The main purpose of this study is to measure the level of active ingredient of the study medicine (nirmatrelvir) that is secreted in human breast milk when it is given to healthy breastfeeding women. The study medicine consists of two medicines, nirmatrelvir and ritonavir. We are seeking female participants who are: * Actively breast-feeding (lactating) at least 12 weeks postpartum; * Age between 18 to 55 years and not currently pregnant; * Have a Body Mass Index (BMI): 17.5 kg/m2; and a total body weight \>50 kg (110 lb). Participants will take the study medicine by mouth for a total of 3 times over 2 days (2 morning doses and 1 evening dose) at the study clinic. We will periodically collect breast milk from day 2 to 4 to measure the level of nirmatrelvir and ritonavir in it. A safety follow up call will be conducted around 28-35 days from the last dose to monitor any reactions participants may have to the study medicine.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
OTHER
Masking
NONE
Enrollment
8
nirmatrelvir/ritonavir
nirmatrelvir/ritonavir
Pfizer Clinical Research Unit - Brussels
Brussels, Bruxelles-capitale, Région de, Belgium
The Maximum Observed Concentration of Nirmatrelvir in Breast Milk Over the Dosing Interval
The maximum observed concentration and was directly observed from data.
Time frame: At Day -1 (24 Hours Prior to Dosing on Day 1), Pre-dose on Day 1, 0 to 2, 2 to 4, 4 to 8, 8 to 12, 12 to 24, 24 to 32, 32 to 40 and 40 to 48 Hours Post-dose on Day 2
Time to Reach Cmax of Nirmatrelvir in Breast Milk
Cmax was defined as maximum observed concentration of nirmatrelvir in breast milk.
Time frame: At Day -1 (24 Hours Prior to Dosing on Day 1), Pre-dose on Day 1, 0 to 2, 2 to 4, 4 to 8, 8 to 12, 12 to 24, 24 to 32, 32 to 40 and 40 to 48 Hours Post-dose on Day 2
Area Under the Concentration-Time Profile From Time Zero to End of Dosing Interval for Nirmatrelvir in Breast Milk
Area under the concentration curve for nirmatrelvir in breast milk from time 0 to end of dosing interval.
Time frame: At Day -1 (24 Hours Prior to Dosing on Day 1), Pre-dose on Day 1, 0 to 2, 2 to 4, 4 to 8, 8 to 12, 12 to 24, 24 to 32, 32 to 40 and 40 to 48 Hours Post-dose on Day 2
Terminal Half-Life of Nirmatrelvir in Breast Milk
The time measured for the breast milk nirmatrelvir concentration to decrease by one half.
Time frame: At Day -1 (24 Hours Prior to Dosing on Day 1), Pre-dose on Day 1, 0 to 2, 2 to 4, 4 to 8, 8 to 12, 12 to 24, 24 to 32, 32 to 40 and 40 to 48 Hours Post-dose on Day 2
The Average Steady State Concentration of Nirmatrelvir in Breast Milk
The average concentration across time and can be calculated by dividing AUCtau by time. AUCtau was defined area under the concentration curve from time 0 to end of dosing interval.
Time frame: At Day -1 (24 Hours Prior to Dosing on Day 1), Pre-dose on Day 1, 0 to 2, 2 to 4, 4 to 8, 8 to 12, 12 to 24, 24 to 32, 32 to 40 and 40 to 48 Hours Post-dose on Day 2
The Amount of Nirmatrelvir Excreted in Breast Milk Over the Dosing Interval Tau
The amount of nirmatrelvir excreted into breast milk over the dosing interval.
Time frame: At Day -1 (24 Hours Prior to Dosing on Day 1), Pre-dose on Day 1, 0 to 2, 2 to 4, 4 to 8, 8 to 12, 12 to 24, 24 to 32, 32 to 40 and 40 to 48 Hours Post-dose on Day 2
The Percent of Amount of Nirmatrelvir Excreted in Breast Milk Over The Dosing Interval Tau
The percent of nirmatelvir excreted in breast milk to amount of breast milk over the dosing interval .
Time frame: At Day -1 (24 Hours Prior to Dosing on Day 1), Pre-dose on Day 1, 0 to 2, 2 to 4, 4 to 8, 8 to 12, 12 to 24, 24 to 32, 32 to 40 and 40 to 48 Hours Post-dose on Day 2
Breast Milk Clearance of Nirmatrelvir
Clearance was defined as the apparent volume (Liter) of breast milk completely cleared the nirmatrelvir per hour.
Time frame: At Day -1 (24 Hours Prior to Dosing on Day 1), Pre-dose on Day 1, 0 to 2, 2 to 4, 4 to 8, 8 to 12, 12 to 24, 24 to 32, 32 to 40 and 40 to 48 Hours Post-dose on Day 2
The Maximum Observed Concentration of Ritonavir in Breast Milk Observed Over the Dosing Interval
The maximum observed concentration and was directly observed from data.
Time frame: At Day -1 (24 Hours Prior to Dosing on Day 1), Pre-dose on Day 1, 0 to 2, 2 to 4, 4 to 8, 8 to 12, 12 to 24, 24 to 32, 32 to 40 and 40 to 48 Hours Post-dose on Day 2
Time to Reach Cmax of Ritonavir in Breast Milk
Cmax was defined as maximum observed concentration of ritonavir in breast milk.
Time frame: At Day -1 (24 Hours Prior to Dosing on Day 1), 0 to 2, 2 to 4, 4 to 8, 8 to 12, 12 to 24, 24 to 32, 32 to 40 and 40 to 48 Hours Post-dose on Day 2
Area Under the Concentration-Time Profile for Ritonavir in Breast Milk From Time Zero to End of Dosing Interval
Area under the concentration curve for ritonavir in breast milk from time 0 to end of dosing interval.
Time frame: At Day -1 (24 Hours Prior to Dosing on Day 1), Pre-dose on Day 1, 0 to 2, 2 to 4, 4 to 8, 8 to 12, 12 to 24, 24 to 32, 32 to 40 and 40 to 48 Hours Post-dose on Day 2
Half-Life of Ritonavir in Breast Milk
The time measured for the breast milk ritonavir concentration to decrease by one half.
Time frame: At Day -1 (24 Hours Prior to Dosing on Day 1), Pre-dose on Day 1, 0 to 2, 2 to 4, 4 to 8, 8 to 12, 12 to 24, 24 to 32, 32 to 40 and 40 to 48 Hours Post-dose on Day 2
The Average Steady State Concentration of Ritonavir in Breast Milk
The average concentration across time and can be calculated by dividing AUCtau by time. AUCtau was defined area under the concentration curve from time 0 to end of dosing interval.
Time frame: At Day -1 (24 Hours Prior to Dosing on Day 1), Pre-dose on Day 1, 0 to 2, 2 to 4, 4 to 8, 8 to 12, 12 to 24, 24 to 32, 32 to 40 and 40 to 48 Hours Post-dose on Day 2
The Amount of Ritonavir Excreted in Breast Milk Over the Dosing Interval Tau
The amount of ritonavir excreted into breast milk over the dosing interval.
This platform is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.
Time frame: At Day -1 (24 Hours Prior to Dosing on Day 1), Pre-dose on Day 1, 0 to 2, 2 to 4, 4 to 8, 8 to 12, 12 to 24, 24 to 32, 32 to 40 and 40 to 48 Hours Post-dose on Day 2
The Percent of Ritonavir Excreted in Breast Milk Over The Dosing Interval Tau
The percent of ritonavir excreted in breast milk to amount of breast milk over the dosing interval.
Time frame: At Day -1 (24 Hours Prior to Dosing on Day 1), Pre-dose on Day 1, 0 to 2, 2 to 4, 4 to 8, 8 to 12, 12 to 24, 24 to 32, 32 to 40 and 40 to 48 Hours Post-dose on Day 2
Breast Milk Clearance of Ritonavir
Clearance was defined as the apparent volume (L) of breast milk completely cleared the ritonavir per hour.
Time frame: At Day -1 (24 Hours Prior to Dosing on Day 1), Pre-dose on Day 1, 0 to 2, 2 to 4, 4 to 8, 8 to 12, 12 to 24, 24 to 32, 32 to 40 and 40 to 48 Hours Post-dose on Day 2
The Maximum Observed Concentration of Nirmatrelvir in Plasma Observed Over the Dosing Interval
The maximum observed concentration and was directly observed from data.
Time frame: At 0, 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 18, 24, 32, 40, 48 Hours Post Dose on Day 2
The Maximum Observed Concentration of Ritonavir in Plasma Observed Over the Dosing Interval
The maximum observed concentration and was directly observed from data.
Time frame: At 0, 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 18, 24, 32, 40, 48 Hours Post Dose on Day 2
Area Under the Concentration-Time Profile for Nirmatrelvir in Plasma From Time Zero to End of Dosing Interval
Area under the concentration curve for nirmatrelvir in breast milk from time 0 to end of dosing interval.
Time frame: At 0, 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 18, 24, 32, 40, 48 Hours Post Dose on Day 2
Area Under the Concentration-Time Profile for Ritonavir in Plasma From Time Zero to End of Dosing Interval
Area under the concentration curve for ritonavir in plasma from time 0 to end of dosing interval.
Time frame: At 0, 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 18, 24, 32, 40, 48 Hours Post Dose on Day 2
Half-Life of Nirmatrelvir in Plasma
The time measured for the plasma nirmatrelvir concentration to decrease by one half.
Time frame: At 0, 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 18, 24, 32, 40, 48 Hours Post Dose on Day 2
Half-Life of Ritonavir in Plasma
The time measured for the plasma ritonavir concentration to decrease by one half.
Time frame: At 0, 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 18, 24, 32, 40, 48 Hours Post Dose on Day 2
The Minimum Plasma Concentration of Nirmatrelvir Observed Over the Dosing Interval
The minimum observed concentration and was directly observed from data.
Time frame: At 0, 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 18, 24, 32, 40, 48 Hours Post Dose on Day 2
The Minimum Plasma Concentration of Ritonavir Observed Over the Dosing Interval
The minimum observed concentration and was directly observed from data.
Time frame: At 0, 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 18, 24, 32, 40, 48 Hours Post Dose on Day 2
Time to Reach Cmax of Nirmatrelvir in Plasma
Cmax was defined as maximum observed concentration of nirmatrelvir in plasma.
Time frame: At 0, 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 18, 24, 32, 40, 48 Hours Post Dose on Day 2
Time to Reach Cmax of Ritonavir in Plasma
Cmax was defined as maximum observed concentration of ritonavir in plasma.
Time frame: At 0, 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 18, 24, 32, 40, 48 Hours Post Dose on Day 2
Apparent Clearance of Nirmatrelvir From Plasma
Clearance was defined as the apparent volume (L) of plasma completely cleared the nirmatrelvir per hour.
Time frame: At 0, 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 18, 24, 32, 40, 48 Hours Post Dose on Day 2
Apparent Clearance of Ritonavir From Plasma
Clearance was defined as the apparent volume (L) of plasma completely cleared the ritonavir per hour.
Time frame: At 0, 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 18, 24, 32, 40, 48 Hours Post Dose on Day 2
Apparent Volume of Nirmatrelvir Distribution
Volume of distribution was defined as the theoretical volume in which the total amount of drug would need to be uniformly distributed to produce the desired plasma concentration of a drug. Apparent volume of distribution after oral dose was influenced by the fraction absorbed.
Time frame: At 0, 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 18, 24, 32, 40, 48 Hours Post Dose on Day 2
Apparent Volume of Ritonavir Distribution
Volume of distribution was defined as the theoretical volume in which the total amount of drug would need to be uniformly distributed to produce the desired plasma concentration of a drug. Apparent volume of distribution after oral dose was influenced by the fraction absorbed.
Time frame: At 0, 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 18, 24, 32, 40, 48 Hours Post Dose on Day 2
The Average Steady State Concentration of Nirmatrelvir in Plasma
The average concentration across time and can be calculated by dividing AUCtau by time. AUCtau was defined area under the concentration curve from time 0 to end of dosing interval.
Time frame: At 0, 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 18, 24, 32, 40, 48 Hours Post Dose on Day 2
The Average Steady State Concentration of Ritonavir in Plasma
The average concentration across time and can be calculated by dividing AUCtau by time. AUCtau was defined area under the concentration curve from time 0 to end of dosing interval.
Time frame: At 0, 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 18, 24, 32, 40, 48 Hours Post Dose on Day 2
Daily (24 Hour) Amount of Nirmatrelvir Excreted in Breast Milk
Amount of nirmatrelvir excreted in breast milk in 24 hours.
Time frame: At Day -1 (24 Hours Prior to Dosing on Day 1), Pre-dose on Day 1, 0 to 2, 2 to 4, 4 to 8, 8 to 12, 12 to 24, 24 to 32, 32 to 40 and 40 to 48 Hours Post-dose on Day 2
Daily (24 Hour) Amount of Ritonavir Excreted in Breast Milk
Amount of ritonavir excreted in breast milk in 24 hours.
Time frame: At Day -1 (24 Hours Prior to Dosing on Day 1), Pre-dose on Day 1, 0 to 2, 2 to 4, 4 to 8, 8 to 12, 12 to 24, 24 to 32, 32 to 40 and 40 to 48 Hours Post-dose on Day 2
Milk to Plasma Ratio of Nirmatrelvir for AUCtau During Dosing Interval
The ratio of area under the concentration-time profile for nirmatrelvir in milk to those in plasma from time zero to end of dosing interval.
Time frame: At Day -1 (24 Hours Prior to Dosing on Day 1), Pre-dose on Day 1, 0 to 2, 2 to 4, 4 to 8, 8 to 12, 12 to 24, 24 to 32, 32 to 40 and 40 to 48 Hours Post-dose on Day 2
Milk to Plasma Ratio of Ritonavir for AUCtau During Dosing Interval
The ratio of area under the concentration-time profile for ritonavir in milk to those in plasma from time zero to end of dosing interval.
Time frame: At Day -1 (24 Hours Prior to Dosing on Day 1), Pre-dose on Day 1, 0 to 2, 2 to 4, 4 to 8, 8 to 12, 12 to 24, 24 to 32, 32 to 40 and 40 to 48 Hours Post-dose on Day 2
Milk to Plasma Ratio of Nirmatrelvir for Cmax During Dosing Interval
The ratio of the maximum concentration of nirmatrelvir in breast milk to those in plasma observed over the dosing interval.
Time frame: At Day -1 (24 Hours Prior to Dosing on Day 1), Pre-dose on Day 1, 0 to 2, 2 to 4, 4 to 8, 8 to 12, 12 to 24, 24 to 32, 32 to 40 and 40 to 48 Hours Post-dose on Day 2
Milk to Plasma Ratio of Ritonavir for Cmax During Dosing Interval
The ratio of the maximum concentration of ritonavir in breast milk to those in plasma observed over the dosing interval.
Time frame: At Day -1 (24 Hours Prior to Dosing on Day 1), Pre-dose on Day 1, 0 to 2, 2 to 4, 4 to 8, 8 to 12, 12 to 24, 24 to 32, 32 to 40 and 40 to 48 Hours Post-dose on Day 2
Body Weight Normalized Infant Dose (BWNID) of Nirmatrelvir in mg/kg/Day
BWNID = MPAUCtau \* Cav \* 150 mL/kg/day, where 150 mL/kg/day\^2 is the standardized milk consumption for an infant. MPAUCtau: Milk to plasma ratio for AUCtau. Cav: Average concentration.
Time frame: At Day -1 (24 Hours Prior to Dosing on Day 1), Pre-dose on Day 1, 0 to 2, 2 to 4, 4 to 8, 8 to 12, 12 to 24, 24 to 32, 32 to 40 and 40 to 48 Hours Post-dose on Day 2
BWNID of Ritonavir in mg/kg/Day
BWNID = MPAUCtau \* Cav \* 150 mL/kg/day, where 150 mL/kg/day\^2 is the standardized milk consumption for an infant. MPAUCtau: Milk to plasma ratio for AUCtau. Cav: Average concentration.
Time frame: At Day -1 (24 Hours Prior to Dosing on Day 1), Pre-dose on Day 1, 0 to 2, 2 to 4, 4 to 8, 8 to 12, 12 to 24, 24 to 32, 32 to 40 and 40 to 48 Hours Post-dose on Day 2
Body Weight Normalized Maternal Dose (BWNMD) of Nirmatrelvir in mg/kg/Day
Maternal dose in mg/day (300 mg BID = 600 mg/day for nirmatrelvir and 100 mg BID = 200 mg/day for ritonavir) / maternal weight in kg at screening.
Time frame: At Day -1 (24 Hours Prior to Dosing on Day 1), Pre-dose on Day 1, 0 to 2, 2 to 4, 4 to 8, 8 to 12, 12 to 24, 24 to 32, 32 to 40 and 40 to 48 Hours Post-dose on Day 2
BWNMD of Ritonavir in mg/kg/Day
Maternal dose in mg/day (300 mg BID = 600 mg/day for nirmatrelvir and 100 mg BID = 200 mg/day for ritonavir) / maternal weight in kg at screening.
Time frame: At Day -1 (24 Hours Prior to Dosing on Day 1), Pre-dose on Day 1, 0 to 2, 2 to 4, 4 to 8, 8 to 12, 12 to 24, 24 to 32, 32 to 40 and 40 to 48 Hours Post-dose on Day 2
Infant Dose Expressed As % of Body Weight Normalized Maternal Dose (BWNIDPCM) for Nirmatrelvir
BWNIDPCM = 100 \* BWNID / BWNMD.
Time frame: At Day -1 (24 Hours Prior to Dosing on Day 1), Pre-dose on Day 1, 0 to 2, 2 to 4, 4 to 8, 8 to 12, 12 to 24, 24 to 32, 32 to 40 and 40 to 48 Hours Post-dose on Day 2
BWNIDPCM for Ritonavir
BWNIDPCM = 100 \* BWNID / BWNMD.
Time frame: At Day -1 (24 Hours Prior to Dosing on Day 1), Pre-dose on Day 1, 0 to 2, 2 to 4, 4 to 8, 8 to 12, 12 to 24, 24 to 32, 32 to 40 and 40 to 48 Hours Post-dose on Day 2
Number of Participants With Treatment Emergent Adverse Events
An adverse event (AE) was any untoward medical occurrence in a participant or clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. AEs might arise from symptoms or other complaints reported to the investigator by the participant (or, when appropriate, by a caregiver, surrogate, or the participant's legally authorized representative), or they might arise from clinical findings of the investigator or other healthcare providers (clinical signs, test results, etc.). TEAEs were those with initial onset or increasing in severity after the first dose of study treatment.
Time frame: From the first dose of study treatment on Day 1 to up to 28 days after the last dose of study intervention on Day 2 (maximum to 30 days)
Number of Participants With Laboratory Abnormalities (Without Regard to Baseline Abnormality)
The laboratory abnormality parameters included urinalysis: urine bilirubin (\>=1), urine hemoglobin (\>=1) and leukocyte esterase (\>=1).
Time frame: At Screening (Day -28 to Day -2), Day -1, and Day 4
Number of Participants With Vital Signs Abnormalities
Single supine blood pressure (BP), and pulse rate (PR) were performed following approximately a 5-minute rest in a supine position. BP, and PR assessments will be performed after collection of electrocardiogram (ECGs) and prior to collection of blood draws if scheduled at the same time. Vital signs abnormality included supine systolic BP \<90mmHg.
Time frame: At Screening (Day -28 to Day -2), Pre-dose and 12 Hours post-dose on Day 1, Pre-dose and 48 Hours Post-dose on Day 2
Number of Participants With ECG Abnormalities
Standard 12-lead ECGs utilizing limb leads (with a 10 second rhythm strip) were collected. All ECG assessments were made after at least a 5-minute rest in a supine position and prior to any blood draws or vital sign measurements.
Time frame: At Screening (from Day -28 to Day -2)
Number of Participants With Physical Examination Abnormalities
Physical examination included height, weight and body mass index (BMI, BMI = weight \[kg\] / height \[m\^2\]) obtained for eligibility criteria. Physical examination abnormalities: BMI \<17.5 kg/m\^2; and a total body weight \<=50 kg (110 lb).
Time frame: At Screening (from Day -28 to Day -2) or Day -1