Pharmacological effects of methamphetamine and other stimulants via inhalation exposure

The effects of methamphetamine-HCl, methcathinone-HCl, cocaine and ephedrine on locomotor stimulation were compared between inhalation exposure and i.v. injection in mice. Methamphetamine-HCl was readily volatilized upon heating at 300 degrees C in a glass pipe with only trace amounts of amphetamine being produced. The ED50 dose (9.4 and 6.5 mumol/kg for inhalation exposure and i.v. injections, respectively) and biodisposition of methamphetamine-HCl were similar for both routes of administration. Methcathinone-HCl and cocaine were readily volatilized. Their dose response profiles also appeared similar for both routes of administration. Ephedrine did not appear to be easily volatilized and was only effective in stimulating locomotor activity after i.v. administration. These findings indicate that inhalation exposure to methamphetamine-HCl, cocaine and methcathinone possess similar pharmacological characteristics as the i.v. route of administration. In particular, this model may have implications in predicting the pharmacological activity of various stimulants via the inhalation route of administration.