DIGITALIS

DIGITALIS

Synonyms

 Digitalis leaves, Foxglove leaves.

Biological Source-  Digitalis consists of dried leaves of Digitalis purpurea, family Scrophulariaceae, dried at a temperature below 60°C, immediately after Collecting the leaves. The leaves should contain not than 5 per cent of moisture.

Geographical Source – It is cultivated and collected in England, other parts of Europe, United States and India.

Collection and Cultivation

It is a biennial or perennial herb of about 1 to 2 meters.(in India, it is Cultivated in Kashmir aminary and Kishtawar) and also in Mungapoo and Nilgiri hills . It is propagated by seeds of the Elected strain, containing high glycosidalContent . It needs calcareous, acidic sandy, light soil with traces of manganese. Soil is sterilized by steam before sowing. It grows suitably in shady situation, luxuriantly at an altitude of 1600 to 3000 m. Favourable temperature range 20-30°C and rainfall -40 cm per annum. The seeds of digitalis are very small in size i.e. 100 seeds weigh 40 to 70 mg. They are mixed with fine sand and sown in the nursery beds in March/April. About 2.5 kg seeds are needed per hectare. The young seedlings are transplanted in September and November. The crop is manured properly and kept free of weeds. The plantation is done twice a year. In the first year, the plant bears rosette leaves and in the second year sessile leaves. The plant flowers in the month of April and is followed by the fruiting. If the plants are to be allowed to grow, the flowering tops are removed. Crop is protected from plant diseases, which otherwise lead to loss of potency of drug ..

The leaves are picked up in the afternoon during August and September in the first and the second year, when 2/3' of the flowers are fully developed. The basal leaves and the leaves at the pare collected at the end. The discoloured leaves are rejected. While collecting the leaves, dry weather is specifically selected. After plucking, the leaves are immediately brought to the drying entre and dried in vacuum driers. It curtails exposure of fresh leaves to the atmospheric conditions. The dried leaves (containing not more than 5 per cent of moisture) are packed into the air-tight containers, with suitable dehydrating agent….

The activity of the leaves is due to the glycoside. The presence of moisture and the enzymes (like digipurpuridase and Oxidase) cause deterioration of glycosides. If the leaves are dried above 60* C, potency is lost due to chemical degradation,

Uses

Digitalis glycosides have played significant role in medical Science for more than 200 years. most frequent use of digitalis is in the treatment of Congestive heart failure. Digitalis blocks sodium-potassium ATP-ase pump of the cardiac muscle so that intracellular concentration of sodium is increased. This leads to increase in calcium ions, released from sarcolemma and thereby brushing action of proteins viz. actin and myosin is enhanced. This is exhibited as more forceful contraction of myocardium, greater output per beat and Complete emptying of heart. Due to this, the delay circulation in Congestive heart failure is improved and the oedema is flushed out. Digitalis shortens the length of systole, thereby giving more time to rest between contractions.

Another major use of digitalis is slowing ventricular rate in atrial fibrillation, atrial flute supraventricular tachycardia and premature extra systoles. This is due to negative chronotropic  effect (slowing the heart rate) by directly suppressing the conduction of electric impulses at auriculo-ventricular node.

Digitalis has a cumulative effect in body and is slowly eliminated. Hence, dosage is import aspect. Generally, it is given by oral route except in emergency. As the digitalis dosage forms are prepared only from natural drug, variations in concentration and thereby exact content in different brands is possible. Hence, during therapy, physician relies on only one brand at a time.