Table 5. Summary of some pharmacological differences between tramadol and tapentadol in dogs and cats [16–18,20,25,26,31,35,93,95,99].
| Tramadol | Tapentadol | |||
|---|---|---|---|---|
| Dogs | Cats | Dogs | Cats | |
| Administration routes | IV, IM, PO, SC | IV, PO | ||
| Absorption | Intestinal | Intestinal | ||
| Oral bioavailability | 60%–83% | 60%–90% | 4.4% | Unknown |
| Plasma concentration (ng/ml) (M1) | 146–449 | 366–850 | 240–3640 | 906–1,406 |
| Metabolism | Hepatic | Hepatic | ||
| Main metabolites | M2 | M1 and M5 | Tapentadol-O-glucoronide | |
| Active metabolite | M1 | Active parent compound | ||
| Terminal half-life (M1) | 1–2 h | 4–6 h | 2–5 h | 1–3 h |
| Excretion | Urine and feces | Urine and feces | ||
| Interactions | Combination with a SSRI can cause serotonin syndrome Naloxone, alpha-2 antagonist, and 5-HT partially blocks |
The antagonist atipamezole, and yohimbine could potentially block the effect of tapentadol | ||
| Differences between species | CYP polymorphism affects its analgesic efficacy in dogs | It does not rely on metabolism to produce its therapeutic effects, reducing the inter-species differences. | ||
SSRI = Selective serotonin reuptake inhibitor.