20

B.—Immediately after food.

       The minimum-lethal dose per kilogramme when Quinine is given with food
is larger (about .5 gramme) than when given after a fast of 24 hours (about .45
gramme). We must conclude, therefore, that, so far at least as guinea-pigs are
concerned, absorption is more energetic when the animal is fasting. The same
most probably holds for man, the reason for the greater total elimination of
Quinine in the urine when Quinine is administered with food being a
slower and more gradual absorption of Quinine, with a consequent smaller
amount of cleavage of the alkaloid. When Quinine is administered during a
fast, there is probably an early abrupt and energetic absorption with pro-
portionate cleavage of the alkaloid. Rapid and energetic absorption is most
likely best obtained, therefore, by giving a soluble Quinine salt during a fast;
a slow, gradual but persistent action by giving insoluble salts of Quinine with
meals.

       Soluble salts of Quinine, if given in capsules, are apt to form temporarily
local concentrated solutions in the stomach and cause gastric discomfort and
even serious injury to that organ. It is also worth noting that, where the
ordinary salts of Quinine cause gastric irritation, the difficulty may be overcome
by administering one of the insoluble salts, e.g., the tannate, which is
practically insoluble till it reaches the intestine.

       5. Carbon dioxide (CO₂).—It has been shown by Kerner² that Quinine and
its salts* are much more soluble in ærated than in ordinary water. When
Quinine sulphate is dissolved in ærated water, no immediate precipitate is
produced by adding an equivalent amount of sodium carbonate; and, no
precipitate is produced by adding a concentrated Quinine solution to a dilute
solution of sodium bicarbonate in ærated water. These results suggested to

* NOTE.—Water saturated with carbonic acid dissolves Quinine sulphate freely.