塩酸プリロカインの局所麻酔効力の増強因子に関する薬理学的研究  [in Japanese] Pharmacological Study on Increase Factor of Local Anesthetic Effects in Prilocaine Hydrochloride.  [in Japanese]

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Abstract

局所麻酔薬の化学的性状により, 効力は大きく変化する。局所麻酔薬の浸透圧とpHをともに検討した報告例はない。そこで, 麻酔効力の増強と局所刺激性の減少を目的として, 塩酸プリロカインの浸透圧とpHの変化による影響を検討した。すなわち, モルモット歯肉および坐骨神経に対する塩酸プリロカインの麻酔効力, NaHCO3の添加の影響, およびブタ角膜に対する局所刺激性を検討し, 次の結果を得た。1. 308mOSMは高低張浸透圧よりも, より強い局所麻酔効力を発現した。2. 308 mOSMの塩酸プリロカインの効力では, pH7.4の深度はpH5.0の約1.6倍, 持続時間は約1.7倍を示した。3. 用時調整ではなく, 塩酸プリロカインをあらかじめNaHCO<SUB>3</SUB>でpH7.0と7.4に調整した場合, NaHCO3の添加の有無による効力の有意差はなかった。4. 歯肉と坐骨神経に対する麻酔効力はほぼ同傾向を示した。5. ブタ角膜に対する塩酸プリロカインの刺激性はpHの増加に伴い減少し, さらに濃度依存性を示した。

Local anesthetic potency is markedly modified by the chemical properties of the local anesthetic solution. However, there are no experimental reports distinguishing among local anesthetic solutions of varying osmotic pressures and pH values. Therefore, in this study, in order to increase local anesthetic potency and reduce the local irritation of prilocaine-HCl, we investigated the effects of varying the pH and osmotic pressure of this solution in: (1) the infiltration potency in guinea-pig gingiva, and (2) the inhibition effects of prilocaine-HCl on tibialis contraction induced by electrical stimulation of the sciatic nerve.<BR>An osmotic pressure of 308 mOSM was optimal for maintaining a higher local anesthetic potency, compared with pressures of 280 mOSM and 380 mOSM. At pH 7.4, the depth of anesthesia was increased approximately 1.6 times, and the duration of anesthesia by 1.7 times, compared with at pH 5.0.<BR>When the effect of sodium bicarbonate was tested in infiltration anesthesia in guinea-pig gingiva at pH 7.0 and 7.4, no significant difference was found between the solutions to which sodium bicarbonate was added and those without it. Overall, there were significant differences when the solutions of pH 5.0 and 7.4 were compared with the control solution of pH 6.6, when inhibition effects on sciatic-nerve stimulation were tested. The same tendencies were also observed for the infiltration anesthesia of prilocaine-HCl. The irritation of this anesthetic on porcine cornea was marked at a low pH and decreased with increasing pH.<BR>These results suggest that prilocaine-HCl has a maximum potency and minimum irritation at pH 7.4 and 308 mOSM. Moreover, the addition of sodium bicarbonate is not essential for enhancing the potency of prilocaine-HCl.

Journal

  • Japanese Journal of Oral Biology

    Japanese Journal of Oral Biology 43(2), 119-132, 2001

    Japanese Association for Oral Biology

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