Clinical Study to Investigate the Urinary Excretion of N-nitrosodimethylamine (NDMA) After Ranitidine Administration

The U.S. Food and Drug Administration (FDA) has learned that some ranitidine medicines, including some products commonly known as the brand-name drug Zantac, contain a nitrosamine impurity called N-nitrosodimethylamine (NDMA) at low levels. NDMA is classified as a probable human carcinogen (a substance that could cause cancer) based on results from laboratory tests. NDMA is a known environmental contaminant and found in water and foods, including meats, dairy products, and vegetables.

The FDA has been investigating NDMA and other nitrosamine impurities in blood pressure and heart failure medicines called Angiotensin II Receptor Blockers (ARBs) since 2018. In the case of ARBs, the FDA has recommended numerous recalls as it discovered unacceptable levels of nitrosamines.

FDA has found levels of NDMA in ranitidine active pharmaceutical ingredient and finished drugs that are similar to the levels you would expect to be exposed to if you ate common foods like grilled or smoked meats. FDA has requested removal of all ranitidine products from the market because some ranitidine products have NDMA levels above the acceptable limits (96 nanograms per day or 0.32 parts per million for 300 mg per day of ranitidine) and that levels of NDMA in ranitidine may increase to unacceptable levels over time. However, FDA has not withdrawn approvals of ranitidine new drug applications and abbreviated new drug applications and if a company can show, through scientific data, that their ranitidine product is stable and the NDMA levels do not increase over time to unsafe levels, FDA may consider allowing that ranitidine product back on the U.S. market. The ranitidine that will be used in this study has been tested twice (months apart) and shown to have stable NDMA levels well below the acceptable daily limit. Of note, the risk of NDMA with ranitidine is only relevant with prolonged chronic administration as at the acceptable limit, there is approximately a 1 in 100,000 chance of cancer after 70 years of exposure to that level.

FDA has also conducted tests that simulate the potential formation of NDMA from ranitidine after it has been exposed to acid in the stomach with a normal diet. Results of these tests indicate that NDMA is not formed in typical stomach conditions. Similarly, if ranitidine is exposed to a simulated small intestinal fluid, NDMA is not formed. Other in vitro experiments suggest a combination of nitrites, such as found in processed meats, and an acidic environment potentiate formation of NDMA. For that reason, prior to requesting removal of ranitidine products from the market, the FDA had advised consumers who wished to continue taking these medications to consider limiting consumption of nitrite-containing foods.

Separately, a previous study in 10 healthy volunteers showed that single dose administration of ranitidine 150 mg was associated with ~400-fold increase in urinary NDMA excreted over 24 h. This level of increase is substantially greater than would be expected from laboratory testing. Further evaluation is necessary to determine if and how much NDMA is produced from ranitidine in the human body and whether nitrite-containing foods may potentiate formation of NDMA in vivo.

Ranitidine

Ranitidine is an over-the-counter (OTC) and prescription drug. Ranitidine is an histamine-2 (H2) blocker, which decreases the amount of acid secreted by the stomach. Over-the-counter ranitidine is approved to prevent and relieve heartburn associated with acid ingestion and sour stomach and the approved dosage regiment is up to 150 mg twice a day. Prescription ranitidine is approved for multiple indications, including treatment and prevention of ulcers of the stomach and intestines and treatment of gastroesophageal reflux disease and the approved dosage regimen is up to 150 mg twice a day or 300 mg once a day.

Study Primary Objective

1. To evaluate 24-hour urinary excretion of NDMA after oral administration of ranitidine compared to placebo

Study Exploratory Objectives

1. To evaluate plasma ranitidine, NDMA, and dimethylamine (DMA) after oral administration of ranitidine compared to placebo
2. To evaluate urinary excretion amounts over 24-hours of ranitidine and DMA after oral administration of ranitidine compared to placebo
3. To evaluate 24-hour urinary excretion and plasma concentration of NDMA and DMA with administration of high nitrite/NDMA meals compared to low nitrite/NDMA meals

Study Design

This is a randomized, placebo-controlled, single-dose, 4-period crossover study with 18 healthy subjects. Subjects check-in on Day -2 and receive the following 4 treatments starting on Day 1, with one washout day between treatment days. The treatments consist of oral administration of either a single dose of ranitidine (300 mg) or placebo administered at time 0 hr. All subjects will be provided low nitrite/NDMA meals for the first two periods of the study and high nitrite/NDMA meals for the last two periods of the study. This ordering of meals will allow purchasing a single lot of perishable items for different meals and to simplify meal preparation and serving at the study site. The four treatments are:

1. Ranitidine + low nitrite/NDMA meal;
2. Placebo + low nitrite/NDMA meal;
3. Ranitidine + high nitrite/NDMA meal;
4. Placebo + high nitrite/NDMA meal.

Subjects will report to the study site for screening from Days -28 to -3 and then will return to the site on Day -2 for baseline assessments. Subjects will receive three standardized meals and an evening snack per day starting on Day -1. Subjects will be served meals from a pre-specified menu for check-in and for all washout and treatment days. Subjects will be instructed to finish all their meals within 25 minutes with no leftovers. Subjects will only consume foods served to them at planned meal and snack times.

Two different full day menus of low nitrite/NDMA and high nitrite/NDMA meals have been developed. Additional details regarding the meals will be specified in the Meal Preparation Plan. Meals will be identical for treatments A and B (low nitrite/NDMA meal) of the study and a separate set of identical low nitrite/NDMA meals will be served on the washout days prior to treatment. Likewise, meals will be identical for treatments C and D (high nitrite/NDMA meal) and a separate set of identical high nitrite/NDMA meals will be served on the washout days prior to treatment. The last meal on Day -1, Day 2, Day 4, and Day 6 should be administered at approximately 18:00 to permit at least 12-hour fasting prior to dosing. Outside of meal times, subjects will be provided with distilled water to drink throughout the study.

On study treatment days, the first meal will be provided at the time of dosing. Subjects will be instructed to swallow the medication with approximately 250 mL of room temperature distilled water and begin eating one minute after dosing. Subjects are required to eat each meal in its entirety during the study. If the meal is not finished, the reason should be recorded, along with what was not eaten, and a picture of the remaining food should be taken.

Prior to and following study drug or placebo administration on Day 1, subjects will undergo assessments as described in the Schedule of Events. There will be one day of washout between periods. Participants will be confined in the study clinic from Day -2 until the morning of Day 8.

During the screening visit, the inclusion and exclusion criteria will be reviewed to ensure the subject is eligible for the study. Subjects will be shown the low and high nitrite/NDMA menus and informed that each meal in the menu must be finished in its entirety. The subject must agree to consume all planned meals in order to be eligible to participate. The informed consent form will be reviewed with the subject by a member of the study team and the subject will be encouraged to ask questions to ensure he or she has a good understanding of the study. If the subject is eligible and agrees to participate, the subject will be asked to sign the informed consent form before any study specific procedure is performed, including randomization. Results of all screening tests will be evaluated by the study clinician/investigator against the inclusion/exclusion criteria to confirm subject eligibility. For subjects that are eligible, a molecular diagnostic test for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) will be performed just before or at check-in.

During the study, urine and blood samples for pharmacokinetic assessments will occur before or after drug or placebo administration at the following timepoints:

• Urine samples will be collected using separate collection containers over 24 h. Collection times will occur at 0 (pre-dose), 3, 6, 9, 12, 15, and 24 h. Subjects will be instructed to void their bladder at each collection time and total weight of the sample will be recorded. If a subject must void their bladder at an unscheduled time, the unscheduled voids will be collected, and total weight of the unscheduled voiding will be recorded. The unscheduled voiding sample will be treated, analytically analyzed, and reported as part of scheduled sample collection for determining cumulative amounts of NDMA, ranitidine, and DMA excreted over 24 h.
• Plasma samples will be collected at 0 (pre-dose), 0.5, 1, 1.5, 2, 3, 4, 5, 6, 9, 11, 14, and 24 h post-dose.

Subjects will be discharged from the study after completion of all study procedures. If a subject discontinues from the study prematurely, all procedures scheduled for the end of the study will be performed. Meals (timing and components), activity levels, and general conditions in the study clinic will be standardized to the extent possible on the treatment days.