How and where a medication is distributed throughout the body has implications on its prospect of effectiveness and likeliness of adverse effects or toxicities. A pharmacology expert can evaluate and opine with reasonable pharmaceutical certainty the association between drug exposure and outcome, including the relevance of drug distribution factors to an outcome.
The major considerations of drug distribution that may apply to a medical malpractice, drug toxicity or medication error associated case include:
- Did the medication reach the intended site of action?
- Did the medication distribute to a site that elicited an adverse effect?
- Were the known pharmacologic and/or pharmacokinetic properties of a medication with regard to distribution given appropriate consideration?
Did the medication reach the intended site of action?As previously explained, a variety of factors impact whether a particular medication, dosage form or route of administration is conducive to systemic absorption. In a similar fashion, a number of factors including molecule size, polarity, lipophilicity, transporters and acid-base characteristics influence WHERE a systemically administered drug circulates throughout the body. This is especially relevant in the treatment of infectious diseases with antibiotics. In the treatment of central nervous system (CNS) infections like meningitis, selection and administration of antibiotics that achieve effective concentrations in the brain or CNS fluids is critical to delivering effective treatment; failure to properly select an antibiotic that has such distribution characteristics could have devastating results.
Did the medication distribute to a site that elicited an adverse effect? Generally, both clinical and adverse effects of medications depend on that agent reaching a target site. However, the site of adverse effect may or may not be the same site of clinical effect. For example, a blood pressure medicine that works on the heart or vasculature may also penetrate the CNS and elicit adverse effects in the brain. Amiodarone, a drug used to treat heart arrhythmias, is widely distributed into locations beyond the circulatory compartment, including to lung tissue. Adverse effects including pulmonary fibrosis have been identified in amiodarone treated patients while not seen in other antiarrhythmics with different distribution kinetics.
Were the known pharmacologic and/or pharmacokinetic properties of a medication with regard to distribution given appropriate consideration? In a litigation case involving medications, a pharmacology expert should consider all aspects of a medication, including drug distribution factors. In different circumstances, either fault or defensibility in a med mal case may hinge on the identification, assessment and reasonable attribution of variables connecting drug distribution factors with clinical or adverse outcomes.
For these and other reasons, consider engaging an academically trained Forensic Pharmacy Expert with broad clinical experience on your next medical litigation case.