Morphina. Morphine.
Related entries: Opium - Poppy Capsules - Cotarnine - Cotarnine Hydrochloride - Morphine - Morphine Acetate - Morphine Hydrochloride - Morphine Sulphate - Morphine Tartrate - Narceine - Narcotine - Red poppy petals - Meconic acid
C17H19NO3, H2O = 303.178.
Morphine, C17H19NO3, H2O, is the principal alkaloid occurring in opium, in which it exists in combination with meconic acid (and probably also with sulphuric acid) to the extent of from 4 to 20 per cent. or even more. It may be isolated by various methods, the final step usually being the addition of ammonia in slight excess to an acid solution of the base, the precipitate being washed with water until free from ammonium salt, and recrystallised from alcohol. It is official in the U.S.P. It occurs in fine, odourless, colourless or white needle-shaped crystals, or as a white, crystalline powder, permanent in air, and having a bitter taste. Its aqueous solution is alkaline to litmus and is laevorotatory. The potassium hydroxide solution should not evolve the odour of ammonia (absence of ammonium salts). It loses its water of crystallisation at about 120°, melts with decomposition at 230°, and on complete ignition it is entirely consumed and leaves no residue. Distilled with potassium hydroxide it yields methylamine. With pure sulphuric acid in the cold it yields no colouration, or only a slightly yellow tint, but on heating a brown colour is developed. Nitric acid produces an orange-red colour fading to yellow. Dissolved in sulphuric acid, made hot by the addition of a few drops of water, and a drop of nitric acid added, a red colour is produced. Sulphuric acid with a trace of molybdic acid yields a purple colour, changing to blue. Sulphuric acid containing one drop of solution of formaldehyde to each mil yields an intense purple colour. A solution of morphine in diluted sulphuric acid produces with potassio-mercuric iodide solution a copious white precipitate. A 5 per cent. solution of sodium phosphomolybdate produces with solutions of morphine a yellow precipitate soluble in ammonia. Sulphuric acid containing a crystal of potassium bichromate yields no colour at first, but after some time a green colour (absence of strychnine, which gives a purple colour). Morphine acts in many cases as a reducing agent. If a solution of morphine be mixed with a solution of starch and gently evaporated on a white porcelain surface, the residue after cooling, on being moistened with iodic acid, will produce a blue colouration. Minute traces may be detected in this way. Morphine solutions added to an aqueous solution of potassium ferricyanide, containing a drop of neutral ferric chloride, give a deep blue solution which, on standing, throws down a blue precipitate (difference from codeine). When boiled with solution of silver nitrate, silver is precipitated. Ten mils of a 1 per cent. solution in diluted hydrochloric acid, yields no red colour on the addition of a few drops of ferric chloride (absence of meconic acid or meconates).
Soluble in water (1 in 5200), boiling water (about 1 in 400), alcohol (1 in 100), boiling alcohol (1 in 14); almost insoluble in ether (distinction from narcotine), chloroform (1 in 4167), benzol (1 in 3250), or acetic ether, not very soluble in amyl alcohol; soluble in oleic acid (1 in 10), glycerin (1 in 125), and in solutions of the caustic alkalies, but very sparingly soluble in ammonia and the alkali carbonates; soluble in acids to form crystalline salts, from solutions of which it is precipitated by ammonia, but not by potassium hydroxide.
Action and Uses.—Morphine and its salts differ from other hypnotics in that they depress sensory nerve cells in the cerebrum, while most other hypnotics paralyse motor and sensory cells simultaneously. The paralysis in the brain occurs in the reverse order of the development of the different parts; thus self-control, judgment, and attention, which represent some of the highest attributes of mind, are some of the first to go. Later, feelings and sensations of all kinds are diminished and a condition of dreamy abstraction is produced followed by drowsiness and sleep. Sometimes there may be delusions, such as prolonged estimation of time and space, rarely is there excitement, but emotional races of Eastern countries, such as the Malays, occasionally develop a kind of mania, and in Europe many cases have been recorded in which women and children, after a morphine injection, have for a time shown signs of violent excitement. Because of this action on the cerebral hemispheres, morphine is the most valuable drug we possess for the treatment of pain. It is of great value as a remedy for sleeplessness due to painful disease. For internal haemorrhage, injections of morphine form a routine treatment; they act by soothing the patient, stopping restlessness, and so keeping blood pressure low. In acute febrile disease, especially where sleep is delayed, morphine is invaluable; it has lately come much into vogue in the treatment of pneumonia, but its employment in malaria has been superseded by quinine, and it is less valuable in the treatment of mania, epilepsy, and chorea, than many other narcotics. Morphine depresses the medulla generally, including the respiratory centre, diminishes gaseous metabolism, and is used to arrest useless coughs, but its employment is contra-indicated in conditions where there is much expectoration. It is largely prescribed with expectorants in the coughs of phthisis and bronchitis. As morphine has a specific action on the alimentary canal, diminishing peristalsis, it is employed in the treatment of diarrhoea and colic, especially that due to lead. In peritonitis it is especially valuable, diminishing the pain, restlessness, and peristaltic movements; it should not be given, however, until a working diagnosis has been made. Morphine has few peripheral actions, it does not affect the heart or peripheral circulation, and so is invaluable in the insomnia of cardiac disease. It has no effect on the kidneys, but is better avoided in renal disease on account of its constipating effect. Secretions generally tend to diminish, but as morphine dilates skin vessels the excretion of sweat is increased. For this reason Dover's Powder forms a common remedy in the treatment of catarrhs. In diarrhoea, opium is preferred to morphine: for the relief of pain morphine is preferable. Morphine diminishes metabolism, and is commonly used in the treatment of diabetes (see Codeina). Tolerance to morphine is caused by the greater ability of the tissues to oxidise the alkaloid. Children are especially susceptible to morphine, and it must be prescribed for them with the very greatest care. The pure alkaloid, morphine, is employed only when oily solutions are required; in other cases, the soluble salts are more conveniently dispensed. For the preparation of a solution in oil (almond, olive, or liquid paraffin), the alkaloid is usually dissolved in ten times its weight of oleic acid, and the oleate so formed mixed with the oily vehicle. Ointments containing 2 to 5 per cent. of morphine may be similarly prepared. Oleinatum Morphinae contains 2 per cent. of the alkaloid; it is used with Oleinatum Hydrargyri to allay pain, or may itself be applied over painful areas, the oleic acid aiding absorption. Acute morphine poisoning has to be distinguished from certain cerebral conditions, intoxication, concussion, and haemorrhage; the equal pin-hole pupils which do not react to light form a valuable aid in diagnosis. Treatment of poisoning by morphine consists in washing out the stomach with dilute potassium permanganate solution two or three times at intervals of half an hour. Artificial respiration and inhalation of oxygen must be employed if necessary. Atropine, hot coffee, caffeine, or strychnine may be used to excite the respiratory centre.
Dose.—6 to 30 milligrams (1/10 to ½ grain).
PREPARATIONS.
- Aqua Morphinata.—MORPHINATED WATER, B.P.
- A saturated solution of the alkaloid, made by digesting pure morphine in chloroform water for seven days, at a temperature of 15.5°, with occasional agitation, and filtering from the undissolved morphine.
- Oleinatum Morphinae, B.P.C.—OLEINATE OF MORPHINE. Syn.—Oleatum Morphinae; Oleate of Morphine. 1 in 50.
- Readily absorbed by the skin, and is applied with a brush.
