Pharmacokinetics and Bioequivalence Evaluation of Piracetam Tablet: A Randomized, Single-Dose, Two-Period, Crossover Study in Healthy Chinese Participants Under Fasting and Fed Conditions

Abstract

Background

Piracetam, a nootropic drug, is widely used for treating cognitive impairments. However, pharmacokinetic and bioequivalence data for piracetam formulations in the Chinese population are limited. This study was conducted to evaluate the pharmacokinetics and bioequivalence of a newly developed generic piracetam tablet compared with the reference product (Nootropyl^®) in healthy Chinese participants under fasting and fed conditions.

Methods

A randomized, open-label, single-dose, two-period, two-sequence crossover study was conducted in healthy Chinese participants under fasting and fed conditions. Healthy participants received a single oral dose of piracetam 800 mg as either the test or reference formulation, followed by a 7-day washout period. Plasma piracetam concentrations were determined using a validated high-performance liquid chromatography–tandem mass spectrometry method. Pharmacokinetic parameters, including maximum plasma concentration (C_max), area under the plasma concentration–time curve from time zero to the last measurable concentration (AUC_0–t), and area under the plasma concentration–time curve extrapolated to infinity (AUC_0–∞), were calculated using non-compartmental analysis. Bioequivalence was assessed by calculating the 90% confidence intervals (CIs) of the geometric mean ratios (GMRs) for C_max, AUC_0–t, and AUC_0–∞.

Results

56 participants were enrolled, with 28 participants completing each study under fasting and fed conditions. Under fasting conditions, the 90% confidence intervals (CIs) of the GMRs for C_max, AUC_0-t, and AUC_0-∞ were 98.53%, 98.40%, and 98.49%, respectively. Under fed conditions, the corresponding 90% CIs were 99.31%, 99.03%, and 99.01%. All values were within the predefined bioequivalence acceptance range of 80–125%. Food intake reduced the rate of absorption, as indicated by a lower C_max and delayed time to maximum concentration (T_max), without affecting the extent of absorption. Both formulations were well tolerated, and no serious adverse events were reported.

Conclusions

The test piracetam tablet was demonstrated to be bioequivalent to the reference formulation with respect to the rate and extent of absorption under both fasting and fed conditions in healthy Chinese participants. The comparable safety and tolerability profiles support the clinical interchangeability of the generic and reference piracetam formulations.

Clinical Trial Registration

CTR20213027.

Key Points

Pharmacokinetic and bioequivalence evidence for piracetam tablet formulations in the Chinese population remains limited, particularly under both fasting and fed conditions.

In this randomized, single-dose, crossover study, the test and reference piracetam tablets exhibited comparable pharmacokinetic profiles, with the 90% confidence intervals for maximum plasma concentration (Cmax), area under the plasma concentration–time curve from time zero to the last measurable concentration (AUC0–t), and AUC extrapolated to infinity (AUC0–∞) fully within the accepted bioequivalence range.

Food intake significantly delayed the absorption rate of piracetam, as reflected by reduced Cmax and prolonged time to Cmax (Tmax), without altering the extent of systemic exposure, and both formulations demonstrated favorable tolerability.

Introduction

Piracetam (2-oxo-1-pyrrolidineacetamide) is a cyclic derivative of γ-aminobutyric acid (GABA), originally synthesized by Giurgea in UCB Laboratories in Belgium. It was the first representative “nootropic” drug and has been in clinical use since 1972 [1]. Piracetam has been widely used for the treatment of age-related mental impairments [2], cerebral ischemia-induced short-term memory/cognitive deterioration after heart bypass surgery [3], neuroprotective [4], chronic cerebrovascular disorders [5], myoclonic epilepsy [6], sickle cell anemia [7], posture and gait disturbances [8], stroke/ischemia [9], breath-holding spells [10], and memory impairment [11, 12]. Although the exact mechanism of action has not been fully elucidated, piracetam has been demonstrated to influence neuronal and vascular functions. At a neuronal level, piracetam modulates neurotransmission in a range of transmitter systems (including cholinergic and glutamatergic), has neuroprotective and anticonvulsant properties, and improved neuroplasticity [13–15]. At a vascular level, it appears to enhance microcirculation by reducing platelet activity, enhancing red blood cell deformability and reducing adherence of damaged erythrocytes to endothelial cells [16, 17].

Piracetam is rapidly and almost completely absorbed after oral administration, exhibiting an oral bioavailability close to 100%, with peak plasma concentrations typically reached within 30–40 minutes and a terminal elimination half-life of 5–6 hours. But the elimination half-life of the drug may be increased in elderly patients, particularly those with multiple disease states. The drug is excreted unchanged in the urine, urinary excretion accounting for > 98% of the administered dose. Distribution studies have shown that the drug is able to cross the blood–brain barrier, and preferentially concentrate in the grey matter of the cerebrum and cerebellum, caudate nucleus, hippocampus, lateral geniculate body, and choroid plexus [18]. Piracetam is generally reported to be well tolerated and free from adverse effects. Occasional reported side effects include nervousness, anxiety, insomnia, agitation, mild dizziness, hyperkinesia, and tremor. The dosing of piracetam varies according to indication.

However, information from pharmacokinetic (PK) studies of the Chinese population are limited. Consistent with the National Medical Products Administration (NMPA) guidelines, this study compared the PK parameters of the generic piracetam tablet at 800 mg with that of the original product (Nootropyl^®). To support the marketing approval of the newly developed generic formulation by China Resources Double-Crane Limin Pharmaceutical Co., Ltd (Jinan, China), a bioequivalence study was performed in healthy Chinese participants under fasting and fed conditions.

Methods

Ethics

The study was registered at the Drug Trial Registration and Information Publishing platform in China (www.chinadrugtrials.org.cn: CTR20213027). The study protocol and informed consent forms were reviewed and approved by the independent ethics committee of Wuhan Pulmonary Hospital [Ethics Number: 2021-019]. This study was conducted in compliance with the ethical principles of the Declaration of Helsinki, the International Conference on Harmonization Good Clinical Practice, and guidelines recommended by the China National Medical Products Administration. The participants were free to withdraw from the study at any time.

Study Drugs

The 800-mg piracetam tablet formulation used as the test product (T) was provided by China Resources Double-Crane Limin Pharmaceutical Co., Ltd, Jinan, China (batch number: 02106203; expiry date: May 2023). Meanwhile, the reference product (R) was manufactured by UCB Pharma SA (Nootropyl^®; batch number: 306471; expiry date: February 2024), which was also provided by China Resources Double-Crane Limin Pharmaceutical Co., Ltd. In each treatment period, each participant received the test or reference formulation of piracetam tablet 800 mg.

Participants

All participants signed informed consent forms (ICFs) after a full understanding of the study’s purpose, content, procedures, and potential risks. Eligible participants needed to meet the following basic criteria in the screening period: male and female participants aged between 18 and 65 years old, with weight > 50 kg and > 45 kg, respectively, and with body mass index (BMI) in the range of 19–27 kg/m². After signing ICFs, all participants underwent a series of inquiries and examinations, including examination of demographic data, past medical history, vital signs, physical examination, chest radiography, 12-lead electrocardiography, and clinical laboratory tests (containing routine analysis of the blood, routine urinalysis, coagulation function, immunological examination for hepatitis B surface antigen, hepatitis C antibody, syphilis antibody, human immunodeficiency virus antibody, liver function, and renal function). If these examination results were normal, or abnormal but clinically insignificant, judged by researchers, participants were considered healthy and allowed to participate in this study.

However, participants were excluded if they had any history or evidence of the following: (1) allergic constitution, especially allergy to any ingredient in the piracetam tablet; (2) diseases of the nervous system, the cardiovascular system, the blood system, the immune system, the urinary system, the respiratory system, etc.; (3) history of donation or acute loss of blood (more than 200 mL) in the past 3 months; (4) smoking more than five cigarettes per day within 3 months prior to screening; (5) consumption of more than eight cups (250 mL per cup) of tea, coffee, or caffeinated beverages per day within 3 months prior to screening; (6) consumption of more than 14 units of alcohol per week (1 unit is 360 mL of beer or 45 mL of liquor of 40% alcohol, or 150 mL of wine) within 3 months prior to screening; (7) intolerance to intravenous indwelling needles or blood phobia; (8) dietary requirements that prevented compliance with the provided regulations; (9) enrollment in any drug clinical trial within 3 months prior to screening; (10) abnormal results of vital sign assessments, physical examination, electrocardiogram, and other laboratory examination that were clinically significant.

Meanwhile, female participants who were pregnant or lactating during the study period, or planned pregnancy 1 month before dosing to 6 months after the end of the study were excluded.

Study Design

This study was a randomized, open-label, single-dose, two-sequence, two-period, crossover bioequivalence study in healthy Chinese participants performed at the Phase I Clinical Research Center of Wuhan Pulmonary Hospital. The trial consisted of two separate studies (one under fasting conditions and another under fed conditions). All participants in each trial were randomly assigned to the TR or RT group at a 1:1 ratio according to a random number table generated by SAS statistical software (v9. 4). Group TR participants received the test product in the first treatment period and received the reference product in the second treatment period, whereas Group RT had the opposite administration sequence. There was a 7-day washout period between the two treatment periods. The eligible participants were admitted to the Phase I Research Center 1 day prior to drug administration and underwent a fasting period of 10 h. Under a fasting state, each participant received a single dose of the test or reference tablet, administered orally with 240 mL of warm water, whereas participants under the fed state received a standard high-fat breakfast 30 min before each drug administration and followed the same scheme. Within 1 h before and after the dose application, water intake was prohibited. The participants were provided with lunch and dinner 4 h and 10 h after administration, respectively. Safety assessments were conducted during the study period.

Sample Size

According to the within-subject variability of piracetam, we comprehensively evaluated how many periods of cross-over tests should be carried out. Based on a previous report, the individual variation in piracetam was 19.76% [19]. Hence, we adopted the study design of a two-period crossover in the fasting and fed states, respectively. In terms of sample size estimation, the coefficient of intra-individual variation of maximum plasma concentration (C_max) and area under the plasma concentration–time curve extrapolated to infinity (AUC_0–∞) for piracetam was set at 22% in two trials. Whether in the fasting study or the fed study, assuming a one-sided test with α = 0.05, and power of 0.8, the geometric mean ratios of the test and reference formulations were expected to be 0.95, and 90% CI of 80–125% for bioequivalence. Twenty-two participants were required for the fasting and fed trials, respectively. After considering the dropout rate, 28 participants were enrolled for each trial. A total of 56 participants were recruited and enrolled in this study.

Blood Sampling

Vacuum tubes (4 mL) with EDTA-K2 anticoagulant were used to collect blood samples for detecting plasma concentrations. The time points for blood sample collection for the two trials were slightly different. In the fasting study, the time points for blood sample collection were 0 h (within 1 h before administration), 0.17, 0.33, 0.5, 0.75, 1.0, 1.33, 1.67, 2.0, 2.5, 3.0, 4.0, 5.0, 6.0, 8.0, 10.0, 12.0, 24.0 h after administration. In the fed study, the time points for blood collection were 0 h (within 1 h before administration), 0.25, 0.5, 0.75, 1.0, 1.33, 1.67, 2.0, 2.33, 2.67, 3.0, 3.5, 4.0, 6.0, 8.0, 10.0, 12.0, 24.0 h after administration. The blood samples were centrifuged at 1700g for 10 min at 4 ℃ within 1 h of collection. The plasma samples were then obtained from the supernatants and stored at − 80 ℃ until use within 24 h.

Bioanalytical Method

Plasma concentrations of piracetam were quantified using a validated high-performance liquid chromatography–tandem mass spectrometry (HPLC-MS/MS). Chromatographic analysis was conducted on a Shimadzu LC system (LC-20ADXR, Shimadzu, Japan) coupled with an AB Sciex Triple Quad™ 4500 mass spectrometer equipped with a Turbo Spray ion source. Data acquisition and processing were carried out using Analyst software (version 1.6.3, AB Sciex). Separation was achieved on a Shim-pack Velox HILIC column (2.7 μm, 3.0 × 100 mm, Shimadzu, Japan). The mobile phase consisted of water containing 0.1% formic acid (Phase A) and acetonitrile (Phase B), delivered at a flow rate of 0.700 mL/min. The column temperature was maintained at 35 ℃.

For mass analysis, ionization was achieved using electrospray ionization (ESI) in positive mode, and detection was performed in multiple reaction monitoring (MRM) mode. The monitored precursor-to-product ion transitions were m/z 143.1→98.1 for piracetam and m/z 149.1 → 104.1 for piracetam-d6, with a dwell time of 100 ms. Piracetam-d6 was used as a stable isotope-labeled internal standard (IS).

Calibration curves were linear over the concentration range of 100–40,000 ng/mL, with the lower limit of quantification (LLOQ) established at 100 ng/mL. Regression analysis was performed using weighted (1/x²) least-squares linear fitting. The method was comprehensively validated for selectivity, precision, accuracy, recovery, and stability, meeting regulatory acceptance criteria (RSD ≤ 15%, ≤ 20% at LLOQ). These validation results demonstrated that the method was reliable and suitable for quantitative determination of piracetam in human plasma samples in this study.

Pharmacokinetic and Statistical Analysis

Based on the plasma concentration data, the PK parameters of piracetam were calculated using a non-compartmental model using Phoenix WinNonlin software (version 8.3). C_max and time to maximum plasma concentration (T_max) were determined directly from the observed plasma concentration–time profiles. Area under the plasma concentration–time curve from time zero to the last measurable concentration (AUC_0–t) was calculated using the linear trapezoidal method. AUC_0–∞ was calculated as AUC_0–∞ = AUC_0–t + Ct/λz, where Ct was the last detectable concentration and λz was the elimination rate constant. λz was determined by using linear least-squares regression analysis of the concentration–time data obtained from the terminal log-linear phase. Terminal half-life T_½ was calculated to be 0.693/λz.

After the transformation of C_max, AUC_0–t, and AUC_0–∞ to their natural logarithmic values, analysis of variance (ANOVA) was performed using a linear mixed model to evaluate the effects of formulation, trial period, dosing sequence, and participants. The bioequivalence was evaluated by calculating the 90% CIs of the geometric mean ratios (GMRs) of the test formulation to reference formulation. The acceptance criteria for bioequivalence were that 90% of CIs were completely within the range of 80.00–125.00% for C_max, AUC_0–t, and AUC_0–∞. Nonparametric tests was used to analyze the T_max between the two formulations.

Safety Assessment

During the study, safety was evaluated by various measures, including physical examination, body vital examination, 12-lead electrocardiography (ECG), and clinical laboratory tests. Vital signs (body temperature, heart rate, and blood pressure) were monitored at screening, before drug administration (within 1 h), and at 1, 2, 4, 12, and 24 hours after administration in each treatment period. Clinical laboratory tests, physical examination and 12-lead ECG were conducted at screening and before removal from the study. For standardization of the AE report, we coded all AEs using terms from the Medical Dictionary of Regulatory Activities (MedDRA^®) and graded the severity of these AEs according to the Common Terminology Criteria for Adverse Events (CTCAE, version 5.0) published by the National Cancer Institute of the United States.

Results

Study Population

This study was conducted between November 26, 2021, and December 30, 2021. Figure 1 shows the study design and disposition of participants in the two trials. In total, 112 potential Chinese adult participants were screened. Of these, 56 healthy participants met the enrollment criteria for the protocol and were selected for the fasting and fed studies (n = 28 per study). Table 1 summarizes the demographic characteristics of all participants. The sex, age, weight, height, and BMI of participants were similar between the two parts of the study. Under fasting and fed conditions, all participants completed the treatment periods.

Fig. 1.

Study design and disposition of participants

Table 1.

Demographic characteristics of the healthy participants

Variable	Fasting condition (n = 28)	Fed condition (n = 28)
Sex
Male (%)	22 (78.57)	21 (75)
Female (%)	6 (21.43)	7 (25)
Age, years
Mean (SD)	29.4 (6.39)	27.6 (4.45)
Min–max	18–40	18–40
Height, cm
Mean (SD)	168.68 (7.62)	168.43 (8.09)
Min–max	152.5–180.5	152.0–182.0
Weight, kg
Mean (SD)	64.35 (7.12)	64.83 (7.04)
Min–max	52.7–80.2	55.6–80.4
BMI, kg/m2
Mean (SD)	22.58 (1.4)	22.86 (2.0)
Min–max	19.5–24.6	19.5–24.6
Ethnicity
Han Chinese (%)	22 (78.57%)	28 (100.00)
Others	6 (21.43%)	0 (0.00)

BMI body mass index, max maximum, min minimum, SD standard deviation

Pharmacokinetics and Bioequivalence

All PK parameters were analyzed based on the pharmacokinetics concentration set (PKCS) and pharmacokinetics parameter set (PKPS). In the fasting study, the data of 28 enrolled participants were entered into pharmacokinetics analysis. Figure 2 shows the mean plasma concentration–time curves of the two formulations under fasting conditions. The disposition of the two plasma concentration–time curves is similar. The primary pharmacokinetic parameters are listed in Table 2. For the test or reference formulations, C_max were 31,678.6 ± 7209.7 and 32,117.9 ± 7645.1 ng/mL, AUC_0–t were 151,444.6 ± 16,249.4 and 154,123.1 ± 18,472.7 ng.h/mL, AUC_0–∞ were 159,790.6 ± 16,653.3 and 162,479.2 ± 19,130.9 ng.h/mL, and t_½ were 5.8 ± 0.7 and 5.8 ± 0.6 h, respectively. The results of bioequivalence assessment of the fasting study are shown in Table 3. The 90% CIs of the GMRs of the test to the reference formulation were 90.85–106.85% for C_max, 96.78–100.05% for AUC_0-t, and 96.77–100.24% for AUC_0–∞. The 90% CIs were within the accepted bioequivalence range of 80.00–125.00%, which suggested that the test and reference products of piracetam exhibited bioequivalence under fasting conditions. The intra-subject CV% for C_max, AUC_0–t, and AUC_0–∞ were 17.93%, 3.64%, and 3.87%, respectively, indicating that piracetam has no high variability from the perspective of pharmacokinetics. The powers of C_max, AUC_0–t, and AUC_0–∞ were nearly 100%, proving that our expected sample size is sufficient and reasonable.

Fig. 2.

Linear (A) and semi-logarithmic (B) of mean plasma concentration–time profiles for the test and reference formulations after a single 800-mg dose of piracetam tablet in healthy participants under fasting condition. N = 28. The dotted lines represent bars, bars represent SD. R reference formulation, SD standard deviation, T test formulation

Table 2.

Pharmacokinetic parameters of piracetam after a single 800-mg dose of test and reference piracetam tablet in healthy Chinese participants under fasting and fed conditions

Pharmacokinetic parameters	Fasting condition (N = 28)		Fed condition (N = 28)
	Test (n = 28)	Reference (n = 28)	Test (n = 28)	Reference (n = 28)
Tmax (h)	0.5 (0.3, 1.3)	0.5 (0.3, 1.7)	1.7 (0.8, 6)	1.7 (0.5, 6)
Cmax (ng/mL)	31,678.6 ± 7209.7	32,117.9 ± 7465.	20,442.9 ± 3643.2	20,775.0 ± 4810.9
AUC0–t (ng.h/mL)	151,444.6 ± 16,249.4	154,123.1 ± 18,472.7	140,505.8 ± 15,972.5	141,755.7 ± 15,066.1
AUC0–∞ (ng.h/mL)	159,790.6 ± 16,653.3	162,479.2 ± 19,130.9	149,739.0 ± 19,752.3	150,995.8 ± 18,173.4
t½ (h)	5.8 ± 0.7	5.8 ± 0.6	5.9 ± 1.1	5.9 ± 1.0
ℷz (h-1)	0.12 ± 0.01	0.12 ± 0.01	0.12 ± 0.02	0.12 ± 0.02

All values are expressed as mean ± SD except for T_max values, which are expressed as median (minimum, maximum)

AUC_0–t area under the plasma concentration–time curve from time 0 to the time of the last measurable concentration, AUC_0–∞ area under the plasma concentration–time curve from time 0 to infinity, C_max maximum plasma drug concentration, N the pharmacokinetic analysis set population, n the statistical analysis population, T_max time to reach C_max, t_½ terminal half-life, ℷz terminal elimination rate

Table 3.

Bioequivalence assessment of pharmacokinetic parameters of piracetam after a single 800-mg dose of test and reference piracetam tablets in healthy Chinese participants under fasting condition

Parameters	Fasting condition (N = 28)
	T	R	T/R (%)	90% CI	Intra-subject CV (%)	Power (%)
ln(Cmax)	30,885.86	31,346.46	98.53	90.85–106.85	17.93	99.70
ln(AUC0–t)	150,609.44	153,056.92	98.40	96.78–100.05	3.64	100.00
ln(AUC0–∞)	158,955.56	161,391.78	98.49	96.77–100.24	3.87	100.00

AUC_0–t area under the plasma concentration–time curve from time 0 to the time of the last measurable concentration, AUC_0–∞ area under the plasma concentration–time curve from time 0 to infinity, CI confidence interval, C_max maximum plasma drug concentration, CV coefficients of variation, N the bioequivalent analysis set population, R reference product, T test product

In the fed study, the data of 28 enrolled participants were entered into the pharmacokinetics analysis. Figure 3 shows the mean plasma concentration–time curves of the two formulations under fed conditions. The disposition of the two plasma concentration–time curves is also similar. The primary pharmacokinetic parameters are summarized in Table 2. For the test or reference formulations, C_max were 20,442.9 ± 3643.2 and 20,775.0 ± 4810.9 ng/mL, AUC_0–t were 140,505.8 ± 15,972.5 and 141,755.7 ± 15,066.1 ng.h/mL, AUC_0–∞ were 149,739.0 ± 19752.3 and 150,995.7 ± 18,173.4 ng.h/mL, and t_½ were 5.9 ± 1.1 and 5.9 ± 1.0 h. The results of bioequivalence assessment of the fed study are shown in Table 4. The 90% CIs of the GMRs of the test to the reference formulation were 93.58–105.39% for C_max, 97.70–100.37% for AUC_0–t, and 97.63–100.41% for AUC_0–∞, which were also within the accepted bioequivalence range of 80.00–125.00%. The results indicated that the test and reference products of piracetam were considered bioequivalent under fed conditions. The intra-subject CV% for C_max, AUC_0–t, and AUC_0–∞ were 13.10%, 2.96%, and 3.08%, respectively, which further showed that piracetam does not show high variability, regardless of fasting or fed conditions.

Fig. 3.

Linear (C) and semi-logarithmic (D) of mean plasma concentration–time profiles for the test and reference formulations after a single 800-mg dose of piracetam tablet in healthy participants under fed condition. N = 28. The dotted lines represent bars, bars represent SD. R reference formulation, SD standard deviation, T test formulation

Table 4.

Bioequivalence assessment of pharmacokinetic parameters of piracetam after a single 800-mg dose of test and reference piracetam tablets in healthy Chinese participants under fed condition

Parameters	Fed condition (N = 28)
	T	R	T/R (%)	90% CI	Intra-subject CV (%)	Power (%)
ln(Cmax)	20,112.12	20,252.02	99.31	93.58–105.39	13.10	100.00
ln(AUC0–t)	139,600.18	140,970.84	99.03	97.70–100.37	2.96	100.00
ln(AUC0–∞)	148,448.63	149,932.58	99.01	97.63–100.41	3.08	100.00

AUC_0–t area under the plasma concentration–time curve from time 0 to the time of the last measurable concentration, AUC_0–∞ area under the plasma concentration–time curve from time 0 to infinity, CI confidence interval, C_max maximum plasma drug concentration, CV coefficients of variation, N the bioequivalent analysis set population, R reference product, T test product

A general linear model was employed, with administration sequence, administration period, and formulation factor as fixed effects, and subjects nested within sequences as random effect. Multivariate analysis of variance (ANOVA) was separately performed on the logarithmically transformed values of C_max, AUC_0–t, and AUC_0–∞ of piracetam following the administration of the test or reference formulation. Table 5 shows analysis of variance of the pharmacokinetic parameters. In the fasting study, no formulation or period effect were found for C_max, AUC_0–t, and AUC_0–∞. There was significant difference in AUC_0–t and AUC_0-∞ among the administration sequence. In the fed study, the p value of administration period about AUC_0-∞ was < 0.05, with statistical significance. There was significant difference in AUC_0–t and AUC_0–∞ among the administration sequence. C_max, AUC_0–t, and AUC_0–∞ had no statistical difference as to formulation factor.

Table 5.

Analysis of variance of the pharmacokinetic parameters

Main factors	P (Fasting condition)			P (Fed condition)
	Ln Cmax	Ln AUC0–t	Ln AUC0–∞	Ln Cmax	Ln AUC0–t	Ln AUC0–∞
Administration period	0.2486	0.0900	0.0900	0.9563	0.0806	0.0196
Formulation factor	0.7581	0.1095	0.1095	0.8440	0.2280	0.2374
Administration sequence	0.8238	0.0015	0.0015	0.4421	0.0000	0.0000
Subjects sequence	0.0189	0.0000	0.0000	0.0002	0.0000	0.0000

AUC_0–t area under the plasma concentration–time curve from time 0 to the time of the last measurable concentration, AUC_0–∞ area under the plasma concentration–time curve from time 0 to infinity, C_max maximum plasma drug concentration

Safety Assessment

The safety and tolerability of piracetam were assessed based on the safety analysis set (SS) in which all participants received at least one dose of the study drug. A total of 28 participants were included in the fasting study, in which five AEs for two participants were reported with the reference product, and the incidence of AEs was 7.14% (2/28). All AEs were reported as grade 1 and spontaneously resolved without any specific treatment; one participant had anemia in period 2 of the T-R group; one participant had anemia, leukocyte count increase, neutrophil count increase, and percentage of neutrophil increase in period 2 of the T-R group. The investigators determined that these adverse reactions were unrelated to the study drug. In the fed study, five AEs occurred in five participants with an incidence of 17.86% (5/28). The intensity of all AEs was mild and all were reported as grade 1, which was judged to be unrelated to the study drug. AEs included blood uric acid increase, positive urine leukocyte, leukocyte count decrease, and anemia. All AEs resolved without the need for treatment, and the participants did not receive any intervention. No serious AEs occurred in either study. These safety results show that piracetam had good safety and was well tolerated in healthy participants under fasting and fed conditions. Table 6 summarizes the incidence of AEs with piracetam.

Table 6.

Summary of adverse events in healthy Chinese participants under fasting and fed conditions

Parameter	Fasting condition						Fed condition
	Test (n = 28)		Reference (n = 28)		Total (n = 28)		Test (n = 28)		Reference (n = 28)		Total (n = 28)
	AE count	N (%)	AE count	N (%)	AE count	N (%)	AE count	N (%)	AE count	N (%)	AE count	N (%)
Adverse events	0	0	5	2 (7.14)	5	2 (7.14)	1	1 (3.57)	4	4 (14.29)	5	5 (17.86)
Serious adverse events	0	0	0	0 (0)	0	0 (0)	0	0 (0)	0	0 (0)	0	0 (0)
Blood and lymphatic system disorders
Anemia	0	0	2	2 (7.14)	2	2 (7.14)	0	0	1	1 (3.57)	1	1 (3.57)
Results of inspection
Leukocyte count increased	0	0	1	1 (3.57)	1	1 (3.57)	0	0 (0)	0	0 (0)	0	0 (0)
Neutrophil count increased	0	0	1	1 (3.57)	1	1 (3.57)	0	0 (0)	0	0 (0)	0	0 (0)
Percentage of neutrophil increased	0	0	1	1 (3.57)	1	1 (3.57)	0	0 (0)	0	0 (0)	0	0 (0)
Blood uric acid increased	0	0	0	0 (0)	0	0 (0)	0	0	1	1 (3.57)	1	1 (3.57)
Positive urine leukocyte	0	0	0	0 (0)	0	0 (0)	0	0	1	1 (3.57)	1	1 (3.57)
Leukocyte count decreased	0	0	0	0 (0)	0	0 (0)	1	1 (3.57)	1	1 (3.57)	2	2 (7.14)

AE adverse event

Discussion

Piracetam was the first drug of the racetam group to be identified, and it is typically used to treat dementia caused by Alzheimer’s and other neurodegenerative diseases associated with aging, decreased cognitive ability and memory [20]. However, there is relatively little public information on the pharmacokinetics of piracetam tablets, especially among Chinese people. Through a literature search, we found that only one related article has been published [21]. The present study fully compared and evaluated the pharmacokinetics and bioequivalence between the test product and the reference product of piracetam tablet in healthy Chinese participants under fasting and fed conditions.

Comparing the primary pharmacokinetics parameters of piracetam with previous studies, the C_max, T_max, and AUC values for piracetam in this study were similar to those previously reported in a Brazilian population [19], but were different from those previously reported in the literature for the same dose in a Chinese population [21]. In our study, C_max and AUC were significantly higher after oral administration. This may be related to the different formulation of the reference product. In the reported study [21], a 400-mg formulation and a non-originator manufacturer's formulation were used as the reference products.

Furthermore, we compared the pharmacokinetic profiles of piracetam under fasting and fed conditions in the two studies. Table 2 shows clearly that food does not affect the extent of absorption of piracetam, although it does decrease the C_max of the drug by 35%, and T_max was delayed from 0.5 to 1.7 h, regardless of the use of test or reference formulation. This observation is clinically relevant and consistent with the known physiological impact of high-fat meals on gastrointestinal motility. High-fat and high-calorie food may slow gastric emptying and prolong the residence time of the drug in the stomach, thereby delaying its delivery to the small intestine, where absorption predominantly occurs [22]. As a result, the absorption rate of piracetam is reduced, leading to a lower C_max and a delayed T_max. However, since piracetam is highly soluble and almost completely absorbed, the total exposure (AUC) is not substantially affected by food intake. These findings suggest that although piracetam may be administered with or without food, clinicians should be aware that food can decrease the rate of absorption and delay onset of peak concentration, which may be relevant in situations where rapid therapeutic effects are desired.

Piracetam is remarkably well tolerated. In this study, no suspicious unexpected serious adverse reactions or serious adverse events occurred, and it is considered that the safety between the test formulation and the reference formulation are comparable.

However, several limitations should be noted in this study. Firstly, the study was conducted in a relatively small sample of healthy participants, which may limit the generalizability of the findings to broader populations, especially patients with comorbidities or those in specific age groups. Additionally, the study was restricted to a single-dose, crossover design under fasting and fed conditions, which does not account for long-term usage or repeated dosing effects. The impact of piracetam's pharmacokinetics in special populations, such as the elderly, patients with renal or hepatic impairments, or those on polypharmacy regimens, remains unclear and warrants further investigation. Furthermore, the absence of a comparison with other formulations or a dose-ranging study might limit the understanding of its behavior across various dosage levels and different drug forms. Finally, while the study assessed safety within the clinical trial period, long-term safety data remain insufficient, particularly regarding the potential for chronic use in a clinical setting.

Conclusion

Based on the results of this study, piracetam tablets in China are bioequivalent to the reference formulation (Nootropyl^®) in terms of the rate and extent of absorption under fasting and fed conditions. Both formulations were generally well tolerated in the healthy Chinese population and can be used interchangeably in the clinic to relieve the economic burden on Chinese patients.

Funding

This study was funded by China Resources Double-Crane Limin Pharmaceutical Co., Ltd (Jinan, China).

Declarations

Conflict of interest

LQY is a member of the research group from China Resources Double-Crane Limin Pharmaceutical Co., Ltd (Jinan, China), he declares no competing interests. HCP is a member of the research group from China Resources Double-Crane Limin Pharmaceutical Co., Ltd (Jinan, China), he declares no competing interests. WQH is a member of the research group from China Resources Double-Crane Limin Pharmaceutical Co., Ltd (Jinan, China), he declares no competing interests. All other authors declare no competing interests.

Ethics approval

This study was performed abiding by the Declaration of Helsinki, Good Clinical Practice (GCP), and guidelines of the China National Medical Products Administration (NMPA). The protocol, informed consent, and other relevant documents were approved by the independent ethics committee of Wuhan Pulmonary Hospital.

Consent to participate

Written informed consent was obtained from all participants prior to their enrollment in the study.

Consent for publication

All researchers, participants, institutions and the sponsors have agreed to publish the results of this study in this journal.

Availability of data and materials

The datasets used and/or analyzed for the current study are available from the corresponding authors upon reasonable request.

Code availability

Not applicable.

Author contributions

LG participated in the conception and design and contributed to quality control throughout the study. YHG contributed to the writing of the manuscript. ZM contributed to the study organization and implementation. PY and LXW were in charge of the management of study drugs. PZX, WJ, and XYF were responsible for disposition of biological samples. As the sponsor-affiliated authors, LQY, HCP, and WQH were involved only in study coordination and administrative support. All authors read and approved the final manuscript.