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.
Apocynum Cannabinum, Canadian Hemp. In large doses apocynum is a harsh hydrogogue cathartic and emetic and should not be employed.
The fluidextract of the dried root is official, and may be employed in doses of 10 to 15 I, but candor compels the admission that it is a very uncertain preparation, its value depending upon how recent a root is employed. Those whose use of this drug has been limited to the fluidextract have missed its finer attributes and should try again. After large experience with the drug it has impressed me as a highly useful addition to our resources if employed in proper dose. In large dose the decoction is the safer preparation. It should be made from the fresh root and given carefully in teaspoonful doses. In moderate doses it has a dual influence. First, it is markedly diuretic, causing a flow of limpid urine without irritating the kidneys. In dropsy caused by non-action of the kidneys, and even in acute renal inflammation where dropsy occurs, as in post-scarlatinal nephritis, it is highly valuable, but remedies must be administered with it to overcome inflammation.
Second, it is a heart tonic, increasing the strength of the heart muscle and improving the arterial tonus. While similar in action to digitalis, it is not cumulative.
Its combined influence is such as to render it most useful in atonic conditions of the blood-vessels permitting exudation and causing dropsy. Any edema of the cellular tissues is rationally treated with this agent as well as effusions into nerve sheaths and joint tissues. This indicates its utility in sciatica, rheumatic neuralgia, and all localized effusions accompanied by asthenia. Dose (ec. tr., 1/4 to 5I , carefully increased, or @, 5 to 15 I, or fr, for short periods, 20 to 30 I). This is a drug that influences some persons much more readily than others, and it is best to commence with small doses in every case. Purgative effects supervening, it is time to reduce the dose. The distilled extract of fresh apocynum is of considerable service in doses of I or 2 teaspoonfuls.