TM is a 23-year-old male presents to his community pharmacy to pick up Biktarvy for his newly diagnosed HIV-1 infection.  His past medical history includes GERD for which he takes pantoprazole 40 mg by mouth daily.  When asked about over-the-counter medication use, TM reports taking Tums occasionally for breakthrough symptoms.  What is an important point to counsel the patient on at pick up?

A. Biktarvy should be taken 2 hours before or 6 hours after taking Tums when in a fasting state

B. Biktarvy requires acid for optimal absorption so both pantoprazole and Tums should be avoided

C. Biktarvy must be taken 30 minutes prior to a meal with the pantoprazole for optimal absorption and viral suppression

D. Pantoprazole must be discontinued because Biktarvy is contraindicated in patients taking proton pump inhibitors 

Answer with rationale:

Learning antiretroviral therapy (ART) can seem daunting.  A good place to start is learning the different components of the agents and which therapeutic classes those components belong to.  Knowing if you are dealing with an integrase strand inhibitor (INSTI), a protease inhibitor (PI), a non-nucleoside reverse transcriptase inhibitor (NNRTI), a nucleoside reverse transcriptase inhibitor (NRTI), or any combination of those classes is half the work.  For this case, the patient was prescribed Biktarvy which contains bictegravir, tenofovir alafenamide, and emtricitabine (an INSTI and 2 NRTIs).  One concern with ART is virologic failure.  Some of the causes of virologic failure include nonadherence because of adverse drug effects, drug interactions leading suboptimal serum concentrations, taking the medication incorrectly with regards to meals, etc.  These are all things that are important to know and counsel patients on in order to set them up for success.

Answer A is correct.  Biktarvy contains bictegravir which is an INSTI that has a chelation drug interaction with polyvalent cation-containing antacids such as Tums.  This interaction leads to decreased serum concentrations of bictegravir and therefore reduced efficacy.  This can be managed by spacing out the dose of Biktarvy 2 hours before or 6 hours after taking a dose of Tums in patients who are in a fasting state. When eating food with Biktarvy and Tums, the two medications can be taken together. Patients taking aluminum or magnesium antacids or laxatives must take the Biktarvy 2 hours before or 6 hours after these products, regardless of fasting or eating with food. 

Answer B is incorrect.  Biktarvy can be given with acid suppression medications like proton pump inhibitors because acid is not required for absorption. The issue with Tums is the calcium creating a potential chelation drug interaction affecting bioavailability of Biktarvy. 

Answer C is incorrect.  None of the components of Biktarvy have their bioavailability affected by food, so Biktarvy can be taken without regard to meals. Proton pump inhibitors are optimally given 30 minutes prior to a meal to increase the chance of working on as many active proton pumps as possible which eating will stimulate. 

Answer D is incorrect.  None of the components of Biktarvy are contraindicated in patients taking proton pump inhibitors (PPIs).  PPIs are contraindicated in patients taking oral rilpivirine (a non-nucleoside reverse transcriptase inhibitor - NNRTI) or HIV treatment experienced patients taking atazanavir (a protease inhibitor) because PPIs can greatly reduce their absorption. HIV treatment naive patients may take PPIs, but it must be boosted with ritonavir or cobicistat and given 12 hours after the PPI or other acid blockers like vonoprazan. Note than intramuscular rilpivirine would be acceptable with PPI therapy due to the route of administration. 

Brands/generics covered:

Biktarvy (bictegravir-tenofovir alafenamide-emtricitabine), Edurant (rilpivirine), Protonix (pantoprazole), Reyataz (atazanavir), Tums (calcium carbonate)

Naplex content domains covered:

1.A.1

Domain 1 Foundational Knowledge for Pharmacy Practice- A. Pharmaceutical Science Principles and Concepts 1. Pharmacology

2.A.1

Domain 2 Medication Use Process- A. Prescriptions and Medication Order Interpretation 1. Drug Names and Therapeutic Classes

2.A.2

Domain 2 Medication Use Process- A. Prescriptions and Medication Order Interpretation 2. Indications, Usage, and Dosing Regimens

3.C.3

Domain 3 Person-Centered Assessment and Treatment Planning- C. Patient Health Conditions, including special populations and medication-related factors 3. Interactions (eg, drug-drug, drug-condition, drug-food, drug-allergy, drug-laboratory)