• Doctor of Pharmacy (University of California San Francisco, 1967)

Courses Taught

  • Pharm 508 (Philosophy of Drug Interactions)

Research Interests

  • Drug Interactions
  • Philosophy of Science (as applied to drug therapy)
  • Philosophy (Friedrich Nietzsche, Michele de Montaigne, Stoicism, Epicureanism, Ernest Becker)


After graduating from UCSF, Dr. Hansten held positions in the Division of Clinical Pharmacology at Stanford University School of Medicine (working on drug interaction research with Professor Stanley N. Cohen) and at Washington State University. He joined UW in 1989. His books on drug interactions have sold over one million copies since 1971 and have been translated into 7 languages. He has lectured widely on drug interactions in North America, and given more than 50 lectures in Europe, Asia, Latin America, and the Middle East. He was a contributing editor to The Medical Letter for many years. He was a founding member of the American College of Clinical Pharmacy, and received teaching awards from students at the University of Washington and Washington State University. He gave the 2007 commencement address at the UCSF School of Pharmacy:

Hansten works in the field of philosophy as well, and has taught philosophy of science at UW and UCSF since 2003. He also has written essays on philosophy and the history of ideas for the Ernest Becker Foundation: and several humanities professors at other universities have assigned his YouTube presentation on Stoic Philosophy to their students:

Webinars and Videos

Tamoxifen Drug Interactions:
Hyponatremia From SSRI/SNRI +Thiazides:
William K. Clifford’s Best Idea:

Selected Recent Publications

Gómez-Lumbreras A, Boyce RD, Villa-Zapata L, Tan M, Hansten PD, Horn J, Malone DC. Drugs that interact with colchicine via inhibition of cyrochrome P450 3A4 and P-glycoprotein: a signal detection analysis using a database of spontaneously reported adverse events (FAERS). Ann Pharmacother. 2023;57:1137-1146.

Hansten PD, Tan MS, Horn JR, Gomez-Lumbreras A, Villa-Zapata L, Boyce RD, Subbian V, Romero A, Gephart S, Malone DC. Colchicine drug interaction errors and misunderstandings: Recommendations for improved evidence-based management. Drug Safety. 2022;46:223-242.

Villa Zapata Boyce RD, Chou E, Hansten PD, Horn JR, Gephart SM, Subbian V, Romero A, Malone DC. QT Prolongation with the use of hydroxychloroquine and concomitant arrhythmogenic medications: A retrospective study using electronic health records data. Drugs Real World Outcomes. 2022;5:1-9.

Villa Zapata L, Carhart BS, Horn JR, Hansten PD, Subbian V, Gephart S, Tan M, Romero A, Malone DC. Serum potassium changes due to concomitant ACEI/ARB and spironolactone therpy: A systemic review and meta-analysis. Am J Health Syst Pharm. 2021;78:2245-2255.

Villa Zapata L, Hansten PD, Panic J, et al. Risk of bleeding with exposure to warfarin and nonsteroidal anti-inflammatory drugs: a systematic review and meta-analysis. Thomb Haemost. 2020: 120:1066-1074.

Villa Zapata L, Hansten PD, Horn JR, et al. Evidence of Clinically Meaningful Drug-Drug Interaction with concomitant use of colchicine and clarithromycin. Drug Safety. 2020:43:661-668.

Hansten PD. The underrated risks of tamoxifen drug interactions. Eur J Drug Metab Pharmacokinet 2018;43:495-508.