228 CALOTROPIS-STANDARDISATION AND BIOLOGICAL ASSAY [Vol. XXII, Part III,
The tincture was injected as a continuous flow from the burette at the rate of
about 1 c.c. per minute until the heart stops beating as indicated by the blood
pressure record falling to the zero line. The time was noted at the beginning when
the injection was started and when the end point was reached by a stop watch.
Similarly the quantity of solution which was necessary to kill the cat was measured
from the burette. A typical graph in the cat assay is shown in Plate XVII.
A total of 14 cats were used in the assay of standard and the mean of the results
as calculated was 13.48±0.5619 (Table I).
It is suggested that any sample to be tested should be treated in the same way
and the mean of the results of not less than six cats should be determined for
comparison with the standard.
The potency of the sample being tested, expressed in relation to that of the
standard preparation, is determined by dividing the figure for the average lethal
dose of the standard preparation by the figure for the average lethal dose of the
sample being tested. It may also be expressed in per cent of the standard by multi-
plying the potency by hundred.
Pharmacology of Tincture Calotropis. The actions of Tincture calotropis
are very similar to that of gigantin. 0.05 to 0.1 c.c. per Kg. body-weight of the
tincture produces a sustained rise of blood pressure when given intra-venously to
anaesthetised dogs, even after sympatholysis by ergotoxine and paralysis of the
vagal terminals by atropinisation (Plate XIX). The volume of the spleen decreased
considerably corresponding to the rise of blood pressure. Myocardiogram experi-
ments in mammals showed that the systolic level of the ventricles and the auricles
were considerably increased with the diastole being normal or slightly deficient,
consequently the output per beat must have been more (Plate XVIII).
On respiration, the tincture decreases the rate but increses the depth (Plate XX).
Fixation of the Dose. After repeated trials with varying doses of the tincture,
it has been assessed that 0.3 c.c. per Kg. body-weight is a safe therapeutic oral
dose for canines. 0.6 c.c. per Kg. body-weight is slightly toxic. Retching and
emesis should be taken as the first sign of toxicity in the therapeutic administration
of the drug. On an average 2 to 12 minims has been fixed as the dose for canines
depending on the size and this repeated twice daily for about 20 days did not produce
any toxic symptoms.
DISCUSSION
The introduction of standards in the form of dry stable preparation makes
comparative methods possible, for every estimation of an unknown sample becomes
a comparison with a standard to see how much stronger or how much weaker it is.
Since the mixture of the leaf powder was made from different samples, its activity is
presumed to be equal to the mean activity of the sample of calotropis. It is possible
to establish an international standard from samples obtained from various parts
of the world and this may be taken up soon after the therapeutical usefulness has
been well established by clinical trials.
There is no evidence that cats vary in sensitiveness to the drug at different
times of the year and it is therefore unnecessary to make simultaneous tests of the
unknown and the standard. A determination of the average lethal dose per Kg. cat