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Evaluation of the Drug‑Drug Interaction Between Ramipril and Indapamide in Healthy Volunteers

Registered drugNo placebo

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What is this trial about?

A plain-language summary of the goals, design and what participants do

The study involves healthy volunteers and examines how two medicines that are normally used to treat hypertension interact when taken together. One medicine contains ramipril, which helps relax blood vessels, and the other contains indapamide, which helps the body get rid of excess fluid and also lowers blood pressure.

The purpose of the study is to determine whether taking the two medicines at the same time changes how each one is absorbed and processed in the body. Participants will receive a single dose of each medicine alone and then a single dose of both medicines together, with the order chosen at random, while fasting. Blood samples will be collected to assess the pharmacokinetic and bioavailability characteristics of the drugs, and any side effects will be recorded.

The study will evaluate the safety and tolerability of the medicines when used together and will involve only a short period of observation after the single dose administration.

The research process

The trial runs in 7 steps – from screening to follow-up. Each step says what happens and what the team monitors.

Step 1
Enrollment and randomization
After you agree to join the study, study staff will confirm that you meet the health requirements and will assign you to a specific order in which the medicines will be taken.
The order is decided randomly, so you may receive the ramipril tablet first, the indapamide tablet first, or the combination first, according to the study design.
Step 2
First dosing visit
You will arrive at the clinic after an overnight fast, meaning you have not eaten for at least eight hours.
Under the supervision of study staff, you will swallow a single ramipril 10 mg tablet (brand name tritace 10) or a single indapamide 1.5 mg prolonged‑release tablet (brand name tertensif sr), depending on the random order assigned to you.
The tablet is taken by mouth (oral) and is not broken or chewed.
After taking the tablet you will continue to fast for several more hours while the study staff monitor you.
Step 3
Washout period
After the first visit you will wait for a washout period, during which you do not take the study medicines. the length of this period will be explained by the study staff.
Step 4
Second dosing visit
You will return to the clinic after another overnight fast.
This time you will take the other single tablet that you did not receive at the first visit: either the ramipril 10 mg tablet or the indapamide 1.5 mg prolonged‑release tablet.
The tablet is taken whole, by mouth, and you will remain fasting for several hours while observations are made.
Step 5
Second washout period
You will again observe a washout period before the final dosing day, as instructed by the study staff.
Step 6
Co‑administration visit
You will come to the clinic after an overnight fast for the final visit.
You will take both tablets together: one ramipril 10 mg tablet and one indapamide 1.5 mg prolonged‑release tablet.
Both tablets are swallowed whole with water, and you will stay fasting for the required observation time.
Step 7
Study completion
After the final observation period, the study is considered complete for you.
No further study medication will be taken.

Who can join the trial?

14 criteria

Healthy men or women who are between 18 and 60 years old at the time of screening.
Women who can become pregnant must use reliable birth‑control methods or remain sexually abstinent as follows:
- Abstinence for the whole study and up to 2 months after the final visit, if this matches their usual lifestyle.
- If using a non‑hormonal intrauterine device (IUD), it must have been in place for at least 4 weeks before the first dose and continue through the study, plus a barrier method (like a condom) must also be used.
- If using hormonal IUDs or hormonal birth‑control that stops ovulation (pills, patches, rings, injections, implants), it must have been taken without major changes for at least 3 months before the first dose and continue through the study.
- Women who cannot become pregnant must be either:
  - Surgically sterile (e.g., had a hysterectomy, removal of both ovaries, or tubal ligation) confirmed by medical records, or
  - Postmenopausal (no menstrual periods for at least 12 months) with blood tests showing FSH levels ≥ 16.7 IU/L and estradiol ≤ 0.15 nmol/L, indicating menopause.
  - A body‑mass index (BMI) between 18.5 and 30.0 kg/m², measured at screening. (BMI is a calculation using height and weight to assess body size.)
  - Must be a non‑smoker or have stopped smoking at least 3 months before the first dose.
  - Must be of Caucasian race.
  - Willing and able to follow all study procedures, follow the study rules, and provide written informed consent.
  - Medical history that does not show any important health problems at screening.
  - Physical examination that shows no important health issues at screening.
  - A heart test called an ECG (electrocardiogram) that shows no significant abnormalities at screening.
  - All laboratory test results (blood, urine, etc.) must be within normal limits or judged by the doctor as not clinically important.

Who cannot join the trial?

22 criteria

Allergy to ramipril, any other ACE inhibitor (a type of blood‑pressure medicine), indapamide, other sulfonamide drugs (a class of antibiotics), or any inactive ingredients in the study drugs.
Body temperature taken from the ear that is not between 35.9 °C and 37.5 °C during the screening visit.
Having orthostatic hypotension (a drop in blood pressure when standing up) now or in the past.
Having a serious mental illness or being unable to work with the study staff.
Abuse of drugs, alcohol (more than 40 g of pure alcohol per day for men or 20 g for women), solvents, caffeine, or smoking.
Regular use of any medication other than birth‑control pills or hormone‑replacement therapy that has not stayed at the same dose for at least three months before the first dose of the study drug. Vitamins and food supplements might be allowed at the investigator’s discretion.
Use of medicines that can damage major organs (called organ‑toxic drugs) within the past three months.
Taking multiple doses of drugs that change how the liver processes medicines (hepatic metabolism) within the past 30 days.
Any prescription medicine taken systemically (affecting the whole body) within the past 28 days, except birth‑control pills or hormone‑replacement therapy.
Any over‑the‑counter medicine, herbal product, or vaccination taken within the past 14 days.
Donating 500 mL (about a pint) or more of blood in the last 90 days, donating more than 150 mL in the last 30 days, or giving plasma or platelets in the last 14 days.
Having rare inherited conditions that affect sugar digestion, such as galactose intolerance, total lactase deficiency, or glucose‑galactose malabsorption.
Having taken part in another study that used an experimental medical device within the past 60 days.
Having taken another experimental drug in a clinical trial within the past 60 days.
Any other reason the study doctor thinks makes participation unsafe or unsuitable.
A history of serious illness that could change how the study drugs are absorbed, spread, broken down, or removed by the body, including major surgery (except simple surgeries like appendix removal or gallbladder removal).
Any past or current illness that makes taking ramipril or indapamide unsafe, such as swelling under the skin (angioedema), very low blood pressure, unstable blood‑pressure states, severe narrowing of the kidney arteries, kidney failure, severe liver disease (including hepatic encephalopathy), or low potassium levels (hypokalemia).
Veins that are not suitable for repeated blood draws.
A significant illness that occurred within four weeks before the first dose of the study drug.
Positive test results for hepatitis B surface antigen (HBsAg), hepatitis C virus (HCV), or HIV, unless the person has been vaccinated for hepatitis or had a past infection that is now resolved.
Being pregnant or breastfeeding.
Blood pressure while sitting after a five‑minute rest that is not between 115‑140 mmHg (systolic) and 70‑90 mmHg (diastolic), or a heart rate that is not between 50‑100 beats per minute at screening.

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Investigated drugs

Indapamide
is a medication that helps lower blood pressure by causing the kidneys to remove extra water and salt from the body. In this study, it is taken as a prolonged‑release tablet, and the researchers are looking at how the drug behaves when it is taken by itself and when it is taken together with another blood‑pressure medicine.
Ramipril
is an ACE‑inhibitor that lowers blood pressure and can protect the heart and kidneys. In the trial it is given as a regular tablet, and the study examines how the drug is absorbed and processed in the body when taken alone and when combined with indapamide.

What is already known about the treatment

Indapamide
Indapamide is taken by mouth as a prolonged‑release tablet that is swallowed whole. It is an approved, widely used medicine that has been studied for many years. It is mainly used to lower high blood pressure and to help reduce fluid buildup in heart failure. It works by helping the kidneys remove extra salt and water, which lowers fluid in the blood vessels and eases the heart’s workload; it belongs to the class of thiazide‑like diuretics.
Ramipril
Ramipril is taken by mouth as a regular tablet that is swallowed with water. It is an established prescription drug that has been on the market for decades and is well documented in medical literature. It is mainly used to treat high blood pressure, to improve outcomes after a heart attack, and to help manage heart failure. It works by blocking an enzyme that forms a substance which tightens blood vessels, allowing the vessels to stay relaxed and the blood pressure to drop; it is classified as an ACE inhibitor, a type of antihypertensive medicine.