Some adrenergic drugs have been used as vasoconstrictors in local anesthetics for prolongation of acting duration and minimization of side effects. But, the exact role of vasoconstrictors on the clearance of local anesthetics in oral mucosa was
not
investgated. This experiment was carried out to clarify the influences of some adrenergic drugs on the clearance of lidocaine in oral mucosa.
Sprague-Dawley rats were devided into control(no vasoconstrictor) group, epinephrine(1:100,00)-contained group, norepinephrine(1:30,000)-contained group and phenylephrine(1:2,500)-contained group. In urethane(1. 2g/kg) anesthetized rats, 300ul of
2%
lidocaine with or without vasoconstrictor injected in the palatal mucosa. According to time schedule, they were sacrificed by exsanguination immediately, 30 and 60 minutes later after injection, respectively. The palatal mucosa was removed and
homogenized by mechanical force and ultrasonicated in 0.1N HCl(500ul). The samples were centrifuged after akalization. Aliquat of the ksupernatant was injected into HPLC. Also, systemic effects of vasoconstrictors were evaluated with recording
arterial
blood pressures in common carotid artery.
In control animals, lidocatine clearances reached 85.4% and 89.3% at 30 and 60 minutes after injection, respectively. At 30 minutes after injection. Lidocaine clearances of vasoconstrictor contained group were different from control group
significantly(p<0.01). and lidocaine clearance of phenyledphrine contained group appeared higher tha those of the other vasoconstrictor contained groups(p<0.05) But at 60 minutes after injection, only epinephrine contained group had lower
lidocaine
clearance than control group(p<0.01). Intraperitoneal injection of the same dosage of palatal mucosa injecton of these vasoconstrictors did not elicit the change of blood pressure and heart rate.
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