Why is the effect of local anaesthesia slow in infected tissues
In case of infection there is acidic pH of tissue, and in that case local anaesthetics are mostly in ionized form. Ionized form of local anaesthetics is the one that binds to sodium channels, but non-ionized form is the one that is important for membrane penetration. That is the reason for delayed onset of local anaesthetics in site of infection.
Less vascularity causing poor diffusion of drug
Rich in enzymes that metabolize the drug
Low extracellular pH that hinders diffusion of drug into cell
Rich in K+ that inhibits binding of the drug to the receptor