Fast-acting Fentanyl has been approved for the treatment of breakthrough pain.This is a pure selective agonist for mu-type morphine receptors.Because it is lipophilic, it can be absorbed through the mucosa and is commercially available in oral (sublingual) and nasal (spray) forms.The latter provides very fast analgesic action, in 10 to 30 minutes, which makes it an interesting pharmaceutical product to use.However no studies have shown that it is clinically superior to other fast-acting opioids for the treatment of breakthrough pain.

The use of oral fentanyl as a rescue dose medication in patients being treated with morphine must follow precise titration rules that are fentanyl-specific.As with any titration, the optimal dose cannot be predicted and the lowest available dose must be used first.The optimal dosage for each patient will only be determined after administering increasing doses when breakthrough pain occurs, which is a drawback when trying to quickly relieve acute pain.

Unlike the others, a fentanyl-based rescue dose is not calculated as a function of the 24 hour background opioid treatment dose!