Effect of Licorice and Hydrochlorothiazide on Plasma Potassium

This study has been completed.
Information provided by:
University of Oulu
ClinicalTrials.gov Identifier:
First received: January 17, 2008
Last updated: December 10, 2009
Last verified: December 2009
This clinical trial is designed to study the effect of the combination of licorice and hydrochlorothiazide on plasma potassium levels in volunteers. In one arm, 10 healthy volunteers will be given 32 grams of licorice a day together with a 25 mg dose of daily hydrochlorothiazide for 14 days. This combination is compared with 32 grams of licorice a day for 14 days given in the other arm. The study is a randomized, open-label cross-over trial. There is at least a 3-week wash-out between the arms. The hypothesis is that the combination of licorice and hydrochlorothiazide will cause hypokalemia. The main outcome measure is the change in the plasma level of potassium between the arms.

Condition Intervention Phase
Drug: Hydrochlorothiazide
Dietary Supplement: Licorice
Phase 4

Study Type: Interventional
Study Design: Allocation: Randomized
Endpoint Classification: Safety Study
Intervention Model: Crossover Assignment
Masking: Open Label
Primary Purpose: Treatment
Official Title: Effect of Licorice and Hydrochlorothiazide on Plasma Potassium

Resource links provided by NLM:

Further study details as provided by University of Oulu:

Primary Outcome Measures:
  • Plasma Potassium [ Time Frame: Baseline and 2 weeks ] [ Designated as safety issue: Yes ]

Enrollment: 10
Study Start Date: February 2008
Study Completion Date: January 2009
Primary Completion Date: January 2009 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Active Comparator: Licorice Dietary Supplement: Licorice
Licorice candy 32 grams a day for 14 days.
Other Name: Pepe Original candy
Active Comparator: Licorice and HCTZ Drug: Hydrochlorothiazide
Hydrochlorothiazide 25 mg a day for 14 days.
Other Name: Hydrex semi, ATC C03AA03


Ages Eligible for Study:   18 Years to 40 Years
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • Healthy volunteer
  • Age 18-40 years

Exclusion Criteria:

  • Any continuous medication
  • Any significant disease
  • Hypotension or hypertension
  • Allergy to licorice or hydrochlorothiazide
  • Pregnancy and breast feeding
  • Fear of needles and previous difficult blood samplings
  • Substance abuse
  • Participation in another clinical drug trial within 1 month of enrollment
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT00605202

Oulu University Hospital
Oulu, Finland, 90220
Sponsors and Collaborators
University of Oulu
Principal Investigator: Markku Savolainen, MD Oulu University Hospital
  More Information

Responsible Party: Professor Markku Savolainen, Oulu University Hospital
ClinicalTrials.gov Identifier: NCT00605202     History of Changes
Other Study ID Numbers: Lakritsi ja hypokalemia 
Study First Received: January 17, 2008
Results First Received: August 13, 2009
Last Updated: December 10, 2009
Health Authority: Finland: Finnish Medicines Agency

Additional relevant MeSH terms:
Metabolic Diseases
Water-Electrolyte Imbalance
Antihypertensive Agents
Cardiovascular Agents
Membrane Transport Modulators
Molecular Mechanisms of Pharmacological Action
Natriuretic Agents
Pharmacologic Actions
Physiological Effects of Drugs
Sodium Chloride Symporter Inhibitors
Therapeutic Uses

ClinicalTrials.gov processed this record on April 27, 2016