Assessing cause and effect can often be challenging in a medical malpractice case. However, when the suspected cause involves a medication, the analysis is typically straightforward. The pharmacology expert will initially assess the medication itself to determine if the pharmacologic profile of the medication is consistent with the presentation of the patient.

Oftentimes, however, there may be multiple causes for the same presentation. A classic example is where a COPD or asthma patient experiences acute respiratory distress while on a medication that is known to compromise the respiratory system. The classic example is with CNS depressants such as benzodiazepines or opioids. These medications are known to cause respiratory depression. So the goal is to determine if the medication is more likely than not to have caused the respiratory distress.

Here, we can easily confirm that with the suspected medication, the pharmacologic profile is in fact consistent with the presentation that we see with the patient and therefore, can be a cause of the respiratory distress. However, to determine if the respiratory distress is secondary to the medication, we may need to also assess the pharmacokinetic profile of the medication.

We can first compare the duration of the symptoms with the duration of action for the medication. We would also compare the time of the known peak effects of the medication to the time period when the patient experiences the most severe symptoms. The pharmacology expert then uses the principles of pharmacokinetic modeling to match the profile of the medication with the symptoms of the patient. Causation is typically confirmed if the symptoms can be superimposed on the PK model.

Further confirmation can be obtained, if the medication is withdrawn and the symptoms subside or abate.