ter method allows the THC to pass directly into the bloodstream, it is far less efficient than smoking. When swallowed, drugs pass through the stomach, intestine, and liver before entering the bloodstream, so they act slowly. This is especially true of the main active ingredient in marijuana. Because THC is barely soluble in water, the body absorbs only a small fraction of the available drug when it is swallowed.

The same is true of Marinol, which is simply THC in capsule form. Marijuana smoke, on the other hand, efficiently delivers THC into the bloodstream via the lungs. Inhaled THC takes effect quickly, allowing patients to use just enough to relieve their symptoms; it is not so easy to fine-tune the dose of oral medications. For this reason, pharmaceutical firms are investigating the use of smokeless inhalers and nasal sprays to deliver THC and possibly other cannabinoids.

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