501 6.7 recorded in this study does not mean that the drug found was necessarily a causative factor of death. For example, some fatal overdose cases were the result of drug combinations. In some overdose cases several drugs had been taken, therapeutically or otherwise, but only one in sufficient quantity to be called an overdose. In still other overdose cases, an additional drug such as lidocaine might have been administered in attempts to revive the victim or to counteract the effects of the drug taken in overdose. It should also be noted that some of the drugs detected and indicated in table 2 may be metabolities of other drugs taken before death.
Similar considerations apply in drug related cases of death.
An example is the case of a victim who was taking amitriptyline for depression, codeine for a cough, alcohol with dinner, and then took an overdose of methaqualone when committing suicide. Even though methaqualone was the drug that caused death, the presence of codeine, morphine, amitriptyline, nortriptyline and ethanol were recorded in table 2. In drug-related cases of death, the frequency of the occurrence of barbiturates decreased, while ethanol, codeine and phencyclidine increased. A comparison of the data in the two cases showed that most drugs were more commonly found in overdose cases than in drug-related cases of death. In contrast, ethanol and phencyclidine were found much more frequently in drug-related cases than in overdose cases of death.