Summary
Highlights
Ergot alkaloids are discussed, including their use in reducing postpartum hemorrhage (Methyl Ergonovine) and their potent psychomimetic effects (LSD). Ergometrine is used as an oxytocic and during delivery. Ergotamine and dihydroergotamine salts are specific analgesics for migraine treatment. Ergotamine tartrate dosage is 2mg sublingually every 30 minutes up to 6mg/24 hours, not exceeding 10mg/week. Dihydroergotamine mesylate is more effective for migraine, with a parenteral dose of 1mg repeatable at 1-hour intervals up to 3mg.
Rauwolfia serpentina contains alkaloids like reserpine (principle alkaloid), rescinnamine, and deserpedine. Traditionally used as a hypnotic, sedative, antihypertensive, and for snake bites. Admine is used for cardiac arrhythmias. Reserpine is an antihypertensive and tranquilizer. Deserpedine is an antihypertensive with fewer side effects, but higher doses can cause mental depression. Usual daily doses range from 200-400mg for 1-3 weeks, with maintenance doses of 50-300mg.
Nux Vomica (Strychnos nux-vomica) contains strychnine and brucine. Strychnine is a highly toxic alkaloid that acts as a bitter, increasing appetite and stimulating peristalsis. It also supports the CNS and acts as a sex tonic, improving pulse and raising blood pressure in cardiac failure. Toxic doses cause tetanus-like convulsions and death. Brucine resembles strychnine but is less poisonous. Chemical tests for Nux Vomica include the stricnin test (purple with ammonium vanadate and sulfuric acid) and brucine test (yellow to orange with nitric acid).
Vinca (Catharanthus roseus), also known as Madagascar periwinkle, is ornamental and a source of important anticancer alkaloids: vinblastine and vincristine. Vinblastine is an antitumor alkaloid used for Hodgkin's disease, lymphocytic lymphoma, and other neoplasms. Vincristine is cytotoxic, treating childhood leukemia and used as an astringent and tonic for menorrhagia and hemorrhages. It's also used for sore throats, inflamed tonsils, and diabetes. Vinblastine sulfate is administered intravenously, with adult doses of 3.7mg/m2 and child doses of 2.5mg/m2, increasing weekly.
Physostigma venenosum (Calabar bean) contains physostigmine (eserine), a principal chemical constituent. It causes rapid pupil constriction, stimulates intestinal muscles, slows pulse, raises blood pressure, and depresses the CNS. It's used topically for ophthalmic purposes and as an antidote for anticholinergic poisoning. Imidazole alkaloids, like pilocarpine from Pilocarpus jaborandi, are heterocyclic aromatic compounds. Pilocarpine is used in pilocarpine HCl and pilocarpine nitrate as cholinergic drugs to treat glaucoma. Steroidal alkaloids, found in species like Veratrum viride, include jervine, germine, and veratramine. They are hypotensive, cardiac depressants, and sedatives, used for hypertension and as insecticides.
Alkaloidal amines lack heterocyclic nitrogen atoms. Examples include Colchicum autumnale (contains colchicine, an antigout agent, dosage 500-600.5mcg), Catha edulis (Khat, contains cathinone, a potent phenylalkylamine alkaloid), Lophophora williamsii (Peyote, contains mescaline, a hallucinogenic drug), and Ephedra sinica (Ma Huang, contains ephedrine, used as an adrenergic to treat hypotensive states and allergic disorders like bronchial asthma, and as a nasal decongestant. Doses are 25-50mg orally or parenterally 6-8 times/day).
Purine alkaloids are derivatives of a heterocyclic nucleus. Significant purine-containing plants include Cola nitida (cola, containing caffeine and theobromine, used as a stimulant in beverages), Coffee arabica (coffee, containing 1.5-2.2% caffeine, known for its stimulant effects and zero calories, decaffeinated coffee contains up to 0.08% caffeine), Paullinia cupana (guarana, a stimulating agent with caffeine and tannins), Ilex paraguariensis (mate or Paraguay tea, used as a laxative, diuretic, and diaphoretic).
Caffeine (1,3,7-trimethylxanthine) is found in coffee, tea, cacao, guarana, and mate. It acts as a stimulant (200mg dose). Theophylline (1,3-dimethylxanthine) from Camellia sinensis (tea) is a stimulant, astringent, and antiasthmatic (2.4mg/kg every 6 hours). Aminophylline, a derivative, is a diuretic, relieves asthma, and lowers venous pressure in heart failure. Theobromine (3,7-dimethylxanthine) from Theobroma cacao is a diuretic, smooth muscle relaxant, and stimulant (200mg three times daily). It is preferred over caffeine for treating cardiac edema and angina pectoris.