This section is from the book "A Treatise On Therapeutics, And Pharmacology Or Materia Medica Vol1", by George B. Wood. Also available from Amazon: Part 1 and Part 2.
It may be said of opium, in general terms, that, being at first moderately stimulant to the parts to which it may be applied, and to the cir-culation, and energetically so to the nervous system generally, and especially to the brain, it subsequently operates with even greater energy and universality as an apparent sedative. But little idea of the real powers of the medicine would be obtained from such a definition of its effects. In order to form an exact and profitable conception of its influence, so far as known, it is necessary to follow it through the different functions, and trace its operation carefully in each, step by step. Its vast importance, and diversified applicability, call for more minute details than are necessary or advisable in relation to most other medicines. I shall consider it in relation first to the nervous system, secondly to the circulatory and respiratory systems, thirdly to other functions or organs, and fourthly to the part with which it may be directly brought into contact.
From a full dose of opium, taken internally, no other immediate effect is experienced than a slight feeling of warmth, or perhaps of weight in the stomach. But in a short time, varying somewhat according to the form in which the medicine is used, and the state of the stomach, but seldom exceeding ten or fifteen minutes, and often much less, a sensation of fulness is felt in the head, soon followed by a universal feeling of delicious ease and comfort, with an elevation and expansion of the whole moral and intellectual nature, which is, I think, among the most characteristic of its effects. There is not the same uncontrollable excitement as from alcohol, but an exaltation of our better mental qualities, a warmer glow of benevolence, a disposition to do great things, but nobly and beneficently, a higher devotional spirit, and withal a stronger self-reliance, and consciousness of power. Nor is this consciousness altogether mistaken. For the intellectual and imaginative faculties are raised to the highest point compatible with the individual capacity. The poet never has brighter fancies, or deeper feelings, or greater felicity of expression, nor the philosopher a more penetrating or profounder insight, than when under the influence of opium in this stage of its action. It seems to make of the individual. for the time, a better and a greater man. Sometimes there may be delusion; but it is not so much in relation to the due succession or dependence of thought, as in the elevation of the imagination and the soul above the level of reality. The hallucinations, the wildness, the delirious imaginations of alcoholic intoxication, are, in general, quite wanting. Along with this emotional and intellectual elevation, there is also increased muscular energy; and the capacity to act, and to bear fatigue, is greatly augmented.
If the quantity of opium taken has been just insufficient to induce sleep, this delightful exaltation may continue for hours, supporting the mind and body under an amount of exertion, to which they would be wholly inadequate in their ordinary condition.
In two remarkable points, besides those mentioned, the operation of opium differs from that of alcohol; in the absence, namely, of that erotic excitement, and that incapacity of combined muscular movement for a given purpose, which are so strongly characteristic of alcoholic stimulation.
With the psychological phenomena above mentioned, there is very frequently a roaring, singing, or buzzing in the head, of which there is scarcely a consciousness, unless the attention is specially directed towards it. Sometimes these noises, combined with throbbinga or thumpings in the brain, are somewhat disagreeable; but they are seldom sufficiently so to call back the mind from its higher flights, or the spirit from its keen enjoyments.
After a length of time varying, according to the dose of the drug and the susceptibility of the individual, from half an hour, to two, three, or four hours, or even longer, this exaltation sinks into a corporeal and mental calmness, which is scarcely less delicious than the previous excitement, and in a short time ends in sleep. Perhaps, in most instances, where a full dose has been taken, this result occurs within an hour. But, when the quantity of opium is insufficient for this effect, the individual will remain awake for hours, sometimes for many hours, even for the whole night, supposing the drug to have been given at bedtime, lying calmly and placidly, without mental effort or uneasiness, and submitting himself to a current of vague, but generally pleasing fancies.
Should the dose be sufficient only to induce a light sleep, there will be a constant succession of dreams, having the vividness almost of reality. usually pleasant in their character, but sometimes very much the reverse. I have repeatedly known patients to complain of excessively disagreeable effects from opium, and chiefly of horrible dreams with which they have been tormented during the night, and to declare that nothing would ever induce them to take the medicine again; but I have almost invariably found, under such circumstances, that by increasing the dose on a subsequent occasion, or by giving an additional quantity when such symptoms may have presented themselves, that sound sleep is induced, and all discomfort vanishes. So real do these dreams appear, and so much like waking thoughts, that patients will often assert that they have not closed their eyes all night, when the fact is that they have scarcely been awake during that time.
The illusions of opium are so strong that one who uses the drug habitually can sometimes scarcely distinguish them from realities; and I have known intelligent, well educated men, having the ordinary regard for opinion, and perfectly free from any suspicion of insanity, to make statements, in the presence of numbers, as to occurrences which were known to every one present to be impossible, but were as fully believed by themselves as any other event of ordinary life; and I have been able to explain such aberrations, only upon the supposition that the dreams produced by opium had been mistaken for realities. I have no doubt that perfectly truthful persons have thus got the credit of habitual mendacity, when in fact their only immorality was the habitual use of opium, perhaps to relieve sufferings otherwise intolerable.
When opium exercises its full soporific influence, the sleep is usually profound and dreamless, and continues for about eight or ten hours. Should the patient be awakened before the direct effect of the medicine has been exhausted, the feelings of comfort or bienaise before experienced will often continue for hours in the following day; and I have known the same thing to happen repeatedly even after a good night's rest. But generally, upon awaking from the full uninterrupted effects of opium, the patient experiences a state of greater or less depression, indicated by languor and listlessness, a relaxed surface, a rather feeble pulse, and not unfrequently loss of appetite, nausea, and even vomiting. This, however, gradually passes away, and the system returns to its ordinary condition, without having experienced any appreciable disadvantage.
A remarkable diminution of sensibility attends the narcotic operation of opium, beginning even before the soporific effect, and continuing in a greater or less degree throughout the direct action of the medicine, and even into the secondary stage of depression. It is the general sensibility, or that to painful impressions, which is first and most prominently affected; but the special senses are in some degree involved, especially under the influence of very large doses; though I have met with no instance, even of opium poisoning, in which, until the advanced stage when profound coma had set in, the patient could not hear and see when roused. In this respect opium differs strikingly from some other narcotic medicines, and especially belladonna.