Acute toxicity (LD50 and CD50) of lidocaine and prilocaine in combination with adrenaline and felypressin.

The toxicity of the combination of vasoconstrictors to local anaesthetic solutions has been debated since its first use in the beginning of this century. A combination of two vasoconstrictors to a local anaesthetic has been proposed by some researchers. In this study they were evaluated the acute toxicity (lethal dose 50%, convulsion dose 50%) and latency times of loss of righting reflex and convulsion as well as the duration of convulsion) of 2% lidocaine or 3% prilocaine, when administered in combination with adrenaline and felypressin at various concentrations. Lethal dose 50% studies showed that for both anaesthetics the solutions with higher concentrations of adrenaline were more toxic. The opposite was observed in the convulsion dose 50% studies. No alterations were observed in the control groups. All lidocaine solutions increased the latency of loss of righting reflex. The latency of convulsion was increased in some groups, but once the convulsion was achieved there was no difference in its duration. There was no statistical difference among prilocaine groups for any of the variables studied. Based on the experimental model studied, it was concluded that there is no advantage in the association of two vasoconstrictors concerning the toxicity of lidocaine and prilocaine solutions.

[Can choice of medications and adjuvants reduce risks of local anesthetic complications?]. / Kann durch die Auswahl von Medikamenten und Adjuvantien das Komplikationsrisiko von Lokalanästhesien gesenkt werden?

Local anesthetic agents in high concentrations may cause local irritation by ischemia especially after the use of adrenaline whereas felypressin has no tissue-irritating properties. Adrenaline but not felypressin increases the intravenous systemic toxicity. Noradrenaline has to be avoided as a vasoconstrictor. An aspiration test before injection will decrease the risk of inadvertent intravenous injection.

Examination of toxicity of diisopropylammonium dichloracetate (DADA), remedies for cardiac diseases, toward isolated rat hepatocytes.

Oxygen uptake (OU) and cell viability (CV) of isolated rat hepatocytes as a part of the indexes of hepatopathy were determined following treatment with DADA, the active principle of pangamic acid. DADA increased OU at high concentrations, but not at low ones. However, CV became higher as the concentration became lower. DADA led to no remarkable toxicity when used alone. When the mixture of DADA and calcium gluconate was tested, DADA showed no palliative action; nor did it when combined with other hepatotoxins such as trapidil, rifampicin, hexobarbital, thiopental sodium, and Citanest-octapressin.