Cardiac or central nervous system toxicity may result when standard lidocaine doses are administered to patients with circulatory failure. This may be due to the following reason -

Ans. is 'a' i.e., Lidocaine concentration are initially higher in relatively well perfused tissues such as brain and hea o Lidocaine is a rapidly acting drug because of its rapid distributtion to well perfused tissues such as brain and hea.o Circulatory failure is characterized by decreased cardiac output and a consequent decrease in hepatic blood flow.As a result metabolic clearance ofLidocaine in liver is diminshed and its elemination t 1/2 is increased. Consequently Lidocaine concentration is initially increased in these relatively well perfused tissues (brain and hea) even with usual doses and toxicity results.