Table 1.
A final injection volume of 5 mL was taken being fixed for all combinations tested.
| Akis (final dilution in brackets) | Vehicle | Anaesthetic (final dilution in brackets) |
|---|---|---|
| 25 mg/mL, 1 mL (5 mg/mL) |
Normal saline 3 mL | Lidocaine 1% 1 mL (0.2%) |
| Normal saline 2 mL | Lidocaine 1% 2 mL (0.4%) | |
| Water 3 mL | Lidocaine 1% 1 mL (0.2%) | |
| Water 2 mL | Lidocaine 1% 2 mL (0.4%) | |
| Bicarbonate 3 mL | Lidocaine 1% 1 mL (0.2%) | |
| Bicarbonate 2 mL | Lidocaine 1% 2 mL (0.4%) | |
| Normal saline 3 mL | Lidocaine 2% 1 mL (0.4%) | |
| Normal saline 2 mL | Lidocaine 2% 2 mL (0.8%) | |
| Water 3 mL | Lidocaine 2% 1 mL (0.4%) | |
| Water 2 mL | Lidocaine 2% 2 mL (0.8%) | |
| Bicarbonate 3 mL | Lidocaine 2% 1 mL (0.4%) | |
| Bicarbonate 2 mL | Lidocaine 2% 2 mL (0.8%) | |
|
| ||
| 50 mg/mL, 1 mL (10 mg/mL) |
Normal saline 3 mL | Lidocaine 1% 1 mL (0.2%) |
| Normal saline 2 mL | Lidocaine 1% 2 mL (0.4%) | |
| Water 3 mL | Lidocaine 1% 1 mL (0.2%) | |
| Water 2 mL | Lidocaine 1% 2 mL (0.4%) | |
| Bicarbonate 3 mL | Lidocaine 1% 1 mL (0.2%) | |
| Bicarbonate 2 mL | Lidocaine 1% 2 mL (0.4%) | |
| Normal saline 3 mL | Lidocaine 2% 1 mL (0.4%) | |
| Normal saline 2 mL | Lidocaine 2% 2 mL (0.8%) | |
| Water 3 mL | Lidocaine 2% 1 mL (0.4%) | |
| Water 2 mL | Lidocaine 2% 2 mL (0.8%) | |
| Bicarbonate 3 mL | Lidocaine 2% 1 mL (0.4%) | |
| Bicarbonate 2 mL | Lidocaine 2% 2 mL (0.8%) | |
|
| ||
| 25 mg/mL, 1 mL (5 mg/mL) |
Normal saline 3 mL | Mepivacaine 1% 1 mL (0.2%)∗ |
| Normal saline 2 mL | Mepivacaine 1% 2 mL (0.4%)∗ | |
| Water 3 mL | Mepivacaine 1% 1 mL (0.2%)∗ | |
| Water 2 mL | Mepivacaine 1% 2 mL (0.4%)∗ | |
| Bicarbonate 3 mL | Mepivacaine 1% 1 mL (0.2%)∗ | |
| Bicarbonate 2 mL | Mepivacaine 1% 2 mL (0.4%)∗ | |
| Normal saline 3 mL | Mepivacaine 2% 1 mL (0.4%) | |
| Normal saline 2 mL | Mepivacaine 2% 2 mL (0.8%) | |
| Water 3 mL | Mepivacaine 2% 1 mL (0.4%) | |
| Water 2 mL | Mepivacaine 2% 2 mL (0.8%) | |
| Bicarbonate 3 mL | Mepivacaine 2% 1 mL (0.4%) | |
| Bicarbonate 2 mL | Mepivacaine 2% 2 mL (0.8%) | |
|
| ||
| 50 mg/mL, 1 mL (10 mg/mL) |
Normal saline 3 mL | Mepivacaine 1% 1 mL (0.2%)∗ |
| Normal saline 2 mL | Mepivacaine 1% 2 mL (0.4%)∗ | |
| Water 3 mL | Mepivacaine 1% 1 mL (0.2%)∗ | |
| Water 2 mL | Mepivacaine 1% 2 mL (0.4%)∗ | |
| Bicarbonate 3 mL | Mepivacaine 1% 1 mL (0.2%)∗ | |
| Bicarbonate 2 mL | Mepivacaine 1% 2 mL (0.4%)∗ | |
| Normal saline 3 mL | Mepivacaine 2% 1 mL (0.4%) | |
| Normal saline 2 mL | Mepivacaine 2% 2 mL (0.8%) | |
| Water 3 mL | Mepivacaine 2% 1 mL (0.4%) | |
| Water 2 mL | Mepivacaine 2% 2 mL (0.8%) | |
| Bicarbonate 3 mL | Mepivacaine 2% 1 mL (0.4%) | |
| Bicarbonate 2 mL | Mepivacaine 2% 2 mL (0.8%) | |
|
| ||
| 25 mg/mL, 1 mL (5 mg/mL) |
Normal saline 3 mL | Bupivacaine 0.25% 1 mL (0.05%)∗ |
| Normal saline 2 mL | Bupivacaine 0.25% 2 mL (0.1%)∗ | |
| Water 3 mL | Bupivacaine 0.25% 1 mL (0.05%)∗ | |
| Water 2 mL | Bupivacaine 0.25% 2 mL (0.1%)∗ | |
| Bicarbonate 3 mL | Bupivacaine 0.25% 1 mL (0.05%)∗ | |
| Bicarbonate 2 mL | Bupivacaine 0.25% 2 mL (0.1%)∗ | |
| Normal saline 3 mL | Bupivacaine 0.5% 1 mL (0.1%) | |
| Normal saline 2 mL | Bupivacaine 0.5% 2 mL (0.2%) | |
| Water 3 mL | Bupivacaine 0.5% 1 mL (0.1%) | |
| Water 2 mL | Bupivacaine 0.5% 2 mL (0.2%) | |
| Bicarbonate 3 mL | Bupivacaine 0.5% 1 mL (0.1%) | |
| Bicarbonate 2 mL | Bupivacaine 0.5% 2 mL (0.2%) | |
|
| ||
| 50 mg/mL, 1 mL (10 mg/mL) |
Normal saline 3 mL | Bupivacaine 0.25% 1 mL (0.05%)∗ |
| Normal saline 2 mL | Bupivacaine 0.25% 2 mL (0.1%)∗ | |
| Water 3 mL | Bupivacaine 0.25% 1 mL (0.05%)∗ | |
| Water 2 mL | Bupivacaine 0.25% 2 mL (0.1%)∗ | |
| Bicarbonate 3 mL | Bupivacaine 0.25% 1 mL (0.05%)∗ | |
| Bicarbonate 2 mL | Bupivacaine 0.25% 2 mL (0.1%)∗ | |
| Normal saline 3 mL | Bupivacaine 0.5% 1 mL (0.1%) | |
| Normal saline 2 mL | Bupivacaine 0.5% 2 mL (0.2%) | |
| Water 3 mL | Bupivacaine 0.5% 1 mL (0.1%) | |
| Water 2 mL | Bupivacaine 0.5% 2 mL (0.2%) | |
| Bicarbonate 3 mL | Bupivacaine 0.5% 1 mL (0.1%) | |
| Bicarbonate 2 mL | Bupivacaine 0.5% 2 mL (0.2%) | |
|
| ||
| 25 mg/mL, 1 mL (5 mg/mL) |
Normal saline 3 mL | Levobupivacaine 0.25% 1 mL (0.05%) |
| Normal saline 2 mL | Levobupivacaine 0.25% 2 mL (0.1%) | |
| Water 3 mL | Levobupivacaine 0.25% 1 mL (0.05%) | |
| Water 2 mL | Levobupivacaine 0.25% 2 mL (0.1%) | |
| Bicarbonate 3 mL | Levobupivacaine 0.25% 1 mL (0.05%) | |
| Bicarbonate 2 mL | Levobupivacaine 0.25% 2 mL (0.1%) | |
| Normal saline 3 mL | Levobupivacaine 0.75% 1 mL (0.15%) | |
| Normal saline 2 mL | Levobupivacaine 0.75% 2 mL (0.3%) | |
| Water 3 mL | Levobupivacaine 0.75% 1 mL (0.15%) | |
| Water 2 mL | Levobupivacaine 0.75% 2 mL (0.3%) | |
| Bicarbonate 3 mL | Levobupivacaine 0.75% 1 mL (0.15%) | |
| Bicarbonate 2 mL | Levobupivacaine 0.75% 2 mL (0.3%) | |
|
| ||
| 50 mg/mL, 1 mL (10 mg/mL) |
Normal saline 3 mL | Levobupivacaine 0.25% 1 mL (0.05%) |
| Normal saline 2 mL | Levobupivacaine 0.25% 2 mL (0.1%) | |
| Water 3 mL | Levobupivacaine 0.25% 1 mL (0.05%) | |
| Water 2 mL | Levobupivacaine 0.25% 2 mL (0.1%) | |
| Bicarbonate 3 mL | Levobupivacaine 0.25% 1 mL (0.05%) | |
| Bicarbonate 2 mL | Levobupivacaine 0.25% 2 mL (0.1%) | |
| Normal saline 3 mL | Levobupivacaine 0.75% 1 mL (0.15%) | |
| Normal saline 2 mL | Levobupivacaine 0.75% 2 mL (0.3%) | |
| Water 3 mL | Levobupivacaine 0.75% 1 mL (0.15%) | |
| Water 2 mL | Levobupivacaine 0.75% 2 mL (0.3%) | |
| Bicarbonate 3 mL | Levobupivacaine 0.75% 1 mL (0.15%) | |
| Bicarbonate 2 mL | Levobupivacaine 0.75% 2 mL (0.3%) | |
|
| ||
| 25 mg/mL, 1 mL (5 mg/mL) |
Normal saline 3 mL | Ropivacaine 0.2% 1 mL (0.04%) |
| Normal saline 2 mL | Ropivacaine 0.2% 2 mL (0.08%) | |
| Water 3 mL | Ropivacaine 0.2% 1 mL (0.04%) | |
| Water 2 mL | Ropivacaine 0.2% 2 mL (0.08%) | |
| Bicarbonate 3 mL | Ropivacaine 0.2% 1 mL (0.04%) | |
| Bicarbonate 2 mL | Ropivacaine 0.2% 2 mL (0.08%) | |
| Normal saline 3 mL | Ropivacaine 1% 1 mL (0.2%) | |
| Normal saline 2 mL | Ropivacaine 1% 2 mL (0.4%) | |
| Water 3 mL | Ropivacaine 1% 1 mL (0.2%) | |
| Water 2 mL | Ropivacaine 1% 2 mL (0.4%) | |
| Bicarbonate 3 mL | Ropivacaine 1% 1 mL (0.2%) | |
| Bicarbonate 2 mL | Ropivacaine 1% 2 mL (0.4%) | |
|
| ||
| 50 mg/mL, 1 mL (10 mg/mL) |
Normal saline 3 mL | Ropivacaine 0.2% 1 mL (0.04%) |
| Normal saline 2 mL | Ropivacaine 0.2% 2 mL (0.08%) | |
| Water 3 mL | Ropivacaine 0.2% 1 mL (0.04%) | |
| Water 2 mL | Ropivacaine 0.2% 2 mL (0.08%) | |
| Bicarbonate 3 mL | Ropivacaine 0.2% 1 mL (0.04%) | |
| Bicarbonate 2 mL | Ropivacaine 0.2% 2 mL (0.08%) | |
| Normal saline 3 mL | Ropivacaine 1% 1 mL (0.2%) | |
| Normal saline 2 mL | Ropivacaine 1% 2 mL (0.4%) | |
| Water 3 mL | Ropivacaine 1% 1 mL (0.2%) | |
| Water 2 mL | Ropivacaine 1% 2 mL (0.4%) | |
| Bicarbonate 3 mL | Ropivacaine 1% 1 mL (0.2%) | |
| Bicarbonate 2 mL | Ropivacaine 1% 2 mL (0.4%) | |
∗To our knowledge, mepivacaine 1% and bupivacaine 0.25% formulation should be available on the market, although we were unable to obtain them. Therefore, stock solutions of mepivacaine 1% and bupivacaine 0.25% were prepared from mepivacaine hydrochloride 2% W/V [Mepicain 2% (Monico SPA)] and bupivacaine hydrochloride: 5 mg/mL (0.5% W/V) [Marcaina 5 mg/mL (Astra Zeneca)], respectively, by diluting 1 : 1 the commercially available solutions with the relevant vehicles.