Camphor (camphora, ae) is a stearopten, C9H16CO, which is chemically a ketone. It is made synthetically or is obtained by boiling the twigs and wood of Cinnamomum camphora (Fam. Lauraceae) with water, and condensing the distillate. The camphor tree is an evergreen of Japan and China, and has been introduced into the southern United States for ornamental purposes. Camphor is a volatile, inflammable, gummy substance, freely soluble in alcohol, ether, chloroform, and the fixed and volatile oils. In water it is soluble to the extent of about 8 parts in 1000, just enough to impart to the water a strong odor and taste. Though of a gummy nature, it may be powdered on the addition of a little alcohol or chloroform. Its mixtures with menthol, salol, chloral hydrate, thymol, and some other solids become liquid without apparently undergoing any chemic change. Preparations and Doses. -

Camphor, 2 grains (0.13 gm.).

Water, 0.8 per cent., 2 drams (8 c.c.).

Spirit, 10 per cent., 20 minims (1.3 c.c.).

Liniment (Camphorated Oil), 20 Per Cent

for external use. Camphor is also an ingredient of soap liniment, chloroform liniment, menthol-camphor, N. F. (menthol, 1; camphor, 1), chloral-camphor, N. F. (chloral hydrate, 1; camphor, 1), rhinitis tablets (see Belladonna), and various diarrhea remedies. Among these latter, two well-known ones are "Sun Cholera Drops" and "Squibb's Diarrhea Mixture." (See Anti-diarrheics.) An allied product is monobromated camphor (camphora mono-bromata), i. e., camphor in which one H has been replaced by bromine, C9H15BrCO. It is used for its bromine as a nerve sedative, dose, 2 grains (0.13 gm.).

Pharmacologic Action

Micro-Organisms And Insects

Camphor is moderately antiseptic. Its odor is disliked by insects, and it is used to drive away moths, mosquitos, etc.

Skin

If a strong preparation is rubbed into the skin or kept in contact with it for some time, it is counterirritant, exerting a "rubefacient" effect, i. e., it irritates the skin and dilates the skin vessels so that the part becomes red and warm. It should be covered with a piece of flannel or oiled silk to prevent evaporation. If, however, camphor dissolved in alcohol, as in spirit of camphor, is applied and allowed to evaporate, it has just the opposite effect, that is, blanches and cools the part.

Mucous Membranes

Camphor irritates mucous membranes and causes them to contract, and for this and its antiseptic property is considered useful in nasal therapeutics.

Alimentary Tract

The solid gum-camphor is chewed with pleasure by some people, but to most has a biting taste and is nauseating. In solution it has a strongly carminative action, and in strong doses may be so irritant as to cause vomiting. In the intestines it is believed to check secretion, though this point is not definitely established. It is said also to be antiseptic in the intestines, because in a series of tests it was shown to decrease the ethereal sulphates of the urine.

Absorption

It is absorbed readily from stomach and intestines, and, if used hypodermatically, from the tissues. When used hypodermatically it is irritant.

Circulatory Organs

Before Absorption

When the drug is swallowed in strong enough solution to have marked local action on the mouth, there is at once a moderate acceleration of the rate of the heart corresponding with that obtained from other members of the volatile oil series. It is solely a reflex effect.

After Absorption

Any good effects upon the circulation are extremely problematic, the ones reported being mild stimulation of the heart muscle and mild stimulation of the vagus and vasoconstrictor centers. In normal animals the rate and force of the heart continue about the same, and the total output of the heart is either not affected at all or is slightly increased. There is also a dilatation of the skin vessels, but this does not essentially affect general arterial pressure.

The stimulation of the vasoconstrictor center is an uncertain quantity, for at times there is no stimulation; while when there is stimulation, it may be intermittent, so that periods of lowered arterial pressure alternate with periods of raised arterial pressure. There may be slowing of the heart and a fall in blood-pressure. Hence, as a vasoconstrictor, camphor ranks low. In fact, Likhatcheva reports dilatation of the peripheral and coronary arteries from perfusion with solutions of 1: 5000 to 1: 2500.

Fig. 29.

Fig. 29. - Camphor in oil, 20 mg. per kilo intravenously. Little effect on auricle and ventricle. Fall in arterial pressure from 91 to 78. Pulse somewhat slowed. (Tracing made by Dr. C. C. Lieb.)

Cushny says of it, "in man and animals the heart is sometimes slowed, but is generally little affected in either strength or rate," and, "the slight dilatation of the vessels (of the skin) is the only change in the circulation, unless quantities sufficient to cause convulsions are injected." Gottlieb and Meyer (1910) agree with Cushny so far as normal laboratory animals are concerned. "Thus," they say, "camphor cannot ordinarily be considered a circulatory stimulant. But in the conditions of circulatory failure, where stimulus production in the heart threatens to fail, camphor is undoubtedly to be considered a heart stimulant. For in perfusion camphor will overcome the fibrillation of the auricle which is caused by chloroform and other poisons, and even that from electric stimulation, and it will prevent the excessive slowing and weakening brought on by chloral hydrate." Heinz says practically the same.

In one case of septicemia in which the author injected 5 grains (0.3 gm.) of camphor in oil hypodermatically three times a day for two days there occurred, on three occasions, for about two hours after the dose, a distinct weakening of the heart, with depression of the respiration and Cheyne-Stokes breathing.