A process for supercritical fluid extraction of delta-9-tetrahydrocannabinol (delta-9-THC), delta-8-THC, cannabinoids or other medicinal value compounds from marijuana and other plants. Preferably, the extraction is carried out with a solvent of liquid carbon dioxide alone, or in combination with a solvent of ethanol, methanol, isopropanol, and other nonpolar/semipolar solvents at a temperature and pressure to maintain the solvents in a supercritical state. The extraction process is preferably carried out for a period of from 0 to 9 hours. The extraction process conditions result in different strengths of extracted marijuana and selective isolation of extracted compounds or mixtures of compounds. The processed marijuana leaves or other parts of the marijuana plant can be used in the manufacture of different strengths of cigarettes for the delivery of delta-9-THC or other related compounds, or as adjuvant drugs for antiinflammatory and analgesic treatment, especially for chronic and terminal pain, neuropathic pain symptoms in humans, and in animals. Further, spiking methods can be used to make cigarettes of different strengths containing delta-9-THC or other related compounds, either synthetic or natural. Placebo cigarettes can also be prepared with pharmacologically negligible quantities of an active compound. The isolated compounds, or mixture of isolated compounds and adjuvants, of the extracted compounds can be used for the treatment of the above mentioned symptoms, either through cigarettes or by other suitable delivery systems.