutaneous disease make their appearance. Another preparation of arsenic mentioned in many books on Dermatology, as well as in those on Materia Medica, is one of Biett's, the solution of arseniate of ammonia. This, like that of which I have just been speaking, contains a grain to the ounce, and it is given in the same way.
Donovan's solution is prepared by rubbing together, in a mortar, 39 1/2 grains of arsenious acid, 76 1/4 grains of pure iodine, and 100 grains of mercury, moistened with a little alcohol, the trituration being continued until the mass has become perfectly dry. To this is then added hydriodic acid, of which a quantity corresponding to 32 1/2 grains of iodine is mixed with four ounces of distilled water. The product is shaken up with three more pints of distilled water and boiled down till a liquid is obtained weighing 1,300 grains. This solution is perfectly transparent, has a high specific gravity, and yields no fixed residue on evaporation. It is given in a mixture which contains a drachm of the solution and half an ounce of syrup of ginger to three ounces of distilled water, and of which three table-spoonfuls are given daily. I have made trial of this preparation in various forms of cutaneous disease, but I have never seen it produce any very good effects.
"The 'Asiatic pills,' on the other hand, are a really good medicine, not only on account of their therapeutical value, but also because there is no difficulty in their preparation, and because their dose can be easily regulated, and they can be given without trouble. They are prepared by mixing 66 grains of arsenious acid and 9 drachms of powdered black pepper with gum-arabic and water, so as to make 800 pills. Each pill therefore contains 0.0825 of a grain of arsenious acid. In most instances it is sufficient to give three pills once a day, the best time for the patient to take them being immediately before dinner. But in cases of obstinate psoriasis, I have sometimes raised the daily quantity to twelve pills (0.99 of a grain of arsenious acid), and have continued this dose for many months without diminution. In this way, it has several times occurred that the patient has taken the enormous quantity of 2,000 Asiatic pills (or more than 1G0 grains of arsenious acid) before he has got rid of the disease. It is, of course, absolutely necessary that persons to whom these large doses of arsenic are being given should be carefully watched, and should be constantly under medical observation. In no instance, however, have I seen any ill effects produced; and therefore I can with confidence recommend to my professional brethren the practice of giving the Asiatic pills, even in such large quantities as I have mentioned, to patients suffering from these intractable diseases of the skin.
"In some cases, again, I have prescribed arsenic in combination with opium, under the idea that it would be more easily borne by the patient when administered in this way. I have ordered, for instance, a grain of arsenious acid and four grains of opium to be mixed with sufficient soap to make sixteen pills, and have given four of these daily, two in the morning and two in the evening. I have continued the administration of these pills likewise for months, and with the desired effect.
"The preceding paragraphs show that I must have made numerous trials of the various preparations of arsenic. I have, in fact, given it to more than 400 patients suffering from different forms of cutaneous disease; so that I can, from my own observation, assert the therapeutic value of this remedy. I can, however, by no means ascribe to it the power of Curing infallibly chronic affections of the skin. To do this, arsenic should be able not merely to cause the disappearance of existing eruptions, but to prevent their recurrence. The fact is, however, that under the employment of each one of its preparations, I have, in different cases, seen the disease break out again or undergo relapse. Thus, while the special action of the arsenic is exhibited by its removing the scales from some of the older patches of a psoriasis, and changing their red color to brown, new spots often continue to break out at points hitherto free from the disease. These remedies, then, possess the power of removing existing eruptions, but are not able to prevent the occurrence of fresh ones. They are, however, the most efficient of all the internal medicines of which I have had to speak, and it may be said that they alone, among these medicines, can by most persons be taken for a great length of time without injury to the health.
"To enable me to give an account of the numerous local applications which have been recommended for the cure of this disease, I must arrange them under different heads.