Table 1. Escalating Dosing Regimen Used in the Current Study.
| Day 1 | Day 2 | Day 3 | Day 4 | Day 5 | Day 6 | Day 7 | |
| Injection 1 | 0.1 | 0.4 | 0.7 | 1.0 | 1.3 | 1.6 | Off |
| Injection 2 | 0.2 | 0.5 | 0.8 | 1.1 | 1.4 | 1.7 | |
| Injection 3 | 0.3 | 0.6 | 0.9 | 1.2 | 1.5 | 1.8 | |
| Day 8 | Day 9 | Day 10 | Day 11 | Day 12 | Day 13 | Day 14 | |
| Injection 1 | 1.9 | 2.2 | 2.5 | 2.8 | 3.1 | 3.4 | Off |
| Injection 2 | 2.0 | 2.3 | 2.6 | 2.9 | 3.2 | 3.5 | |
| Injection 3 | 2.1 | 2.4 | 2.7 | 3.0 | 3.3 | 3.6 | |
| Day 15 | Day 16 | Day 17 | Day 18 | Day 19 | Day 20 | Day 21 | |
| Injection 1 | 3.7 | 4.0 | 6.0 | 6.0 | 6.0 | 6.0 | Off |
| Injection 2 | 3.8 | 4.0 | 6.0 | 6.0 | 6.0 | 6.0 | |
| Injection 3 | 3.9 | 4.0 | 6.0 | 6.0 | 6.0 | 6.0 | |
| Injection 4 | 6.0 | 6.0 | 6.0 | 6.0 | |||
| Day 22 | Day 23 | ||||||
| Injection 1 | 6.0 | 6.0 | |||||
| Injection 2 | 6.0 | 6.0 | |||||
| Injection 3 | 6.0 | ||||||
| Injection 4 | 6.0 |
Values represent dose of methamphetamine hydrochloride (free-base weight; mg/kg) administered to rats across the 23-day regimen. During the first 3 weeks of the dosing regimen, injections were given every 4 h. Injections during the last week of the dosing regimen were given every 3 h.