Which of the following is NOT a property of an ideal local anesthetic?

The ideal local anesthetic is characterized by several key properties that enhance its effectiveness and safety in clinical use. Among these properties, satisfactory duration of action is essential, as it allows the anesthetic effect to last long enough to perform a procedure without requiring frequent reinjection. Low cost is also a desirable attribute, as it makes the anesthetic more accessible to a broader range of patients and healthcare settings. Additionally, the absence of systemic reactions is crucial, as it minimizes the risk of adverse effects on the patient, ensuring a safer anesthetic experience.

Rapid action is certainly an advantage; however, it is important to note that the focus is primarily on achieving adequate pain control while minimizing the risk of complications. The option stating "rapid action at high concentrations" suggests that it is acceptable to use high concentrations, which can increase the risk of systemic toxicity and adverse effects. The ideal local anesthetic should provide effective pain relief with appropriate concentrations, without necessitating high doses that could lead to systemic reactions. Thus, while rapid onset is desirable, the emphasis on high concentrations creates a potential risk, which makes it less aligned with the properties of an ideal local anesthetic.