Drug Interactions Between Chemotherapy and Antiretrovirals: Making a Difference Behind the Scenes

This account was written by an anonymous HOPA member. If you are interested in submitting your own story about patient care, please respond to the Patient Stories survey created by HOPA’s 2018–2019 Patient Outreach Committee and available at https://www.surveymonkey.com/r/HOPAps. The goal of the survey is to highlight the wonderful work done by oncology pharmacists on a daily basis.

A few years ago, when I was a new clinician practicing on the inpatient lymphoma service at a large academic medical center, a question that I didn’t have an answer for was posed to me: How should one deal with drug interactions between antiretroviral (ARV) agents used to treat HIV/AIDS and the chemotherapeutic agents needed to treat lymphoma?

The result of this question—and a proposal by two physician colleagues—was a collaborative program that lasted for 2 years and helped change the way we triaged patients who had concomitant diagnoses of HIV and lymphoma. The initial proposal was simple: develop a systematic approach to treating these patients.

At the time, very few studies or guidance was available on exactly what to do in these situations. With the limited information available, we drew up a chart of known interactions and how each could be managed. For the most part, the interactions involved either a potential increase in the concentration of the chemotherapeutic agent or an additive effect of QTc prolongation with the use of prophylactic medications or anti-emetics. At the start of the pilot project, our primary focus was the possible increase in the concentration of chemotherapeutic medications and the risk of increased side effects.

Because most of the chemotherapy was administered with curative intent, we decided that if a feasible alternative for an ARV regimen was available when a patient required interacting chemotherapy, then the ARV agent would be changed. If an alternative ARV regimen was not available, the chemotherapy would proceed, but additional monitoring would be implemented. If neither of these options was feasible, then a dose reduction of chemotherapy would be considered as a last resort.

Pharmacists and nurses in the chemotherapy infusion center were educated and provided a list of interactions. The observation of an interaction triggered a call to the clinical pharmacist on the inpatient service (me) so that I could review the interaction and discuss options with the attending physician of record.

For all new patients with concomitant diagnoses of HIV and lymphoma, a consultation with the infectious disease/HIV attending physician collaborating on the project was automatically triggered, as was a thorough review of medications by the clinical pharmacist. A checklist—which included appropriate screening laboratory tests as well as targeted drug interactions to watch for—was also implemented for both consultations.

Over the course of the following 18 months, about a third of the patients screened had changes made to the ARV agents they were receiving, and others underwent additional monitoring for possible side effects. No chemotherapy dose reductions were needed. None of the patients experienced adverse effects that would be considered additive toxicity from the combination of chemotherapy agents and ARV agents.

Reflecting as a clinician on the interventions is interesting. I can share no heartwarming stories of patients coming back to hug us, thank us for changing their ARV medications, or congratulate us on following more closely their HIV-related labs and possible side effects. In fact, most patients probably didn’t give much thought to the changes after they got used to the new ARV medication regimen. What matters is that those small changes possibly prevented adverse events and made the patients’ already difficult journey through cancer treatment a little easier.

Although I subsequently left that position and moved to another state, the program evolved and continued in some form after my departure. The biggest lessons learned were the importance of collaborating with physician colleagues and making an interdisciplinary effort to combat drug interactions. Simple changes, we learned, can make a big impact. The program itself was not complicated and did not require any additional financial resources—only the time and energy of those involved. The possible prevention of side effects—as well as the close follow-up of all patients involved—was well worth the additional effort.