Possible Interaction Between Losartan and CephalexinPhase 1KEFALOSNCT07300670
The Effect of Losartan on Cephalexin
A Phase 1 study testing losartan and cephalexin in people with Possible Interaction Between Losartan and Cephalexin and Healthy, run by Aleksi Tornio at 1 site in Finland.
Trial 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. Read more about this study
- Who is it for?
- Ages 18 to 40 yearsHealthy volunteers can take part
- Conditions the study is for
- Possible Interaction Between Losartan and Cephalexin, Healthy
- What is being tested?
- losartan and cephalexin
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 13 participants
- Where
- 1 siteFinland
- Study dates
- 4 Mar 2026to 8 May 2026
- Phase
- Phase 1
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 40 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- written informed consent
- 18-40 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
Who cannot join
- 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)
Show all 11Show fewer
- 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
Trial locations and contacts
1 site in 1 country.
Finland1 site
Unit of Clinical Pharmacology, Turku University Hospital
Turku, Southwest Finland, FI-20520
About this study
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:
- Does losartan affect cephalexin levels and excretion when ingested at the same time?
- Does a three-hour interval between ingestion of losartan and cephalexin eliminate a possible effect?
Read more
Researchers will compare the effects of losartan ingested at the same time, losartan ingested three hours prior, and no losartan ingested on oral cephalexin in each participant to see whether an interaction exists and could be avoided.
Participants will visit the research laboratory on three days during which they will ingest single doses of losartan at the same time with, three hours prior to, and not at all prior to ingesting single doses of cephalexin.
- Being tested
- losartan, cephalexin
- Keywords
- losartan, cephalexin, pharmacokinetic interaction, absorption
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
losartanDrug
Also called Cozaar
100 mg tablet orally, single dose
cephalexinDrug
Also called Kefalex, Kefexin
500 mg tablet orally, single dose
| Study group | Role | What they receive |
|---|---|---|
| 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 Receives: 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 Receives: 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 Receives: 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 Receives: 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 Receives: 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 Receives: Drug: losartan; Drug: cephalexin |
What is being measured
The primary outcome is the main question the study is designed to answer.
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
Measured: 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
following simultaneous and staggered ingestion of cephalexin
Measured: up to 11 hours after ingestion of losartan or water on three consecutive days separated by at least one-week intervals
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted24 Dec 2025
- Study start4 Mar 2026
- Primary completion8 May 2026
- Study completion8 May 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Possible Interaction Between Losartan and CephalexinStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 1
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- None (open label)
- Enrolment
- 13 participants (actual)
Sponsor and investigators
- Lead sponsor
- Aleksi Tornio
- Sponsor type
- Other government
- Collaborators
- Turku University Hospital, University of Turku, University of Helsinki, Helsinki University Central Hospital
- Responsible party
- Sponsor-investigator, Aleksi Tornio, Turku University Hospital
- Investigators
- Aleksi Tornio, M.D., Ph.D., Principal investigator, Unit of Clinical Pharmacology, Turku University Hospital
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07300670
- Sponsor's protocol ID
- T2025/25858
- Other IDs
- 2025-525059-23-00, 2025
- Acronym
- KEFALOS
- Status last verified
- May 2026
- First submitted
- 27 Nov 2025
- Last updated
- 1 Oct 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: The individual data supporting the findings of this study cannot be made available to other researchers to protect the privacy of the study subjects in accordance with European legislation and ethical requirements.
Study at a glance
From the registry record, last updated by the sponsor on 1 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Effect of Losartan on Cephalexin
- ClinicalTrials.gov ID
- NCT07300670
- Acronym / sponsor ID
- KEFALOS / T2025/25858
- Keywords
- losartan, cephalexin, pharmacokinetic interaction, absorption
- Phase
- Phase 1
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 13 participants (actual)
- Lead sponsor
- Aleksi TornioOther government
- Collaborators
- Turku University Hospital, University of Turku, University of Helsinki, Helsinki University Central Hospital
- Study start
- 4 Mar 2026 (actual)
- Primary completion
- 8 May 2026 (actual)
- Study completion
- 8 May 2026 (actual)
- First posted
- 24 Dec 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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:
- Does losartan affect cephalexin levels and excretion when ingested at the same time?
- Does a three-hour interval between ingestion of losartan and cephalexin eliminate a possible effect?
Researchers will compare the effects of losartan ingested at the same time, losartan ingested three hours prior, and no losartan ingested on oral cephalexin in each participant to see whether an interaction exists and could be avoided.
Participants will visit the research laboratory on three days during which they will ingest single doses of losartan at the same time with, three hours prior to, and not at all prior to ingesting single doses of cephalexin.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- None (open label)
- Number of arms
- 6
| Arm | Type | Receives |
|---|---|---|
| Sequence A | Other | Drug: losartan, Drug: cephalexinwater 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 |
| Sequence B | Other | Drug: losartan, Drug: cephalexinwater 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 |
| Sequence C | Other | Drug: losartan, Drug: cephalexinlosartan 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 |
| Sequence D | Other | Drug: losartan, Drug: cephalexinwater 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 |
| Sequence E | Other | Drug: losartan, Drug: cephalexinwater 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 |
| Sequence F | Other | Drug: losartan, Drug: cephalexinlosartan 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 |
Who may qualify
- Ages
- 18 to 40 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (6 listed)
- written informed consent
- 18-40 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)
Key exclusion criteria (11 listed)
- 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)
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| losartanAlso: Cozaar100 mg tablet orally, single dose | Drug | Sequence A, Sequence B, Sequence C, Sequence D, Sequence E, Sequence F |
| cephalexinAlso: Kefalex, Kefexin500 mg tablet orally, single dose | Drug | Sequence A, Sequence B, Sequence C, Sequence D, Sequence E, Sequence F |
Primary outcome
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
Time frame: up to 8 hours after ingestion of cephalexin on three consecutive days separated by at least one-week intervals
1 secondary outcome
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
Time frame: up to 11 hours after ingestion of losartan or water on three consecutive days separated by at least one-week intervals
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 1 Oct 2026.
- Individual participant dataSharing planned: No. The individual data supporting the findings of this study cannot be made available to other researchers to protect the privacy of the study subjects in accordance with European legislation and ethical requirements.
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Aleksi Tornio, M.D., Ph.D. principal investigator
Unit of Clinical Pharmacology, Turku University Hospital
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 1 study testing losartan and cephalexin in people with Possible Interaction Between Losartan and Cephalexin and Healthy, run by Aleksi Tornio at 1 site in Finland.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 6 inclusion and 11 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 1 Oct 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Finland. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
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 (time frame: up to 8 hours after ingestion of cephalexin on three consecutive days separated by at least one-week intervals). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 1 Oct 2026.