In pharmacology, what does tolerance result in?

Tolerance in pharmacology refers to the phenomenon where a person's response to a drug diminishes with prolonged use, leading to a requirement for higher doses to achieve the same therapeutic effect. When someone develops tolerance, their body becomes accustomed to the drug, leading to adaptations at various levels such as receptor sensitivity, metabolic processes, or cellular response mechanisms. Consequently, to attain the original level of effectiveness, a greater quantity of the drug is necessary. This concept is particularly relevant in the context of pain management, where patients may need increased doses of analgesics over time to maintain the same level of pain relief.

The other options represent different aspects of drug use and pharmacology but do not correspond directly to the concept of tolerance. For instance, while increased risk of addiction relates to the compulsive nature of drug use, it is not a direct result of tolerance itself. Enhanced initial response refers to the immediate effects observed when first using a drug, which contrasts with the diminishing effects seen with tolerance. Lastly, decreased effects of a second drug does not address the primary mechanism or outcomes associated with tolerance to a specific drug.