The Effect of Losartan on Cephalexin

NCT07300670 | Recruiting Phase 1

• 2 other identifiers: T2025/258582025-525059-23-00
• Study Type: interventional
• Target: 12
• Locations: 1 country
• Sites: 1

Brief Summary

The goal of this clinical trial is to investigate the effects of the blood pressure-lowering drug losartan on the blood levels and urinary excretion of the antibiotic cephalexin during simultaneous and staggered ingestion in healthy volunteers. The main questions it aims to answer are:

1. 1.Does losartan affect cephalexin levels and excretion when ingested at the same time?
2. 2.Does a three-hour interval between ingestion of losartan and cephalexin eliminate a possible effect?

Conditions

Possible Interaction Between Losartan and Cephalexin; Healthy

Keywords

losartan; cephalexin; pharmacokinetic interaction; absorption

Outcome Measures

Primary Outcomes (1)

• Plasma concentrations of cephalexin over time, the cumulative urinary excretion of cephalexin, and the pharmacokinetic parameters derived from these measurements following simultaneous or staggered ingestion of losartan

  up to 8 hours after ingestion of cephalexin on three consecutive days separated by at least one-week intervals

Secondary Outcomes (1)

• Plasma concentrations of losartan and losartan carboxylic acid over time, the cumulative urinary excretion of losartan and losartan carboxylic acid, and the pharmacokinetic parameters derived from these measurements

  up to 11 hours after ingestion of losartan or water on three consecutive days separated by at least one-week intervals

Other Outcomes (1)

• Plasma and urinary concentrations of endogenous and diet-derived metabolites, and the effects of genetic variants and other individual factors on the pharmacokinetic parameters of cephalexin and losartan

  up to 11½ hours on three consecutive days separated by at least one-week intervals

Study Arms (6)

Sequence A

OTHER

water at 7.30, cephalexin 500 mg at 10.30; then water at 7.30, losartan 100 mg and cephalexin 500 mg at 10.30; then losartan 100 mg at 7.30, cephalexin 500 mg at 10.30

Drug: losartan; Drug: cephalexin

Sequence B

OTHER

water at 7.30, losartan 100 mg and cephalexin 500 mg at 10.30; then water at 7.30, cephalexin 500 mg at 10.30; then losartan 100 mg at 7.30, cephalexin 500 mg at 10.30

Drug: losartan; Drug: cephalexin

Sequence C

OTHER

losartan 100 mg at 7.30, cephalexin 500 mg at 10.30; then water at 7.30, losartan 100 mg and cephalexin 500 mg at 10.30; then water at 7.30, cephalexin 500 mg at 10.30

Drug: losartan; Drug: cephalexin

Sequence D

OTHER

water at 7.30, cephalexin 500 mg at 10.30; then losartan 100 mg at 7.30, cephalexin 500 mg at 10.30; then water at 7.30, losartan 100 mg and cephalexin 500 mg at 10.30

Drug: losartan; Drug: cephalexin

Sequence E

OTHER

water at 7.30, losartan 100 mg and cephalexin 500 mg at 10.30; then losartan 100 mg at 7.30, cephalexin 500 mg at 10.30; then water at 7.30, cephalexin 500 mg at 10.30

Drug: losartan; Drug: cephalexin

Sequence F

OTHER

losartan 100 mg at 7.30, cephalexin 500 mg at 10.30; then water at 7.30, cephalexin 500 mg at 10.30; then water at 7.30, losartan 100 mg and cephalexin 500 mg at 10.30

Drug: losartan; Drug: cephalexin

Interventions

losartan DRUG

100 mg tablet orally, single dose

Also known as: Cozaar

Sequence A; Sequence B; Sequence C; Sequence D; Sequence E; Sequence F

cephalexin DRUG

500 mg tablet orally, single dose

Also known as: Kefalex, Kefexin

Sequence A; Sequence B; Sequence C; Sequence D; Sequence E; Sequence F

Eligibility Criteria

• Age: 18 Years - 40 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• written informed consent
• years of age
• good health
• systolic blood pressure of at least 115 mmHg
• all screening laboratory results (P-Krea, Pt-GFReEPI, P-Na, P-K, P-ALAT, P-AFOS, P-GT, B-PVK+T) acceptable; minor deviations from reference ranges are acceptable at the discretion of a physician-scientist with the exceptions of Pt-GFReEPI which must be at or above the reference limit and P-K which must be at or below the higher reference limit (Reference limits: Tyks Laboratories, Turku University Hospital)
• regarding female subjects, a negative pregnancy test (S-HCG-O) before the study, and the use of a highly effective contraceptive method (e.g. copper intrauterine device, bilateral tubal occlusion, vasectomised partner, or abstinence from heterosexual intercourse), according to CTFG Recommendations related to contraception and pregnancy testing in clinical trials, are required

You may not qualify if:

• inability to provide written informed consent in Finnish
• remarkable illness
• confirmed or reasonably suspected allergy to cephalexin, amoxicillin, benzylpenicillin, phenoxymethylpenicillin, piperacillin, cefaclor, or cefamandole
• confirmed or reasonably suspected severe delayed allergic reaction to any beta-lactam antibiotic
• underweight (BMI less than 18.5 kg/m2)
• obesity (BMI greater than 30 kg/m2)
• smoking
• regular medication, including hormonal contraception in the form of pills, intrauterine device, subdermal implant etc.
• current or planned pregnancy, and breastfeeding
• less than three months elapsed since a prior clinical trial
• less than three months elapsed since donating blood

Sponsors & Collaborators

• Aleksi Tornio: lead
• Turku University Hospital: collaborator
• University of Turku: collaborator
• University of Helsinki: collaborator
• Helsinki University Central Hospital: collaborator

Study Sites (1)

Unit of Clinical Pharmacology, Turku University Hospital

Turku, Southwest Finland, FI-20520, Finland

RECRUITING

MeSH Terms

Interventions

Losartan; Cephalexin

Intervention Hierarchy (Ancestors)

Biphenyl Compounds; Benzene Derivatives; Hydrocarbons, Aromatic; Hydrocarbons, Cyclic; Hydrocarbons; Organic Chemicals; Imidazoles; Azoles; Heterocyclic Compounds, 1-Ring; Heterocyclic Compounds; Tetrazoles; Cephalosporins; beta-Lactams; Lactams; Amides; Thiazines; Sulfur Compounds; Heterocyclic Compounds, 2-Ring; Heterocyclic Compounds, Fused-Ring

Study Officials

• Aleksi Tornio, M.D., Ph.D.

  Unit of Clinical Pharmacology, Turku University Hospital

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Aleksi Tornio, M.D., Ph.D.

CONTACT

+358504765715; aleksi.tornio@utu.fi

Study Design

• Study Type: interventional
• Phase: phase 1
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER GOV
• Responsible Party: SPONSOR INVESTIGATOR
• PI Title: Chief Physician

Study Record Dates

• First Submitted: November 27, 2025
• First Posted: December 24, 2025
• Study Start: March 4, 2026
• Primary Completion (Estimated): May 8, 2026
• Study Completion (Estimated): May 8, 2026
• Last Updated: March 25, 2026

Record last verified: 2026-03

Data Sharing

• IPD Sharing: Will not share

Locations

FI (1)