I don’t want to derail this thread, but I disagree with this comment. Pharmacokinetics is defined as the time course of ADME (absorption, distribution, metabolism, and excretion). Different routes of administration DO affect the rates of absorption into the systemic circulation. For example, the stratum corneum in your skin is an effective barrier against extremely lipophilic or hydrophilic compounds; these compounds will be only slowly absorbed. Inhalation only involves simple dissolution into the alveolar fluid (I think…). The GI tract provides numerous barriers to absorption, the unstirred water layer being the rate limiting step for lipophilic compounds like THC. Thus, in this particular case, the rate of absorption for THC will be lower when administered orally relative to that of inhalation.
I do agree wholeheartedly that the bioavailability of THC is lower when subjected to first pass metabolism by the liver.
In any case, I don’t think this little bit of pedantry really affects the conclusions we reach from the OP’s question.