This type of tolerance is most evident with oral ingestion, because other routes of drug administration bypass first-pass metabolism. Enzyme induction is partly responsible for the phenomenon of tolerance, in which repeated use of a drug leads to a reduction of the drugs effect. However, it is only one of several mechanisms leading to tolerance. Behavioral tolerance
Behavioral tolerance occurs with the use of certain psychoactive drugs, where tolerance to a behavioral effect of a drug, such as increased motor activity by methamphetamine, occurs with repeated use. It may occur through drug-independent learning or as a form of pharmacodynamic tolerance in the brain; the former mechanism of behavioral tolerance occurs when one learns how to actively overcome drug-induced impairment through practice. Behavioral tolerance is often context-dependent, meaning tolerance depends on the environment in which the drug is administered, and not on the drug itself. Behavioral sensitization describes the opposite phenomenon. See also


== References ==
With respect to compromised host defenses, patients with severe acute or chronic liver disease are often deficient in complement and may also have malfunctioning of the neutrophilic and reticuloendothelial systems.As for the significance of ascitic fluid proteins, it was demonstrated that cirrhotic patients with ascitic protein concentrations below 1 g/dL were 10 times more likely to develop SBP than individuals with higher concentrations. It is thought that the antibacterial, or opsonic, activity of ascitic fluid is closely correlated with the protein concentration. Additional studies have confirmed the validity of the ascitic fluid protein concentration as the best predictor of the first episode of SBP.In nephrotic syndrome, SBP can frequently affect children but only very rarely can it affect adults. Diagnosis
Infection of the peritoneum causes an inflammatory reaction with a subsequent increase in the number of neutrophils in the fluid. Diagnosis is made by paracentesis (needle aspiration of the ascitic fluid); SBP is diagnosed if the fluid contains neutrophils at greater than 250 cells per mm3 (equals a cell count of 250 x106/L) fluid in the absence of another reason for this (such as inflammation of one of the internal organs or a perforation).The fluid is also cultured to identify bacteria. If the sample is sent in a plain sterile container, 40% of samples will identify an organism, while if the sample is sent in a bottle with culture medium, the sensitivity increases to 72–90%. Prevention
All people with cirrhosis might benefit from antibiotics (oral fluoroquinolone norfloxacin) if:

Ascitic fluid protein <1.0 g/dL.