This section is from the book "A Practitioner's Handbook Of Materia Medica And Therapeutics", by Thos. S. Blair. Also available from Amazon: A Practitioner's handbook of Materia Medica and Therapeutics.
Drosera, Sundew. This is a very valuable drug, but has well-defined limitations. Only preparations of the green plant are really active. The imported German tincture, the ec. tr., and the mother tincture are reliable. Drosera is antispasmodic, expectorant, and a respiratory sedative; highly useful in dry, irritable cough of a hoarse, resonant, and spasmodic nature. In my experience it is, generally speaking, the best agent we have in whooping cough. Spasmodic dry coughs generally are much relieved by it, and especially the cough of measles. Laryngeal phthisis is relieved somewhat by this agent. It combines nicely with other expectorant agents and with aconite and bryonia.
Dose, small and frequent doses are most useful. German tincture, 10 to 40 111. : ec. tr., I to 5 I.; @, 5 to 20 I.