Didactic Series HIV Drug-Drug Interactions: OTC and non-prescription medications Kirsten B. Balano, PharmD UCSF School of Pharmacy February 26, 2015 ACCREDITATION STATEMENT: University of California, San Diego School of Medicine is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. The University of California, San Diego School of Medicine designates this educational activity for a maximum of one credit per hour AMA PRA Category 1 Credits. Physicians should only claim credit commensurate with the extent of their participation in the activity. 1
Learning Objectives 1) Counsel patients interested in using herbal supplements with antiretroviral regimens 2) Describe potential interactions between OTC GERD medications and antiretroviral regimens 3) Counsel patients regarding potential harms of recreational drug use and antiretroviral therapy. 2
Strategies to evaluate DDI OBTAIN complete medication history SEARCH for definite vs probable vs theoretical interactions Pharmacokinetic Pharmacodynamic ASSESS clinical significance of interactions MANAGE/MONITOR interaction EDUCATE patient 3
Pharmacodynamic Interactions Antagonism e.g. zidovudine, stavudine (d4t) Additive Toxicities e.g. methadone, citalopram: QT-Prolonging Agents Disease-Drug Interactions Anxiety/Insomnia and Efavirenz 4
Pharmacokinetic Interactions 5
Herbal Supplements Mechanism is primarily based on CYPP450-based interactions Garlic: Decreased saquinavir St. John s Wort: Decreases PI, NNRTI, INSTI (except raltegravir) Ginko Biloba: Case reports decreased efavirenz Grapefruit juice?? 6
Multivitamins Poll Question: What class of drugs have concerns regarding multivitamin drug interactions? NRTI NNRTI PI INSTI Maraviroc All of the above 7
Integrase Inhibitors & divalent cations Integrase inhibitors are subject to complex binding to polyvalent ions. Decreases serum levels of dolutegravir when co-administered with calcium supplements. Pt education: INSTI administered 2 hours before or 6 hours after medicines containing divalent cations. 8
Herbal & Vitamin Interactions References HIV-druginteractions.org Natural Standard (subscription) Pharmacists 9
GERD interactions 10
Antiretrovirals Prefer Acidic ph Atazanavir: including when boosted with ritonavir or cobicistat Rilpivirine Possibly other PI: fosamprenavir, nelfinavir, indinavir, saquinavir, timpranavir 11
Rilpivirine & GERD Management Contraindicated with PPI Limit dosing of H2-blockers to once/day: separate by at least 12 hours 12
Atazanavir & GERD Management Depends upon several HIV/ARV factors: With or without tenofovir Boosted or unboosted Treatment naive or experienced (resistant virus) Depends upon several GERD factors: Dose of PPI Dose of H2-blocker Timing of administration 13
Management Switch Protease Inhibitors Monitor during hospitalizations Counsel about OTC drug use 14
Recreational drug interactions 15
16
17
Learning Objectives 1) Counsel patients interested in using herbal supplements with antiretroviral regimens 2) Describe potential interactions between OTC GERD medications and antiretroviral regimens 3) Counsel patients regarding potential harms of recreational drug use and antiretroviral therapy. 18
Questions 19