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Intramuscular Injections.

     Intramuscular injections in no way differ essentially from subcutaneous.
Possibly absorption is slightly more energetic owing to a more active blood
and lymph circulation and less pain is occasioned, but the same destructive
and necrotic changes occur as in the subcutaneous proper. Kleine²² reports that
the tissues after subcutaneous injection, especially if intramuscular, look
severely damaged for a long time after injection; and Mariani ¹³made the same
observations in his rabbit experiments (intramuscular injections). These inju-
rious effects are hidden from view: necrosis does not reach the skin, so no ulcera-
tion follows. Paralysis, however, whether from thrombosis of blood vessels or
from direct destruction of nerve fibres, is more liable to occur after
intramuscular injections.

     Quinine solutions so dilute as 1 in 150 and containing sufficient Quinine
to be of any therapeutic value could not possibly be injected intramuscularly.
Such solutions would therefore have to be injected into the subcutaneous
connective tissue, as a Quinine infusion. The rapid and thorough absorption
that would follow such a Quinine infusion is more than counterbalanced by
the large ulcer that would infallibly result. Further, we have in the intra-
venous injection of Quinine a method which will give still greater Quinine
concentration in the blood without any of the special dangers of Quinine
infusions.

Intravenous Injections of Quinine.

     The intravenous method of administering Quinine was introduced by
Bacelli,⁴⁹ who used a solution containing Quinine hydrochloride, 1; sodium
chloride, .075; distilled water, 10 parts. This solution, however, the strength of
which is about 1 in 10, did not find favour, and certainly the serum compati-
bility experiments would lead one to expect the introduction of this concen-
trated solution intravenously to be attended with grave danger. The addition
of sodium chloride does not increase the compatibility of Quinine hydrochloride
with ox blood-serum.

     If a Quinine salt is to be safely introduced intravenously, it must be in a
dilution of 1 in 150 at least. Preferably the Quinine salt (e.g . about seven
grains of Quinine bi-hydrochloride) should be dissolved in two or three pints
of normal saline. In this dilution there is no danger of thrombosis or preci-
pitation: the toxins in the blood are also diluted and their elimination favoured
—this mode of administration being specially indicated in malignant types of
malaria. Such solutions have been infused intravenously with good effect in
cases of pernicious malaria. If there is any tendency to hæmoglobinuria, I