Part 12

September 9: Found dead 9 a. m. _Autopsy_: Both lungs showed extensive pneumonia, with adhesions to pleura; pleuritis and pericarditis very marked; large amount of fibrous exudate in pleural cavity; pyloric end of stomach slightly congested; liver congested; other organs normal.

_Rabbit 393._ _Belgian._

Given 1 cc of 1 per cent caffein to each 100 grams, through stomach tube.

+---------+------------ Date. | Weight. | Treatment. ------------+---------+------------ | _Grams._| _cc._ Aug. 17 | 950 | 9.5 Aug. 18 | 910 | 9.0 Aug. 19 | 895 | 9.0 Aug. 20 | 910 | 9.0 Aug. 21 | 905 | 9.0 Aug. 22(1) | | Aug. 23 | 825 | 8.0 Aug. 24 | 870 | 8.5 Aug. 25 | 835 | 8.5 Aug. 26 | 780 | 8.0 Aug. 27 | 765 | 7.5 Aug. 28(1) | | Aug. 29 | 710 | Aug. 30(2) | | Aug. 31(1) | | ------------+---------+------------

(1) Not fed.

(2) Condition very poor; not fed.

September 1: Found dead. _Autopsy_: Lungs congested and adhering to the pleura; extensive inflammation of pleura; liver slightly enlarged and congested; mucosa of stomach and small intestines slightly congested; other organs normal.

_Rabbit 390._ _Belgian, male._

Given 1 cc of 1 per cent caffein to each 100 grams through stomach tube.

+---------+------------ Date. | Weight. | Treatment. ------------+---------+------------ | _Grams._| _cc._ Aug. 17 | 1,490 | 15.0 Aug. 18 | 1,370 | 14.0 Aug. 19 | 1,365 | 13.5 Aug. 20 | 1,340 | 13.5 Aug. 21 | 1,265 | 12.5 Aug. 22(1) | | Aug. 23 | 1,120 | 11.0 ------------+---------+------------

(1) Not fed.

August 24: Found dead 9 a. m. _Autopsy_: Heart and lungs appeared normal; abdominal viscera showed no apparent pathologic change other than coccidial infection of the liver and fullness of the blood vessels.

_Rabbit 392._ _Maltese, female._

Given 1 cc of 1 per cent caffein to each 100 grams through stomach tube.

+---------+----------- Date. | Weight. | Treatment. ------------+---------+----------- | _Grams._| _cc._ Aug. 17 | 1,265 | 12.5 Aug. 18 | 1,275 | 12.5 Aug. 19 | 1,240 | 12.5 Aug. 20 | 1,220 | 12.0 Aug. 21 | 1,245 | 12.5 Aug. 22(1) | | Aug. 23 | 1,180 | 12.0 Aug. 24 | 1,190 | 12.0 Aug. 25 | 1,155 | 11.5 Aug. 26 | 1,140 | 11.5 Aug. 27 | 1,140 | 11.5 Aug. 28(1) | | Aug. 29 | 1,115 | 11.0 Aug. 30 | 1,080 | 11.0 Aug. 31 | 1,020 | 10.0 Sept. 1 | 995 | 10.0 Sept. 2 | 930 | 9.0 ------------+---------+-----------

(1) Not fed.

Died at 3 p. m. September 2. _Autopsy_: The stomach and small intestines showed numerous small hemorrhagic spots; a thick coating of mucus surrounded the contents of the stomach; the other organs were apparently normal.

_Rabbit 403._ _Black._

Given 1 cc of 1 per cent caffein for each 100 grams.

+---------+----------- Date. | Weight. | Treatment. ------------+---------+----------- | _Grams._| _cc._ Aug. 20 | 1,640 | 16.5 Aug. 21 | 1,640 | 16.5 Aug. 22(1) | | Aug. 23 | 1,490 | 15.0 Aug. 24 | 1,515 | 15.0 Aug. 25 | 1,475 | 15.0 Aug. 26 | 1,390 | 14.0 Aug. 27 | 1,330 | 13.5 Aug. 28(1) | | Aug. 29 | 1,130 | 11.5 Aug. 30 | 1,055 | 10.5 ------------+---------+-----------

(1) Not fed.

August 31: Found dead at 3 p. m. _Autopsy_: Extensive gastroenteritis; liver enlarged and congested; spleen slightly congested; peritoneum thickened and congested; other organs normal.

_Rabbit 884._ _Black, female._

Given 1 cc of 1 per cent caffein for each 100 grams through stomach tube.

+---------+----------- Date. | Weight. | Treatment. ------------+---------+----------- | _Grams._| _cc._ Aug. 16 | 1,195 | 12.0 Aug. 17 | 1,205 | 12.0 Aug. 18 | 1,140 | 11.5 Aug. 19 | 1,180 | 12.0 Aug. 20 | 1,145 | 11.5 Aug. 21 | 1,145 | 11.5 Aug. 22(1) | | Aug. 23 | 1,005 | 10.0 Aug. 24 | 1,035 | 10.5 Aug. 25 | 990 | 10.0 Aug. 26 | 960 | 9.5 Aug. 27 | 955 | 9.5 Aug. 28(1) | | Aug. 29 | 870 | 9.0 Aug. 30(2) | 850 | 8.5 Aug. 31 | 810 | 8.0 Sept. 1 | 740 | 7.5 ------------+---------+-----------

(1) Not fed.

(2) Poor condition, mucus from rectum.

September 2: Found dead at 9 a. m. _Autopsy_: The mucosa of stomach showed numerous hemorrhagic spots; the first portion of the small intestines was slightly congested; the other organs were apparently normal in appearance.

_Rabbit 383._ _Belgian, female._

Given 1 cc of 1 per cent caffein for each 100 grams through stomach tube.

+---------+------------ Date. | Weight. | Treatment. -----------+---------+------------ | _Grams._| _cc._ Aug. 16 | 995 | 10.0 Aug. 17 | 1,005 | 10.0 Aug. 18 | 990 | 10.0 Aug. 19 | 895 | 9.0 Aug. 20 | 945 | 9.5 Aug. 21 | 965 | 9.5 Aug. 22(1) | | Aug. 23 | 875 | 9.0 Aug. 24 | 855 | 8.5 Aug. 25 | 850 | 8.5 Aug. 26 | 785 | 8.0 Aug. 27 | 710 | 7.0 -----------+---------+------------

(1) Not fed.

August 28: Found dead at 9 a. m. _Autopsy_: Lungs, heart, and spleen apparently normal; liver infected with coccidia; stomach apparently normal; walls of small intestines injected; colon marked congestion and hemorrhagic; kidneys hemorrhagic.

_Rabbit 387._ _Belgian male._

Given 1 cc of 1 per cent caffein for each 100 grams through stomach tube.

+---------+------------ Date. | Weight. | Treatment. -----------+---------+------------ | _Grams._| _cc._ Aug. 17 | 1,260 | 12.5 Aug. 18 | 1,340 | 13.0 Aug. 19 | 1,335 | 13.0 Aug. 20 | 1,300 | 13.0 Aug. 21 | 1,325 | 13.0 Aug. 22(1) | | Aug. 23 | 1,205 | 12.0 Aug. 24 | 1,200 | 12.0 Aug. 25 | 1,285 | 12.5 Aug. 26 | 1,185 | 12.0 Aug. 27 | 1,255 | 12.5 Aug. 28(1) | | Aug. 29 | 1,115 | 11.0 Aug. 30 | 1,135 | 11.5 Aug. 31 | 1,175 | 12.0 Sept. 1 | 1,050 | 10.5 Sept. 2 | 900 | 9.0 -----------+---------+------------

(1) Not fed.

September 3, found dead. _Autopsy_: Stomach and small intestines showed numerous hemorrhagic spots; thick coating of mucus surrounded the contents of the stomach; bladder was greatly distended with urine; the other organs were apparently normal.

_Rabbit 388._ _Belgian male._

Given 1 cc of 1 per cent caffein for each 100 grams, through stomach tube.

+---------+------------ Date. | Weight. | Treatment. -----------+---------+------------ | _Grams._| _cc._ Aug. 17 | 1,080 | 10.0 Aug. 18 | 1,115 | 11.0 Aug. 19 | 1,150 | 11.5 Aug. 20 | 1,130 | 11.5 Aug. 21 | 1,120 | 11.0 Aug. 22(1) | | Aug. 23 | 1,020 | 10.0 Aug. 24 | 985 | 10.0 Aug. 25 | 960 | 9.5 Aug. 26 | 900 | 9.0 Aug. 27 | 875 | 9.0 Aug. 28(1) | | -----------+---------+------------

(1) Not fed.

August 29, found dead 9 a. m. _Autopsy_: Heart and lungs normal; liver and kidneys engorged; stomach normal; intestines showed a catarrhal inflammation, though not severe; spleen normal; walls of colon somewhat injected.

_Rabbit 391._ _Belgian._

Given 1 cc of 1 per cent caffein to each 100 grams through stomach tube.

+--------+----------- Date. | Weight.|Treatment. -----------+--------+----------- |_Grams._| _cc._ Aug. 17 | 940 | 9.5 Aug. 18 | 950 | 9.5 Aug. 19 | 955 | 9.5 Aug. 20 | 935 | 9.5 Aug. 21 | 945 | 9.5 Aug. 22(1)| | Aug. 23 | 835 | 8.5 Aug. 24 | 805 | 8.0 Aug. 25 | 800 | 8.0 Aug. 26 | 765 | 7.5 Aug. 27(2)| 690 | 7.0 Aug. 28(1)| | Aug. 29 | 565 | 5.5 -----------+--------+-----------

(1) Not fed.

(2) Poor condition.

August 30, found dead 9 a. m. _Autopsy_: Heart injected; lungs normal; liver affected slightly with coccidiidea; stomach normal in appearance; small intestines normal, but colon considerably inflamed; kidneys slightly engorged; other organs normal.

_Rabbit 402._ _Black female._

Given 1 cc of 1 per cent caffein to each 100 grams.

+--------+----------- Date. | Weight.|Treatment. -----------+--------+----------- |_Grams._| _cc._ Aug. 20 | 2,030 | 20.0 Aug. 21 | 1,950 | 19.5 Aug. 22(1)| | Aug. 23 | 1,955 | 19.5 Aug. 24 | 1,905 | 19.0 Aug. 25 | 1,890 | 19.0 Aug. 26 | 1,780 | 18.0 Aug. 27 | 1,765 | 17.5 Aug. 28(1)| | Aug. 29 | 1,630 | 16.5 Aug. 30 | 1,540 | 15.5 Aug. 31 | 1,510 | 15.0 Sept. 1 | 1,425 | 14.0 -----------+--------+-----------

(1) Not fed.

September 2, found dead 9 a. m. _Autopsy_: The lungs were badly congested, the posterior lobe of the right lung showing hepatization; the liver was considerably enlarged and congested; the mucous membrane of the stomach and small intestines was congested and showed numerous hemorrhagic spots; the kidneys showed slight congestion; all other organs normal.

SERIES D.

The evidence brought forth in the preceding pages regarding cumulation of caffein naturally suggests the question whether or not the body acquires a tolerance for it. This question has already been answered in the affirmative by Gourewitch,(28) but owing to the method he used for the identification of caffein and the few experiments made his results are not conclusive. The experiments of series A, B, and C might be regarded as indicating that tolerance for caffein is not acquired by the rabbit. It was noticed, however, that the rabbit apparently does tolerate increasingly larger doses under certain conditions, as the following experiments show:

_Rabbit 223._ _Belgian hare, male._

October 22: Weight, 1,520 grams; 15 cc 2 per cent caffein injected subcutaneously at 2 p. m.

November 1: 10.30 a. m., weight, 1,510 grams; 17 cc 2 per cent caffein injected subcutaneously (225 mg per kilo), reflexes observed, but no tetanus.

November 4: 10.30 a. m., weight 1,535 grams; 19 cc 2 per cent caffein injected subcutaneously at 2.40 p. m.; 4.40 p. m., no symptoms.

November 8: Weight, 1,425 grams; 20 cc 2 per cent caffein (285 mg per kilo) injected at 11.45 p. m.; 5 p. m., no symptoms.

November 17: Weight, 1,325 grams; 22 cc 2 per cent caffein injected at 2.55 p. m. (329 mg per kilo), no symptoms.

November 18: Rabbit in good condition.

_Rabbit 224. Belgian hare, female. Diet, carrots._

October 18: Weight, 1,935 grams; 11.20 a. m., 15 cc 2 per cent caffein (155 mg per kilo) injected.

November 1: Weight, 1,780 grams; 20 cc 2 per cent caffein (224 mg per kilo) injected subcutaneously, reflexes increased, muscle tremors present, but no other symptoms.

November 4: Weight, 1,710 grams; 21.5 cc 2 per cent caffein (252 mg per kilo) injected.

November 8: Weight, 1,435 grams; 22.5 cc 2 per cent caffein or 314 mg per kilo injected at 11.40 p. m.; 5 a. m., no symptoms.

November 17: Weight, 1,340 grams; 24 cc 2 per cent caffein (358 mg per kilo) injected subcutaneously.

November 18: 9 a. m., rabbit died.

_Rabbit 226. Gray male. Diet, carrots._

October 28: Weight, 1,045 grams; 10 cc 2 per cent caffein injected subcutaneously at 1.50 p. m.; 4.30 p. m., tremors observed, but no other symptoms.

October 29: Rabbit in good condition.

November 1: Weight, 950 grams; 10.55 a. m., 11 cc 2 per cent caffein injected subcutaneously (231 mg per kilo).

November 4: Weight, 930 grams; 2.50 p. m., 12 cc 2 per cent caffein injected subcutaneously (258 mg caffein per kilo).

November 6: Weight, 945 grams; 11.45 a. m., 15 cc 2 per cent caffein (313 mg per kilo) injected subcutaneously.

November 17: Rabbit still alive; weight, 890 grams.

The results of these experiments indicate that when sufficient time is allowed between two successive injections, susceptibility to caffein is not increased. The rabbit, on the contrary, seems to acquire a tolerance for the drug, for the fourth dose was 15 per cent larger than the minimum fatal dose of caffein. This is in all probability due to the better elimination of caffein and its products of decomposition and to recovery from the deleterious effects of each dose, made possible by long intervals between injections.

The results of these experiments may be briefly summed up by stating that subminimum doses of caffein given to the rabbit daily or at intervals (not too long) do not produce any symptoms such as were observed in acute caffein intoxication, namely, increased reflexes and convulsions, or increased rate of respiration, thus showing that it is not cumulative. But evidence of undoubted summation of effect was adduced to show that if the administration of subminimum doses of caffein be continued daily for a period of 11 to 18 days the result is fatal. Tolerance, however, may be acquired, although to a limited extent only, provided sufficiently long intervals between injections are allowed to give time for repair of the injury done by the drug and to develop a mechanism for its better decomposition and elimination. Furthermore, the evidence just given indicates that the elimination of subminimum doses of caffein and its products of decomposition is probably accomplished within 24 hours or thereabouts. That the elimination of larger doses is not accomplished in this interval is made probable by the following experiment:

_Gray rabbit 455. Female. Diet, oats._

October 12: Weight, 1,185 grams; 3.30 p. m., 11.5 cc 2 of per cent caffein injected into the lumbar muscles; 3 p. m., reflexes increased.

October 13: 10 a. m., rabbit weighed 1,070 grams; no symptoms of caffein poisoning, reflexes normal; 10.30 a. m., 10 cc 2 per cent caffein injected into the lumbar muscles; 11.30 a. m., rabbit jumped off the table, had convulsions, and died.

EXPERIMENTS ON DOGS.

Having gained some information respecting the effects of repeated doses of caffein on rabbits, it was of interest to find out how carnivora reacted to the drug when similarly administered. A number of dogs were used for the purpose. Considerable variation in the mode of experimentation, as will appear later, was allowed.

Since the condition of the animal, its age, environment, or diet might be factors influencing toxicity, tests were made on full-grown and on young growing dogs whose food was varied. The subjects of the experiment were kept under observation for a few days to several weeks before the administration of caffein was begun, in order to determine whether or not any morbid condition existed, as well as to ascertain whether the new environment had any effect on these animals. Caffein was given chiefly by mouth, but the subcutaneous method was also employed during a portion of the experimental period in some dogs. The initial dose, which varied for different individuals, was maintained for a variable length of time. It was then progressively increased, in most cases until the death of the animal. With larger doses the intervals between successive injections were also increased.

SERIES A.

Six dogs were used in this series. Caffein was administered by mouth for periods of six days to five weeks. It was given daily or at intervals of two, and sometimes of three, days. In a few instances the drug was withheld for four or even for seven days, and its administration was resumed at the end of this time. The initial dose in these experiments varied approximately between 40 and 140 mg per kilo. The doses were then increased gradually, and thus the maximum resistance of the subject to caffein was tested. The diet consisted either exclusively of meat or largely of carbohydrates with a minimum amount of meat to give flavor to the food.

_Dog 11. Female._

Diet consisted of rice, 250 grams; cane sugar, 250 grams; meat, 50 grams; cracker meal, about 100 grams. Caffein was given by mouth daily or at intervals of one day, when the dose did not exceed 1.5 grams. Before the dose was increased to 2 grams, or approximately 0.213 gram caffein per kilo, an interval of two days was allowed. Symptoms were noticed the next day. An interval of two days was therefore allowed again at the end of which the same dose was repeated. It will be remarked that there were no symptoms this time, and the general condition of the dog seemed to be good. Two grams of caffein were, therefore, given daily during the next two days without any untoward effects; the dose was then increased to 2.5 grams. Even after this enormous quantity no symptoms were observed except slight tremors. When this dose was repeated 26 hours later, it proved fatal. No albumin or sugar was found in the urine, although the dog was fed on a very liberal carbohydrate diet. The following is a complete record of the experiment.

April 20: Urine acid, no albumin, no sugar.

April 21: Urine free from sugar.

April 22: Urine free from sugar. 1 gram caffein given in the afternoon.

April 23: 9 a. m., dog was very thirsty, drank a large quantity of water, urine did not reduce Fehling's solution.

April 24: 2.30 p. m., 1 gram caffein, no sugar in urine.

April 25: 1 gram caffein administered.

April 26: Weight, 10.6 kilos, urine collected in the morning, no sugar; 4.10 p. m., 1.5 grams caffein.

April 27: 1.5 grams caffein; 1.30 p. m., diet as before, no sugar in urine.

April 28: Weight, 10.2 kilos, no caffein, no sugar in urine.

April 30: Weight, 10.4 kilos, no sugar in urine; 4.20 p. m., 2 grams caffein.

May 1: Urine examined, sugar absent, weight 10 kilos, vomited, sick, tremors observed, drank 500 cc water at one time, appetite poor.

May 2: No caffein, drank 150 cc water.

May 3: Urine, no sugar, moderate quantity of albumen present; 12 noon, 2 grams caffein given by mouth, weight 10.3 kilos; 2 p. m., urine, sugar negative, condition of dog good, no symptoms of caffein intoxication.

May 4: 10 a. m., about 10 cc thick, dark-colored mucilaginous urine found in collecting bottle; albumin a little more than a trace, decidedly less than on May 3, no sugar, condition of dog pretty good except for slight muscular tremors; 4 p. m., 2 grams caffein by mouth (as usual).

May 5: Urine not examined, no symptoms; 4 p. m., 2 grams caffein.

May 6: Urine not examined; 2.30 p. m., 2.5 grams caffein given by mouth; 4 p. m., slight tremor, no other symptoms.

May 7: No examination of urine, no symptoms observed; 4 p. m., 2.5 grams caffein.

May 8: 9 a. m., found dead, urine collected since last dose of caffein was given did not contain any sugar or albumin, the amount of caffein fed to this dog was 18 grams in 18 days. _Autopsy_: Post-mortem examination showed marked enteritis with hemorrhagic spots on the mucosa; liver and kidneys congested and dark colored; lungs congested; thyroid gland was greatly enlarged and congested.

_Dog 28_.

April 30: Weight, 6.8 kilos; the diet consisted of 250 grams rice, 250 grams sugar, 100 grams cracker meal, and 100 grams of meat. On May 3 his weight was 7 kilos. He received 1 gram of caffein by mouth at 12 noon. At 2 p. m. he vomited and tremors were observed. The next day, May 4, tremors were still present though less pronounced. Examination of the urine for sugar and albumin was negative; on May 4, 1 gram caffein was given again and repeated on May 5. On this date his general condition was not good--dog had no appetite and refused to take caffein. As the dog lost 10 per cent of his weight he was put on a meat diet exclusively and the dose of caffein was reduced to 0.5 gram. He became sick after the second dose, and the administration of caffein was therefore discontinued. It was resumed after five days and the caffein was administered in increasing amounts, i. e., on May 18, 0.5 gram; May 19, 0.5; May 20, 1; May 21, 1 gram in two doses of 0.5 each, given at intervals of one hour; May 22, 1 gram. Dog became irritable, but no other symptoms were observed. The administration of caffein was omitted the next day. On the following day when the same dose of caffein was given there was again marked irritability and tremors. The experiment was therefore discontinued.

_Dog 22. Male bulldog._

June 24: Dog weighed 13.7 kilos. Diet consisted of meat exclusively; 1 gram caffein was given by mouth; diarrhea developed; no caffein was given for three days.

June 28: Dog weighed 13.6 kilos, 1.5 grams caffein given at 10 a. m.

June 30: 1.75 grams caffein administered.

July 2: Dog weighed 13.5 kilos; 2 grams caffein or 0.15 gram per kilo, caused well-marked thirst, but did not produce any other symptoms.

_Dog 20. Female_.

May 12: Weight, 7.7 kilos. Fed liberal carbohydrate diet, consisting of rice, 100 grams; sugar 100 grams; meat and cracker meal, a sufficient quantity to flavor the food.

May 14: Weight, 7.7 kilos. Examination of urine for albumin and sugar gave negative results. Urine was acid to litmus.

May 17: Weight, 7.4 kilos. Three hours after it was fed the dog received 0.5 gram caffein by mouth. The test of the urine the next day for sugar was negative, but a trace of albumin was present. It will be noticed that the doses were increased gradually and that symptoms were observed only after the fourth dose of 0.1 gram per kilo. Later meat was substituted for the carbohydrate diet and the administration of caffein was stopped for four days. At the end of this period 100 mg caffein per kilo was fed daily for five days, and the dose was then very gradually increased. Diarrhea occurred twice, but no other symptoms, the second attack having lasted a few days. The following is a complete record of the experiment:

May 19: 0.5 gram caffein 11.45 a. m.

May 20: 0.75 gram caffein 12.45 a. m.

May 21: 0.75 gram caffein 12 noon; no sugar, no albumin in urine.

May 22: 0.75 gram caffein; urine, same condition found; no symptoms.

May 23: Weight, 7.5 kilos; no caffein.

May 24: 0.75 gram caffein; tremors very marked.

May 25: No caffein.

May 26: 0.75 gram caffein.

May 27: 0.75 gram caffein.

May 28: 0.75 gram caffein.

May 29: 1 gram caffein in two doses of 0.75 and 0.25 gram.

May 30: No caffein.

May 31: No caffein; meat diet exclusively.

June 1: No caffein; meat diet exclusively.

June 2: No caffein; no sugar, no albumin in urine.

June 3: Weight, 7.6 kilos; 0.75 gram caffein; no sugar in urine.

June 4: Weight, 7.3 kilos; 0.75 gram caffein; no sugar in urine.

June 5: Weight, 7.5 kilos; 0.8 gram caffein; drank 500 cc water; ate 200 grams meat.

June 6: Weight, 7.4 kilos; 0.8 gram caffein; 500 cc urine; drank 500 cc water; ate 200 grams meat; no symptoms.

June 7: Weight, 7.7 kilos; 0.8 gram caffein 10 a. m.; 400 cc urine, 500 cc water, 200 grams meat.

June 8: Weight, 7.5 kilos; 0.9 gram caffein, 450 cc urine, 1 p. m.; 200 grams meat, 500 cc water.

June 9: Weight, 7.6 kilos; 0.9 gram caffein, 1 p. m.; 500 cc water, 200 grams meat and bone dust; diarrhea and restlessness all afternoon.

June 10: Weight, 7.6 kilos; 1 gram caffein, 500 cc water, 200 grams meat, 480 cc urine.

June 11: Weight, 8 kilos; 1 gram caffein, 470 cc urine, 500 cc water, 200 grams meat.

June 12: Weight, 7.8 kilos; 1 gram caffein, 710 cc urine, 500 cc water, 200 grams meat.