Pepsin and Reflux Laboratory

Dr. Johnston's research laboratory aims to develop new treatments for reflux, which specifically target pepsin.
To contact Dr. Johnson, please email
Learn More about Dr. Johnston
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Research Microscope Lab

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Current and Future Translational Research: Oral Formulation

Human Subject Research

Human Subject Research

This research investigates the effects of oral Fosamprenavir for treatment of LPR in Humans.

  • Efficiency of Fosamprenavir Conversion by Established Human Laryngeal Epithelial Cell Cultures, in the Presence of Saliva and Sera, Measured by High-Performance Liquid Chromatography
  • Proof of Concept, to Assess the Efficacy of Oral Fosamprenavir for Treatment of Laryngopharyngeal Reflux
    Estimated Start Winter 2023
In Vitro Research

In Vitro Research

This research focuses on how amprenavir protects against Pepsin Mediated Laryngeal E-cadherin Cleavage and Matrix Metalloprotease Induction in vitro.

  • Topical Alginate Protection against Pepsin-Mediated Esophageal Damage: E-Cadherin Proteolysis and Matrix Metalloproteinase Induction.
  • The Protease Inhibitor Amprenavir Protects against Pepsin-Induced Esophageal Epithelial Barrier Disruption and Cancer-Associated Changes.

In Vivo Research

In Vivo Research

This research explores the toxicology and outcomes relating to Fosamprenavir for treatment of LPR in animal models.
  • Oral and Inhaled Fosamprenavir Reverses Pepsin-Induced Damage in a Laryngopharyngeal Reflux Mouse Model

Current and Future Translational Research: Inhaled Formulation

Human Subject Research

Human Subject Research

Phase I, Randomized, Placebo Controlled, Dose Escalating Clinical Trial to Assess the Safety and Tolerability of Fosamprenavir via Dry Powder Inhaler in Healthy Volunteers
Estimated Start Spring 2024

In Vivo

In Vivo

This research explores the toxicology and outcomes relating to Fosamprenavir for treatment of LPR in animal models.

  • Toxicology of Inhaled Fosamprenavir as a Dry Powder for Laryngopharyngeal Reflux: Toxicology and Fluid Dynamics Modeling
  • Toxicity of inhaled Fosamprenavir, a dose finding animal model
    o Currently working with KreaMedica, Quebec Canada, on this study
In Vitro

In Vitro

This research investigates the ideal particle size and deposition rate of Fosamprenavir particles for inhalation targeting the larynx via Dry Powder Inhaler

  • Computational Fluid Dynamic analysis of Inhaled Fosamprenavir

Research Timeline for Oral Suspension for LPR, Oral Suspension for GERD and Dry Powder Inhaler for LPR

Fosamprenavir Research | Pepsin and Reflux Lab

European Union of Phonetricians Congress Presentation 2023

Taiwan Voice Society Annual Meeting in conjunction with International Voice Symposium of TCVGH September 2022

Learn more about Dr. Johnston and her team's research accomplishments. 

Grants Awards and Funding

Active Grants:

Title: Inhaled Fosamprenavir for the Treatment of Laryngopharyngeal Reflux (LPR)
Source: Falk Medical Trust Transformational Award
Category: Investigator Initiated Study
Dates: 11/30/2022 - 11/30/2023

Title: Investigation into the mechanisms by which topical alginates preserve esophageal epithelial barrier function during pepsin-acid insult.
Source: Reckitt Benckiser Health Limited
Category: Investigator Initiated Translational Research Grant
Dates: 01/01/23 – 12/31/23

Title: Preparation for clinical trial of fosamprenavir
Source: N-Zyme Biomedical Inc.
Category: Industry Sponsored Grant
Dates: 01/01/2023 – 31/12/2023

Research Interests
  • Extraesophageal reflux
  • Use of pepsin as a marker for extraesophageal reflux
  • Uptake of pepsin by laryngeal epithelial cells & its role in reflux - attributed laryngeal injury & disease
  • Isolate and identification of the receptor with which pepsin interacts on laryngeal epithelial cells
  • New therapeutics for reflux (pepsin inhibitors/receptor antagonists)
  • Role of reflux, specifically pepsin, in laryngopharyngeal cancers
  • Role of pepsin in Barrett’s esophagus and esophageal adenocarcinoma
Society Memberships
  • American Association for Cancer Research
  • Society for Bimolecular Sciences
  • Association for Research in Otolaryngology
  • American Broncho-Esophagological Association
  • Medical College of Wisconsin Cancer Center
  • Clinical and Translational Science Institute of Southeast Wisconsin
  • OESO-Stanford SEMPIRE Multidisciplinary Platform of Esophagology Pilot Center

Current Laboratory and Study Team Members


Nikki Johnston, PhD

Professor, Otolaryngology & Communication Sciences and Microbiology & Immunology


Jonathan Bock, MD



Joel H. Blumin, MD

Chief, Professor


Mark Allen Vukovich, MSN, APNP

Nurse Practitioner


Tina Samuels, MS

Program Manager, Airway, Digestive, & Voice Research


Ally Lesnick

Research Coordinator


Simon Blaine-Sauer

Medical Student


Pelin Ergun, PhD

Postdoctoral Fellow

Recent Publications