Neonatal seizures are one of the most challenging problems for experts across the globe. Although there is no consensus on the “ideal” treatment of neonatal seizures, phenobarbitone has been the drug of choice for decades. Unfortunately, although extensively studied in adults and children, levetiracetam lacks rigorous evaluation in the neonatal population, despite its frequent use as an off-label drug. The objective of this open-label, randomized, active-control, single-center, pragmatic trial was to compare the effectiveness of levetiracetam with phenobarbitone for term asphyxiated infants as a first-line drug.
The participants included in this study were inborn term asphyxiated infants with seizures in the first 48 hours of life. Infants satisfying the inclusion criteria were randomized to receive levetiracetam (20 mg/kg) or phenobarbitone (20 mg/kg). Clinical seizure control was noted. Infants who failed to respond to the primary drug were given the other group drug.
Of 103 eligible infants, 82 were randomly assigned (44 levetiracetam group, 38 phenobarbitone group). Clinical seizure control with the primary drug and maintenance of the same for 24 hours was observed in 29 infants (65.9%) in the levetiracetam group and 13 infants (34.2%) in the phenobarbitone group (P < .05, relative risk 0.52, 95% confidence interval 0.32–0.84). Of the infants in the phenobarbitone group who did not respond to the primary drug, 57.8% were controlled after adding levetiracetam.
Levetiracetam can be used with effectiveness as a first- and second-line drug in asphyxiated term infants. A more extensive study on pharmacokinetics and optimal regimen is required.
Neonatal seizures are some of the most challenging problems for experts across the globe. The neonatal period is the most vulnerable period for developing seizures, particularly during the first 1 to 2 days of life.1 Although relatively short-lasting, they can lead to dire consequences and pose a neurologic emergency in the NICU.
Birth asphyxia is a common cause of neonatal mortality and morbidity. It is caused by a compromised placental or pulmonary gas exchange secondary to an antepartum, intrapartum, peripartum, or postpartum insult. The resultant ischemia, acidosis, and hypercapnia lead to cell injury and subsequent compromise in the function of various organ systems. Hypoxic and ischemic injury in the brain can result in encephalopathy with clinical manifestations ranging from mild sensorium and tone changes to seizures, coma, and even respiratory failure and death. Perinatal asphyxia accounts for 19.2% of neonatal deaths in India.2 The resultant hypoxic-ischemic brain injury is one of the most common causes of neonatal seizures in term newborns in the first week of life. Although there is no consensus on the ideal treatment of neonatal seizures, phenobarbitone has been the drug of choice across centers for decades.3 However, the efficacy of phenobarbitone, as revealed in previous reports, is only ∼33% to 77%.4,5 Recent reports suggesting the role of phenobarbitone in neuronal apoptosis6 have made it essential to find a better alternative. Also, the accompanying hepatic injury in asphyxia makes the phenobarbitone serum levels unpredictable and may manifest as exaggerated adverse effects.
Although extensively studied in adults and children, levetiracetam lacks rigorous evaluation in the neonatal population, despite its frequent use as an off-label drug. It is postulated to act by binding to the synaptic vesicle protein SV2A7 with some putative action on GABA mediated inhibition8 and calcium channels.9 Recently, the authors of a few studies have reported levetiracetam as a safe drug with decent efficacy in newborns with an additional neuroprotective and cardioprotective role in asphyxiated infants.10 However there is a need for more evidence because most of the data are derived from case series, the results are inconsistent, and optimal dosage and regimen have not been established.11–13
A recently published, well-designed, multicenter, blinded, randomized trial, NEOLEV2,14 evaluated the efficacy of levetiracetam compared with phenobarbitone as a first-line treatment of neonatal seizures using video EEG both for diagnosis and to monitor the response to treatment. The authors found that phenobarbitone had much higher efficacy (80% vs 28%), although with a higher rate of adverse effects. However, seizures secondary to hypoxic-ischemic encephalopathy (HIE) contributed to approximately half of the total sample, and all the HIE infants received therapeutic hypothermia.14 Seizure epidemiology, etiology, diagnosis, and management in low-middle-income countries (LMICs) differs from high-income countries (HICs). The incidence of neonatal seizures is estimated to be 1 to 3 per 1000 live births in the HICs and varies from 36 to 90 per 1000 live births in LMICs.15 Although HIE is a major contributor to both HIC and LMIC, the incidence is much more in the LMICs. The recent HELIX trial postulates that the timing of insult and thus the response to treatment may differ in infants in the developing world.16,17 Infections have been reported as the second most common cause of seizures. Intracranial hemorrhage and perinatal stroke are less commonly diagnosed because a lack of easy availability of neuroimaging in LMICs. Although EEG is considered the gold standard for diagnosing seizures, it is not freely available in many neonatal units in LMICs because of its time-consuming nature, expensive equipment, and the requirement for expert interpretation. Although the use of amplitude-integrated electroencephalography (aEEG) is increasing, it is inconsistent, and most units rely on clinical diagnosis of seizures.16,18 A recently published paper by Hunt et al,19 which compared clinical versus aEEG criteria for treatment of seizures, found no statistically significant differences in neurodevelopmental outcomes at 2 years. Thus, a direct extrapolation of the trials conducted in HICs to the infants in LMICs may not be advisable, and there is a need to generate more direct evidence.
With this background, we aimed to evaluate in term moderate to severely asphyxiated inborn neonates the effectiveness of levetiracetam compared with phenobarbitone in clinical seizure control in the first 48 hours of life in this pragmatic, active-control, randomized trial. The primary outcome was clinical seizure control and a seizure-free period of at least 24 hours after the loading dose. In addition, the effectiveness of levetiracetam as an add-on drug and the impact on neurologic status at discharge were also studied as secondary outcomes.
Methods
Study Design and Duration
The study was designed as an open-label, single-center, randomized, active-control, pragmatic trial. It was conducted at a level IIIB NICU of a tertiary care center starting in January 2019, and the recruitment was completed in April 2020.
Participants
Inborn term neonates were included in the study, satisfying the World Health Organization definition of asphyxia (inability to initiate or sustain spontaneous respiration) with clinical seizures in the first 48 hours of life. Infants with antenatally or postnatally diagnosed major congenital malformations and metabolic seizures (hypoglycemia, hypocalcemia, hypomagnesemia, suspected inborn error of metabolism) were excluded.
For inclusion in the study, the following movements lasting longer than 30 seconds were diagnosed as seizures. All seizures were diagnosed and treated by neonatal consultants or fellows in neonatology. Video recording of the seizure was encouraged when feasible and was discussed during review meetings to ensure uniformity in diagnosis:
subtle seizures such as bicycling, pedaling, chewing, eye deviation, etc, with autonomic instability (tachycardia, blood pressure fluctuations, flushing);
tonic seizures;
clonic seizures; and
myoclonic seizures.
Randomization
Randomization was done by using a computer-generated random number table. Allocation concealment was done with sequentially numbered, opaque, and sealed envelopes. When a neonate was eligible to be enrolled, the envelope was opened by a clinician who was not part of the study. After ensuring patency of the airway, breathing, and circulation, infants satisfying the inclusion criteria were randomized to either of the groups mentioned below. Relevant antenatal and maternal details were recorded, and examination findings were documented. The feasibility of masking was assessed but could not be done because of:
the nature of the intervention with infants not responding to the primary anticonvulsant requiring additional treatment, and
logistic and financial constraints.
Intervention
The levetiracetam group infants were loaded with intravenous (IV) levetiracetam (20 mg/kg) diluted to 15 mg/mL in normal saline given slowly over 15 to 20 minutes under cardiorespiratory monitoring. If controlled, maintenance was continued (10 mg/kg/day twice a day). If seizures persisted even after 20 minutes of the loading dose, infants were given IV phenobarbitone (20 mg/kg/loading) followed by maintenance (5 mg/kg/day BD).
The phenobarbitone group was loaded with IV phenobarbitone (20 mg/kg) diluted to 10 mg/mL in normal saline over 20 minutes followed by maintenance of 5 mg/kg/day given in 12 hourly doses. If seizures persisted even after 20 minutes of the loading dose, infants were given injection levetiracetam (20 mg/kg). If seizures continued despite the add-on drug, the infants were treated with phenytoin followed by midazolam infusion according to unit policy. Infants were shifted to the oral formulation of the primary drug after reaching full feeds.
Seizure control was defined as the clinical cessation of abnormal movements and maintenance for at least 24 hours after loading. EEG monitoring could not be done. Modified Sarnat staging for grading hypoxic-ischemic encephalopathy was done in all enrolled infants at 6 hours of age. Complete blood count, renal, and liver function tests were monitored at 72 hours and on day 7. Infants who received therapeutic hypothermia (phase-changing material) and erythropoietin (500 IU/kg on alternate days for 5 doses) as a part of another ongoing trial were also included. These confounders were considered during the final analysis. Neurologic examination at discharge included assessing the level of consciousness, neonatal reflexes, and neurological motor examination using Amel Tison Neurologic Assessment at Term. The duration of anticonvulsant therapy was based on the examination at discharge and follow-up.
Consent and Ethics
Informed consent was obtained from parents on a prestructured proforma after assessing eligibility. The study was approved by the institutional ethics committee and was registered with CTRI (CTRI/2020/05/025416).
Sample Size Calculation
The sample size required for this study based on efficacy was calculated as 76 (38 in each group) with (α) error of 0.05, power of 80%, 1:1 allocation ratio, and assuming a difference in the proportion of outcomes between the groups as 31% (levetiracetam 77% and phenobarbitone 46%, rates of seizure resolution for each drug noted in a recent systematic review).20
Statistical Analysis
Categorical variables were expressed as the number of patients and percentage and compared across the groups by using Pearson's χ-Square test as appropriate for an independence of attributes/Fisher's exact test. Continuous variables were expressed as mean, median, and standard deviation and compared across the groups by using the Mann-Whitney U test. The relative risk and 95% confidence intervals were calculated for primary outcomes. The statistical software SPSS version 20 was used for the analysis. An α level of 5% was taken, (ie, if any P value was <.05) it was considered significant.
Results
A total of 103 infants were considered for eligibility; however, 21 could not satisfy the inclusion criteria (Fig 1). Eighty-two infants were randomly assigned such that 44 were in the levetiracetam group and 38 were in the phenobarbitone group. Baseline demographic and clinical characteristics were comparable in the 2 groups (Table 1).
Baseline and Clinical Characteristics
| Levetiracetam, n = 44 | Phenobarbitone, n = 38 | P | |
|---|---|---|---|
| Gestation, wks, mean (SD) | 38.27 (0.97) | 38.32 (0.99) | >.05 |
| Wt, kg, mean (SD) | 2.60 (0.53) | 2.81 (0.42) | >.05 |
| Sex, n (%) | |||
| Male | 22 (50) | 16 (42.1) | >.05 |
| Female | 22 (50) | 22 (57.9) | >.05 |
| Mode of delivery, n (%) | |||
| Vaginal | 13 (29.5) | 13 (34.2) | >.05 |
| C-section | 27 (61.4) | 22 (57.9) | >.05 |
| Apgar score, median (IQR) | |||
| 1 min | 4 (3−5) | 4 (3−5) | >.05 |
| 5 min | 6 (5−7) | 7 (5−7) | >.05 |
| 10 min | 8 (6.25−8) | 7.5 (6.7−8) | >.05 |
| Modified Sarnat, n (%) | |||
| HIE2 | 38 (86.3) | 32 (84.2) | >.05 |
| HIE3 | 5 (11.3) | 6 (15.8) | >.05 |
| Type of seizure, n (%) | |||
| Subtle | 21 (47.7) | 12 (31.5) | >.05 |
| Clonic | 22 (50) | 20 (52.6) | >.05 |
| Tonic | 9 (20.4) | 6 (15.8) | >.05 |
| Myoclonic | 1 (2.2) | 2 (5.2) | >.05 |
| Age at first seizure, h, mean (SD) | 4.76 (4.52) | 5.03 (6.36) | >.05 |
| Erythropoietin, n (%) | 16 (36.3) | 14 (36.8) | >.05 |
| Therapeutic hypothermia, n (%) | 4 (9.0) | 3 (7.9) | >.05 |
| Mortality, n (%) | 4 (9.0) | 8 (21) | >.05 |
| Levetiracetam, n = 44 | Phenobarbitone, n = 38 | P | |
|---|---|---|---|
| Gestation, wks, mean (SD) | 38.27 (0.97) | 38.32 (0.99) | >.05 |
| Wt, kg, mean (SD) | 2.60 (0.53) | 2.81 (0.42) | >.05 |
| Sex, n (%) | |||
| Male | 22 (50) | 16 (42.1) | >.05 |
| Female | 22 (50) | 22 (57.9) | >.05 |
| Mode of delivery, n (%) | |||
| Vaginal | 13 (29.5) | 13 (34.2) | >.05 |
| C-section | 27 (61.4) | 22 (57.9) | >.05 |
| Apgar score, median (IQR) | |||
| 1 min | 4 (3−5) | 4 (3−5) | >.05 |
| 5 min | 6 (5−7) | 7 (5−7) | >.05 |
| 10 min | 8 (6.25−8) | 7.5 (6.7−8) | >.05 |
| Modified Sarnat, n (%) | |||
| HIE2 | 38 (86.3) | 32 (84.2) | >.05 |
| HIE3 | 5 (11.3) | 6 (15.8) | >.05 |
| Type of seizure, n (%) | |||
| Subtle | 21 (47.7) | 12 (31.5) | >.05 |
| Clonic | 22 (50) | 20 (52.6) | >.05 |
| Tonic | 9 (20.4) | 6 (15.8) | >.05 |
| Myoclonic | 1 (2.2) | 2 (5.2) | >.05 |
| Age at first seizure, h, mean (SD) | 4.76 (4.52) | 5.03 (6.36) | >.05 |
| Erythropoietin, n (%) | 16 (36.3) | 14 (36.8) | >.05 |
| Therapeutic hypothermia, n (%) | 4 (9.0) | 3 (7.9) | >.05 |
| Mortality, n (%) | 4 (9.0) | 8 (21) | >.05 |
HIE, hypoxic ischemic encephalopathy; SD, IQR, interquartile range; standard deviation.
The mean age at enrollment was 4.8 hours. The most common seizure type observed was focal clonic seizures (51.2%). Clinical seizure control with the primary drug and maintenance of the same for 24 hours was observed in 29 infants (65.9%) in the levetiracetam group and 13 infants (34.2%) in the phenobarbitone group (P < .05, relative risk 0.52, 95% confidence interval 0.32–0.84). Of the infants in the phenobarbitone group who did not respond to the loading of the primary drug (phenobarbitone), 57.8% were controlled after levetiracetam (Table 2).
Outcomes
| Levetiracetam (n = 44), n (%) | Phenobarbitone (n = 38), n (%) | Relative Risk | 95% CI | P | |
|---|---|---|---|---|---|
| Seizure control after primary drug | 29 (65.9) | 13 (34.2) | 0.52 | 0.34–0.66 | <.05 |
| Seizures controlled after adding drug of the other group | 14 (31.8) | 22 (57.8) | 0.54 | 0.32–0.91 | <.05 |
| Abnormal neurologic examination at discharge | 6 (13.6) | 11 (28.9) | 0.47 | 0.19–1.15 | >.05 |
| 1. Level of consciousness | 5 (20.4) | 11 (28.9) | — | — | — |
| 2. Neonatal reflexes | 1 (2.2) | 4 (10.5) | — | — | — |
| 3. Neuromotor (ATNAT) | 4 (9) | 11 (28.9) | — | — | — |
| Levetiracetam (n = 44), n (%) | Phenobarbitone (n = 38), n (%) | Relative Risk | 95% CI | P | |
|---|---|---|---|---|---|
| Seizure control after primary drug | 29 (65.9) | 13 (34.2) | 0.52 | 0.34–0.66 | <.05 |
| Seizures controlled after adding drug of the other group | 14 (31.8) | 22 (57.8) | 0.54 | 0.32–0.91 | <.05 |
| Abnormal neurologic examination at discharge | 6 (13.6) | 11 (28.9) | 0.47 | 0.19–1.15 | >.05 |
| 1. Level of consciousness | 5 (20.4) | 11 (28.9) | — | — | — |
| 2. Neonatal reflexes | 1 (2.2) | 4 (10.5) | — | — | — |
| 3. Neuromotor (ATNAT) | 4 (9) | 11 (28.9) | — | — | — |
CI, confidence interval; ATNAT, Amel Tison Neurologic Assessment at Term.
Duration of hospital stay did not differ between the 2 groups (median 8 vs 9 days). Neurologic examination done at discharge was abnormal in 28.9% of infants in the phenobarbitone group and 13.6% of infants in the levetiracetam group (P value .08).
No immediate adverse events were observed in either group. Thrombocytopenia was seen in 11.3% of infants in the levetiracetam group versus 10.5% in the phenobarbitone group. Renal function abnormalities were observed in 22.7% of the infants in the levetiracetam group versus 21% in the phenobarbitone group. In comparison, deranged liver functions were seen in 13.1% in the phenobarbitone group versus 4.5% in the levetiracetam group. None of these differences was found to be statistically significant. Mortality was 9% in the levetiracetam group and 21% in the phenobarbitone group (P >.05) (Table 3).
Haematological and Biochemical Abnormalities
| Laboratory parameters | Levetiracetam (n = 44), n (%) | Phenobarbitone (n = 38), n (%) | P |
|---|---|---|---|
| Thrombocytopenia | 5 (11.3) | 4 (10.5) | >.05 |
| Deranged renal function | 10 (22.7) | 8 (21) | >.05 |
| Deranged liver function | 2 (4.5) | 5 (13.1) | >.05 |
| Laboratory parameters | Levetiracetam (n = 44), n (%) | Phenobarbitone (n = 38), n (%) | P |
|---|---|---|---|
| Thrombocytopenia | 5 (11.3) | 4 (10.5) | >.05 |
| Deranged renal function | 10 (22.7) | 8 (21) | >.05 |
| Deranged liver function | 2 (4.5) | 5 (13.1) | >.05 |
The study was not adequately powered to comment on the side effects.
Of the 16 infants in the levetiracetam group who received erythropoietin, 12 achieved seizure control with the primary drug (75%). Among the 14 infants in the phenobarbitone group who received erythropoietin, seizure cessation with the primary drug was seen in 9 infants (64.2%; P >.05).
Discussion
This study suggests that levetiracetam is more effective when compared with phenobarbitone in seizure control in term asphyxiated infants both as a first-line and add-on drug.
Neonatal seizures are the most typical neurologic emergency and are often associated with poor neurodevelopmental outcomes. Although data on the direct association between neonatal seizures and subsequent morbidities like cerebral palsy, cognitive disabilities, epilepsy, etc is sparse and limited by various confounding factors such as lack of video EEG and the presence of other comorbidities like hypoglycemia, sepsis, ventilation, etc, a direct association between the seizure burden and poor neurologic outcomes has been observed in various studies. A seizure burden of >13 minutes per hour has been observed to increase the odds of an abnormal neurologic outcome by eightfold (odds ratio: 8.00; 95% confidence interval: 2.06–31.07).21,22 However, neonatal seizures are difficult to diagnose, and because of the lack of constant availability of EEG/aEEG and the expertise to interpret it accurately, they pose a particularly significant clinical challenge for neonatologists and neurologists in the LMIC. Clinical diagnosis of seizures has been frequently reported to be inaccurate because clinical seizures are difficult to distinguish from nonseizure behavior. A high proportion of seizures are nonclinical electrographic-only, making confirmation with EEG or aEEG essential. However, this has been challenged by the recent publication by Hunt et al.19 They observed no difference in the neurologic outcomes at 2 years in infants diagnosed clinically or using aEEG.19 Also, most published studies are from high-income countries, making the direct extrapolation to LMICs difficult because the developing countries often face unique problems such as a large number of unbooked cases, inadequate antepartum surveillance, a high incidence of ascending infections, increased incidence of meconium aspiration, and late second stage arrival. Hence there is an urgent need for well-designed studies on accurate yet feasible diagnostic methodology for neonatal seizures and a better understanding of the evolution and timing of insult and, thus, the response to treatment in the LMICs.
Although levetiracetam is often used as a second-line drug in newborns failing to respond to phenobarbitone, not enough data on its use as a first-line drug is available in the literature. In a randomized trial by Gowda et al13 of 100 newborns, the authors suggested levetiracetam to be superior to phenobarbitone in neonatal seizures. Although not specific to asphyxia, the authors of the study by Gowda et al13 suggest that levetiracetam may have a role as a primary drug in neonatal seizures. In a systematic review on the efficacy of levetiracetam by McHugh et al,20 the authors found it to be at least as effective as phenobarbitone. However, the study population included both term and preterm infants, and seizure control was defined on the basis of EEG characteristics. In a retrospective review of 78 term newborns with hypoxic encephalopathy by Rao et al,11 the authors suggested levetiracetam to be a viable alternative to phenobarbitone, with a shorter time to seizure freedom, based on video EEG records. In a retrospective analysis of 22 term newborns by Khan et al,23 86% of infants demonstrated a response to levetiracetam; however, 72% had received levetiracetam as a second-line agent. These studies reveal the possible role of levetiracetam as an effective alternative to phenobarbitone, consistent with the current study.
A randomized pilot trial with 60 asphyxiated infants by Perveen et al24 revealed seizure control in only 23.3% of neonates assigned to receive levetiracetam compared with 86.7% of neonates with phenobarbitone. In a large, multicenter, randomized, controlled trial by Sharpe et al,14 the NEOLEV2 trial authors found 80% seizure control in the phenobarbitone group compared with only 28% in the levetiracetam group. Seizure control in this trial was based on continuous EEG monitoring, which could not be done in our study. Also, as discussed in the background section, only ∼50% of the infants were HIE infants, and all received therapeutic hypothermia. The results are in stark contrast to that of the current study. Still, the authors believe that a direct comparison cannot be made. More research on the timing of insult and response to treatment needs to be done in LMICs because the infants may respond differently, as observed in the HELIX trial.17 Abend et al25 found a 35% response to levetiracetam in their retrospective cohort study. However, 61% of the infants had received levetiracetam as a second-line drug. These contrasting results suggest the need for a large multicenter trial to provide concrete answers.
The optimal dosage and interval of levetiracetam in newborns have not been established. Pharmacokinetic data from adults reveals that levetiracetam exhibits high bioavailability (>95%), quickly reaches the peak and steady-state concentrations in 1.3 hours, and displays linear time-dependent kinetics. Type-B esterases metabolize levetiracetam in whole blood to inactive metabolites, and almost 66% is excreted by the renal route. Pharmacokinetic data from the neonatal population is limited, but various studies reveal that there may be a decrease in esterase enzyme activity in asphyxiated neonates. Also, the renal function and drug excretion in asphyxiated neonates are decreased. Thus, the loading and maintenance dose used in the current study was the least effective dose as identified from past studies as the provision for therapeutic drug monitoring was not available.26–29 Sharpe et al30 favored 8 hourly doses whereas Merhar27 supported 12 hourly intervals like used in the current study. Results from a dose-finding trial (LEVNEONAT-1) from France are awaited.31 Although no immediate adverse effects were observed in either of the groups and hematologic and biochemical parameters did not differ significantly, conclusions regarding the side-effect profile cannot be made as the study was not powered for this outcome.
The strengths of this study include that, firstly, it is one of the few randomized trials using levetiracetam as a first-line drug in asphyxiated infants. Secondly, because most of the units in LMICs, which have a significant proportion of asphyxiated infants, rely on clinical diagnosis of seizures, and continuous aEEG monitoring is not widely available, the results of this pragmatic trial can be applied to a large population.
The limitations of our study were that we did not perform continuous EEG monitoring to diagnose seizures and the response to treatment. Clinical diagnosis of seizures in sick infants is complex, and various studies have revealed poor interobserver agreement and inconsistency in differentiating nonepileptic movements from seizures;32,33 as much as two-thirds of the clinical manifestations have been reported to be misinterpreted or missed by even experienced neonatal staff.34 However, as stated above, in most neonatal units with limited resources, clinical control of seizures is usually the only guide to treatment. In addition, the randomization process lessens the bias created by the potential for misdiagnosis. Lack of masking, no long-term follow-up, and the inability to perform therapeutic drug monitoring were other limitations of this study.
Conclusion
Levetiracetam can be used with efficacy as a first- and second-line drug in asphyxiated term infants. A larger study on pharmacokinetics and optimal regimen is required.
Dr Sukena conceptualized and designed the study and drafted the initial manuscript; Drs Deshmukh, Joshi, and Londhe conducted the data collection and initial analyses and reviewed and revised the manuscript; and all authors approved the final manuscript as submitted and agree to be accountable for all aspects of the work.
FUNDING: No external funding.
CONFLICT OF INTEREST DISCLOSURES: The authors have indicated they have no potential conflicts of interest relevant to this article to disclose.
CLINICAL TRIALS IDENTIFICATION: This trial has been registered with the Clinical Trials Registry of India (http://ctri.nic.in/Clinicaltrials/login.php.) (identifier CTRI/2020/05/025416).
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