2. DIGITALIS
Synonyms: Foxglove leaves, digitalis leaves
Biological source:It is obtained from dried leaves of
Digitalispupurea
Family: Scrophulariaceae.
Habitat: It is a biennial herb which is grown in
England and also cultivated in India, Europe and USA.
Cultivation/Collection:It is propagated by seeds.
• It requires calcareous, acidic, sandy soil for growth.
Seeds are very small in size i.e. 100 seeds weigh 40 to
70 mg.
3. .
Seeds are mixed with fine sand and sown in nursery beds
in march/april.
Young seedlings are transplanted in sep/november.
Crop is manured and kept free from weeds.
Plantation done twice a year.
Plant flowers in the month of april and is followed by
fruiting.
6. .
In the first year plant bears rosette leaves and in
second year sessile leaves. Leaves collected in second
year in the afternoon during august and September
when 2/3rd of flowers are fully developed.
• Discolored leaves are rejected.
• After collection leaves are immediately brought to
drying centre and dried in vaccum dryer at a temp.
below 60 C till the moisture is not more than 5%.Dried
leaves are packed in air tight container with suitable
dehydrating agent. If the leaves are dried above 60 C
the potency is lost due to chemical degradation.
7. .
Activity of the leaves is due to glycosides.
Presence of moisture and enzyme i.e. Digipurpuridase
and oxidase cause deterioration.
Macroscopy:
Colour: Dark greyish green
Odour: Odourless
Taste: Distinctly bitter
Size: length-10 to 30 cmWidth - 4 to 10 cm
Shape: Ovate, lanceolate, petiolate
8. .
Chemical constituents:
Digitalis contain 0.2 to 0.45% of both primary and
secondary glycosides.
Primary glycosides- Purpurea glycosides A and B.
glucogetaloxin and Secondary are - digitoxin, gitoxin and
getaloxin.
Primary glycosides are less stable and less significant than
secondary glycosides.
Purpurea glycosides A and B constitute the principle active
constituent of the fresh leaves.
9. uses
Uses It's used in the treatment of congestive heart
failure.
Mechanism of action
block the Na-K+ ATPase pump of cardiac muscle
Increase the intracellular sodium level
Increase in calcium ions
Result in forceful contraction of myocardium
10. ,
Greater output per beat
Complete emptying of heart delayed circulation
improved
11. .
2. It increase excitability of cardiac muscle and
produce more powerful contractions.
3. The improvement through kidney results in diuresis
and loss of oedema.
4. It is effective in congestive heart failure to increase
cardiac output and to relieve venous congestion, hence
it is used as cardio tonic.
5. The major disadvantage of digitalis is that it has
'cumulative effect' so administration of drug should be
under strict medical supervision.
12.
13. Toxicity
Depending on the species, the digitalis plant may
contain several deadly physiological and chemically
related cardiac and steroidal glycosides. Thus, the
digitalis plants have earned several, more sinister,
names: dead man's bells and witch's gloves. The toxins
can be absorbed via the skin or ingestion.
14. ,
Digitalis intoxication, known as digitalism, results from an
overdose of digitalis and can cause gastrointestinal, cardiac
and neurological effects.
The former include appetite loss, nausea, vomiting
and diarrhoea;
the cardiac symptoms include both tachycardia,
and bradycardia (either of which, if severe enough, can result
in syncope); and
the nerological effects include fatigue, delirium, and
rarely xanthopsia (jaundiced or yellow vision).
Other oculotoxic effects of digitalis include generalized blurry
vision, as well as the appearance of blurred outlines
('halos'). Other things mentioned are dilated pupils, drooling,
weakness, collapse, seizures, and even death.
15. .
Digitalis poisoning can cause indirect inhibition of
the atrioventricular node via a direct effect on the vagal
nucleus. This results in bradycardia (decreased heart rate)
or if severe enough, heart block.
The direct effect of cardiac glycosides on heart muscle cells
is to increase contraction of the cells, both in force and
frequency, tending to produce tachycardia (increased heart
rate), depending on the dose, the condition of one's heart,
and the prevailing chemistry of the blood (specifically any
of: low potassium, high calcium and low magnesium).
Electrical cardioversion (to "shock" the heart) is generally
not indicated in ventricular fibrillation in digitalis toxicity,
as it can make the rhythm disturbance more complicated
or sustained.
16. .
Furthermore, the classic drug of choice for ventricular
fibrillation in emergency setting, amiodarone, can
worsen the dysrhythmia caused by digitalis, therefore,
the second-choice drug lidocaine is more commonly
used.
Mild toxicity is treated by stopping the medication and
general supportive measures;
severe toxicity is treated with anti-digoxin antibody
fragments.
17. . The entire plant is toxic (including the roots and
seeds).
Mortality is rare, but case reports do exist. Most plant
exposures occur in children younger than six years and
are usually unintentional and without associated
significant toxicity.
More serious toxicity occurs with intentional
ingestion by adolescents and adults
