The AD50 for morphine by different routes of administration in mice rendered tolerant to morphine by pellet implantation
| Treatment | Apparent AD50 of Morphine (95% Confidence Limits) | ||
|---|---|---|---|
| s.c. (μmol/kg) | i.c.v. (nmol/mouse) | i.t. (nmol/mouse) | |
| Placebo | 10.5 (5.3–20.6) | 5.5 (2.8–11.0) | 0.9 (0.5–1.7) |
| Morphine | 80.0 (45.0–141.0) | 8.5 (5.4–13.3) | 1.1 (0.8–1.6) |