Investigation of inhalatory delivery (i.e. aerosol)

For inhalation tests two formulations have been prepared:

1. Solution for modified e-cigarette device for aerosol administration: 50% propylene glycol,

30% glycerin, 2:1 propylene glycol/glycerol solution with 0.1-0.5% Mitragyna alkaloids and 0.1-0.5%

cannabinoids and distilled water q.s. (used in mice). Measurements of the aerosol droplets showed

to be less than 5.0 μm in diameter suggesting that they were sufficiently small to penetrate deeply

into the lungs. Inhalation exposure to aerosolized Mitragyna alkaloids and cannabinoids at very low

concentrations in mice elicited antiinflammatory and antinociceptive effects otherwise less

effective with each single extract.

2. Pressurized spray preparation: 2:1 propylene glycol/glycerol solution with 0.1-0.5%

Mitragyna alkaloids and 0.1-0.5% cannabinoids in the formulation with polysorbate 80, sorbitan

laurate, hydroxypropylcellulose, citric acid and sodium citrate, benzalkonium chloride and distilled

water q.s. (to be used in human tests).

An in vivo evaluation of the anti-inflammatory and anti-nociceptive activity of purified extracts of

inhalatory delivery (aerosol) of Mitragyna speciosa and Cannabis in combination at low

concentrations was performed on mice, in similar manner to the evaluation of the antiinflammatory

acrivityactivity described above.

The habituation of mice was carried out in a transparent cage (22 cm × 16 cm × 13 cm), that also

served as observation chamber. Another plexiglass cage was turned upside down and placed over

the first cage, in order to avoid any leaks of aerosol.

Albino Balb/C mice (25-32g) of both sexes were used. Animals were fasted for 24 h before

treatment. The test was performed using a subplantar carrageenan-induced paw oedema, as

described in the literature (Morris 2003). The inhalation exerted anti-inflammatory and antinociceptive

effects. In particular, it reduced the carragenan-induced licking/biting behaviour in a

manner that was dependent on the volume of nebulized solution used in the device for its release

and on the time of exposure to low concentration alkaloids and cannabinoids solution. Statistical

analyses were performed using one-way ANOVA followed by the Newman Keulse test. The aerosol

formulations (concentration: 0.1-0.5% of alkaloids and 0.1-0.5% of cannabinoids) have been

nebulized in the cage for 30 60 sec just before a subplantar carrageenan injection