ABSTRACT
The stability of amitriptyline, nortriptyline, desipramine and imipramine in formalin-fixed human liver tissue and formalin solutions was investigated. The levels of the tricyclic and its primary demethylated metabolite in the frozen liver were determined and compared with levels obtained in the formalin-fixed liver and formalin solutions in which the liver was stored. It was obvious that some methylation of the secondary amine, nortriptyline, to the corresponding tertiary amine, amitriptyline, and of desipramine to imipramine took place in the formalin environment. Nortriptyline was not detected in most cases, suggesting that it may degrade more rapidly than desipramine. There was no consistent ratio between the concentration of the drug in the frozen liver tissue versus formalin-preserved tissue or versus formalin solution. The methylation rates of the secondary amines could not be quantitated. Storage of the liver tissue in formalin at room temperature resulted in leaching of the drugs into the formalin solution. The drugs tested may be detected for up to 22 months in the formalin-fixed liver and in the formalin medium.