ABSTRACT
Opioids (morphine, pethidine) are well absorbed with systemic availability and plasma concentrations which are similar to, or even higher than, that after intramuscular administration63 (Figure 3.10). The reduction in post operative pain is comparable from both routes of administration64. Buccal morphine was reported not to be as effective as intramuscular morphine in relieving preoperative anxiety and wakefulness but this may have been produced by the lower bioavailability of the drug from the buccal dose form used6566. A later study demonstrated that intramuscular administration of morphine produced an 8 fold increase in plasma levels compared to buccal administration. Buprenorphine is available as a sublingual commercial product for the treatment of analgesia.
