Significant Food Effect Research Articles

Effect of particle size reduction on dissolution and oral absorption of a poorly water-soluble drug, cilostazol, in beagle dogs

The purpose of the present study was to investigate the effects of particle size on the dissolution and oral absorption of cilostazol. Three types of suspensions having different particle size distributions were prepared of the hammer-milled, the jet-milled cilostazol crystals and the NanoCrystal® spray-dried powder of cilostazol. In vitro dissolution rate of cilostazol was significantly increased by reducing the particle size. The dissolution curves of the cilostazol suspensions were in good agreement with the simulation based on the Noyes–Whitney equation. The bioavailability of cilostazol after oral administration to dogs was increased with reducing the particle size. While positive food effect on the absorption was observed for the suspensions made of the hammer-milled and the jet-milled crystals, no significant food effect was found for the suspension made of the NanoCrystal® cilostazol spray-dried powder. These results could be qualitatively predicted from the in vitro dissolution data using the bio-relevant media, FaSSIF and FeSSIF. In conclusion, the NanoCrystal® technology is found to be efficient to improve the oral bioavailability of cilostazol and to avoid the food effect on the absorption.

Predicting Pharmacokinetic Food Effects Using Biorelevant Solubility Media and Physiologically Based Modelling

Food-induced changes in gastric emptying time, gastric pH and/or intestinal fluid composition may have an impact on the pharmacokinetics of drugs. The aim of this work was to use mathematical models describing physiology in fed and fasted states together with biorelevant solubility and degradation data to simulate food effects for six compounds from recent Roche projects. The solubility of each compound was measured in different biorelevant media: simulated human gastric fluid for the fasted and fed state, simulated human intestinal fluid for the fasted, fed and high-fat state, and simulated human colonic fluid for the upper and the lower colon. A physiologically based absorption model was developed in GastroPlustrade mark for each compound using permeability, solubility, metabolism and distribution data. By incorporating the appropriate physiological parameters and solubility data into the model, the oral pharmacokinetics of each drug was simulated under fasted, fed and/or high-fat conditions. Predicted and observed plasma concentration-time profiles and food effects were compared for a range of doses to assess the accuracy of the simulations. The models were able to distinguish between minor and significant food effects. The simulation captured well the magnitude of the food effects and for the six compounds correctly predicted the observed plasma exposure in fasted, fed and high-fat conditions. Biorelevant solubility tests can be used together with physiologically based absorption models to predict clinical food effects caused by solubility and/or dissolution rate limitations.

Clinical Pharmacology and Pharmacokinetics of Once‐Daily Hydromorphone Hydrochloride Extended‐Release Capsules

Hydromorphone hydrochloride extended release (HHER) is a multiparticulate melt-extrusion pellet capsule formulation administered q24h. Study 1 investigated the bioavailability of 24-mg HHER fed, as well as 24-mg and 12-mg HHER and 8-mg hydromorphone hydrochloride immediate-release (HHIR) tablets fasting. No clinically significant food effect was observed on hydromorphone C(max) or AUC for the 24-mg HHER, and dose proportionality (AUC) was demonstrated between 12- and 24-mg HHER. Study 2 demonstrated dose strength proportionality for 3 x 12-mg HHER versus 1 x 32-mg HHER. Study 3 evaluated 12-mg HHER q24h versus 3-mg HHIR q6h at steady state. HHER produced relatively constant steady-state concentrations over 24 hours. HHER and HHIR were equivalent for AUC(ss). C(ssmax) was 26% lower for HHER than HHIR, C(ssmin) was 43% higher for HHER, and peak-to-trough fluctuation was 126% for HHER versus 328% for HHIR, which are ideal attributes of a once-daily oral extended-release dosage form. HHER administration resulted in fewer adverse events than HHIR in study 3.

The role of biopharmaceutics in the development of a clinical nanoparticle formulation of MK-0869: a Beagle dog model predicts improved bioavailability and diminished food effect on absorption in human

MK-0869 (aprepitant), a potent substance P antagonist, is the active ingredient of EMEND ® which has recently been approved by the FDA for the prevention of chemotherapy-induced nausea and vomiting. Early clinical tablet formulations of MK-0869 showed significant food effects on absorption, suggesting that formulation could have a significant role in improving bioavailability. A Beagle dog model was developed in an effort to guide novel formulation development. Using the suspension of the micronized bulk drug used for the tablet formulations, the food effect on absorption was confirmed in the dog at a similar magnitude to that observed in humans. Further dog studies demonstrated a clear correlation between particle size and in vivo exposures, with the nanoparticle (NanoCrystal ®) colloidal dispersion formulation providing the highest exposure, suggesting dissolution-limited absorption. The NanoCrystal ® dispersion also eliminated the food effect on oral absorption in the dog at a dose of 2 mg/kg. Regional absorption studies using triport dogs indicated that the absorption of MK-0869 was limited to the upper gastrointestinal tract. These results provided strong evidence that the large increase in surface areas of the drug nanoparticles could overcome the narrow absorption window and lead to rapid in vivo dissolution, fast absorption, and increased bioavailability. In addition, the dog model was used for optimizing formulation processes in which the nanoparticles were incorporated into solid dosage forms, and for selecting excipients to effectively re-disperse the nanoparticles from the dosage units. The human pharmacokinetic data using the nanoparticle formulation showed excellent correlations with those generated in the dog.

Phase I study of the novel, oral angiogenesis inhibitor PTK787/ZK 222584 (PTK/ZK): Evaluating the pharmacokinetic effect of a high-fat meal in patients with hormone-refractory prostate cancer (HRPC)

4689 Background: PTK/ZK is a novel, oral angiogenesis inhibitor that potently inhibits all known VEGF receptors, important mediators of tumor growth and metastasis. This phase I study in patients (pts) with HRPC assessed the effect of food on the pharmacokinetics (PK) of PTK/ZK and evaluated safety and preliminary efficacy (defined as changes in serum prostate-specific antigen [PSA] levels). Methods: Pts with HRPC received 1,000 mg/day PTK/ZK and were randomized to fed or fasted conditions on days 15, 18, 22, and 25. Blood was collected over 24 hr to assess the PK of PTK/ZK and PSA levels. Results: Of 23 pts treated, 1 pt discontinued due to disease-related adverse event (AE), and 3 due to drug-related AEs. PK data from 19 evaluable pts showed that administration of PTK/ZK with food resulted in a delay in absorption (Tmax increased from 2.0 to 4.0 hr; P < .001), decreased Cmax by 12% (fed:fasted ratio of 0.88; 90% CI = 0.72, 1.08), and increased AUC by 27% (fed:fasted ratio of 1.27; 90% CI = 1.07, 1.52). PK variability was moderate with intrapatient CV% of 21% - 25% and interpatient CV% of 42% for Cmax and AUC; variability was slightly higher under fed conditions. Commonly reported AEs were mostly grades 1/2: nausea (70%), dizziness (52%), headache (52%), hypertension (39%), vomiting (39%), arthralgia (35%), fatigue (30%), constipation (26%), anorexia (17%), back pain (17%), bone pain (13%), and cough (13%). Grade 3 AEs (> 5%) were hypertension (17%) and syncope (9%). The incidence of AEs was similar on fasting and fed days. Overall median time to PSA progression (TTP) was 2 mo. One pt had a 68% reduction from baseline in serum PSA level and TTP of 12 mo; 2 other pts demonstrated > 40% reductions in PSA and TTP of 4 and 5 mo, respectively. Conclusions: The small food effect observed in this study was not associated with higher frequency or severity of AEs on fed vs fasted days, suggesting that the small but statistically significant food effect is not clinically significant, and that PTK/ZK may be taken with or without food. PTK/ZK also exhibited clinical activity in pts with HRPC. Author Disclosure Employment or Leadership Consultant or Advisory Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Novartis Pharmaceuticals; Schering AG

Phase I study of the novel, oral angiogenesis inhibitor PTK787/ZK 222584 (PTK/ZK): Evaluating the pharmacokinetic effect of a high-fat meal in patients with hormone-refractory prostate cancer (HRPC)

4689 Background: PTK/ZK is a novel, oral angiogenesis inhibitor that potently inhibits all known VEGF receptors, important mediators of tumor growth and metastasis. This phase I study in patients (pts) with HRPC assessed the effect of food on the pharmacokinetics (PK) of PTK/ZK and evaluated safety and preliminary efficacy (defined as changes in serum prostate-specific antigen [PSA] levels). Methods: Pts with HRPC received 1,000 mg/day PTK/ZK and were randomized to fed or fasted conditions on days 15, 18, 22, and 25. Blood was collected over 24 hr to assess the PK of PTK/ZK and PSA levels. Results: Of 23 pts treated, 1 pt discontinued due to disease-related adverse event (AE), and 3 due to drug-related AEs. PK data from 19 evaluable pts showed that administration of PTK/ZK with food resulted in a delay in absorption (Tmax increased from 2.0 to 4.0 hr; P < .001), decreased Cmax by 12% (fed:fasted ratio of 0.88; 90% CI = 0.72, 1.08), and increased AUC by 27% (fed:fasted ratio of 1.27; 90% CI = 1.07, 1.52). PK variability was moderate with intrapatient CV% of 21% - 25% and interpatient CV% of 42% for Cmax and AUC; variability was slightly higher under fed conditions. Commonly reported AEs were mostly grades 1/2: nausea (70%), dizziness (52%), headache (52%), hypertension (39%), vomiting (39%), arthralgia (35%), fatigue (30%), constipation (26%), anorexia (17%), back pain (17%), bone pain (13%), and cough (13%). Grade 3 AEs (> 5%) were hypertension (17%) and syncope (9%). The incidence of AEs was similar on fasting and fed days. Overall median time to PSA progression (TTP) was 2 mo. One pt had a 68% reduction from baseline in serum PSA level and TTP of 12 mo; 2 other pts demonstrated > 40% reductions in PSA and TTP of 4 and 5 mo, respectively. Conclusions: The small food effect observed in this study was not associated with higher frequency or severity of AEs on fed vs fasted days, suggesting that the small but statistically significant food effect is not clinically significant, and that PTK/ZK may be taken with or without food. PTK/ZK also exhibited clinical activity in pts with HRPC. Author Disclosure Employment or Leadership Consultant or Advisory Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Novartis Pharmaceuticals; Schering AG

Effects of Growth History and Exogenous Thyroxine on Size and Age at Metamorphosis in the ToadBufo americanus

By using food rations and thyroxine supplements, I manipulated the growth and differentiation of tadpoles of the toad Bufo americanus to test the hypothesis that the plasticity in metamorphic timing can be lost. A significant food effect indicated that tadpoles that grew rapidly during the middle period of the experiment metamorphosed earlier than slow-growing tadpoles. The changes in growth induced early and late in this experiment did not influence metamorphic timing. There was a significant thyroxine effect: all tadpoles treated with thyroxine metamorphosed early. All thyroxine-treated tadpoles metamorphosed at the same time, indicating that differentiation at the time of thyroxine supplementation was independent of growth rate. A food-by-thyroxine interaction provided evidence that the growth rate/differentiation antagonism may have been active at least during the middle of the experiment. This suggests that the growth rate/differentiation antagonism is decoupled or overridden during later stages of larval development. This result implies limits to metamorphic plasticity and is consistent with a fixed-rate model of amphibian metamorphosis.

Tests of two theories of food intake using growing pigs 1. The effect of ambient temperature on the intake of foods of differing bulk content

AbstractAn experiment was carried out on pigs to provide a test of two current conceptual frameworks available for the understanding and prediction of food intake. Framework 1 assumes that food intake will be that which allows potential (genetic) performance to be achieved. If this is not achieved then it is because intake is being constrained. Framework 2 sees food intake as being a consequence of a process of optimization such that biological efficiency (the ratio of net energy ingested to oxygen consumed) is maximized. Both frameworks predict that a reduction in temperature will increase the intake of a high quality food. For a food of low quality framework 2 predicts that intake will also be increased when temperature is decreased while framework 1 predicts that it will not. This difference between the predictions of the two frameworks allows them to be tested by means of an experiment in which foods of different quality were given to animals at different environmental temperatures.Forty pigs were randomly allocated to a control (C) food based on micronized wheat with 13·1 MJ digestible energy (DE) and 232 g crude protein (CP) per kg fresh food, or one of two high bulk foods. The high bulk foods contained either 650 g/kg of unmolassed sugar-beet pulp (SBP) or 650 g/kg of wheat bran (WB). Half the pigs were maintained at a thermoneutral temperature of 22ºC for 14 days followed by a cold temperature of 12ºC for 14 days. The other half were maintained at 12ºC for a period of 14 days followed by a temperature of 22ºC for 14 days. Food intake was recorded daily and live weight twice weekly.There was a highly significant food ✕ temperature interaction ( P &lt; 0·001) for food intake. A reduction in temperature resulted in an increase in food intake on C and WB but had no effect on the intake of SBP. There was a highly significant effect of both temperature and food on intake ( P &lt; 0·001). A reduction in temperature resulted in a significant increase in food intake, intake on WB was higher than that of either C or SBP. There was no overall effect of temperature on live-weight gain although a reduction in temperature resulted in a non-significant increase in the gain of C and reduction in the gain of WB and SBP. There was a highly significant effect of food ( P &lt; 0·001) on live-weight gain, as gain on C was higher than that on either WB or SBP.The results of the experiment were in agreement with the predictions set forward by the first framework that growing pigs are eating to achieve maximum performance subject to constraints.

Effect of food on the pharmacokinetics of YH439 and its metabolites in rats

The pharmacokinetics of YH439 and its metabolites were investigated after oral administration of YH439 to rats to investigate the food effect. After oral administration of YH439, its metabolites, M4 and M5 were detected in plasma. YH439 was not detected in the plasma for both fasted and fed rats for all doses studied. The pharmacokinetic parameters of the metabolites were not affected by food at all doses studied. The results of this study indicated that there are no significant food effects on the pharmacokinetics of YH439 and its metabolites in rats.

Examination of two sustained release nifedipine preparations in humans and in pigs

In the present study, the ability of the pig to discriminate the in-vivo release characteristics of two 60 mg sustained release nifedipine formulations, an experimental formulation (Faulding) and Procardia XL (Pfizer), under both fasting and fed conditions was assessed. These forms had previously been evaluated in humans, where an alteration in the release profile of the experimental formulation was noted following administration with food. 12 Large White female pigs (mean weight 38 kg) were divided into two groups and each group was orally administered one of the two products under both fasting and fed conditions. The mean area under the plasma concentration-time curve was not significantly different between the formulations under both conditions. The mean maximum observed plasma concentration ( C max) was significantly higher for the experimental formulation when compared against Procardia XL under both fasting ( P<0.05) and fed ( P<0.05) conditions. Peak concentrations were achieved at approximately 6 h for the experimental formulation and 12 h for Procardia XL. The time for which the plasma concentration exceeded 75% of C max was approximately 2.5-fold greater for Procardia XL than for the experimental formulation. There were no significant food effects on the relative bioavailability nor release profiles of the two formulations. The results obtained suggest that the pig may be a useful model in differentiating the release profiles of nifedipine formulations for the fed state in humans as results were similar to the human-fed study, but dissimilar to the human-fasted study.

Single-dose pharmacokinetics and effect of food on the bioavailability of topiramate, a novel antiepileptic drug.

Topiramate, a new antiepileptic drug effective in controlling partial-onset seizures, was administered to humans for the first time as single oral doses of 100 mg, 200 mg, 400 mg, 800 mg, and 1,200 mg in a phase I safety and pharmacokinetic study. Model-independent pharmacokinetic data analysis was performed on plasma concentration and renal excretion data for topiramate. Maximum plasma concentrations (Cmax) were observed between 1.4 and 4.3 hours after administration. Mean values for plasma Cmax and area under the concentration-time curve (AUC) increased linearly with dose; however, a greater-than-proportional increase in both parameters was observed, probably due to saturable binding of the drug to erythrocytes. Mean oral clearance (Cl/F) was 22.5 to 36.1 mL/min and mean volume of distribution (Vd/F) was 38.5 to 58.0 L. Approximately 50% of the dose was excreted renally and cumulative urinary excretion increased linearly and proportionally over the 200 mg to 1,200 mg dose range. Elimination half-life (t1/2) values calculated from plasma (21.5 hrs) and urinary data (18.5 hrs) were consistent and independent of dose. Intersubject variability was low for all parameters. Renal clearance was 13.9 mL/min, suggesting that renal tubular reabsorption may be prominently involved in the renal handling of topiramate. The elimination profile of topiramate indicated that longer sampling times are necessary in future studies to more accurately determine the t1/2. Food effect studies indicated a slight reduction in the rate (approximately 10% decrease in mean Cmax and mean tmax approximately 2 hours later) but not the extent of absorption when topiramate was given with food. Topiramate demonstrates a number of favorable pharmacokinetic features, including linear and predictable dose-concentration relationships, excretion mainly as unchanged drug by the kidney, a dose-independent t1/2, low intersubject variability in pharmacokinetic parameters, and lack of clinically significant effect of food on bioavailability.

Differential Effects of Food on the Bioavailability of Controlled-Release Oxycodone Tablets and Immediate-Release Oxycodone Solution

AbstractThe effects of a high-fat meal on the bioavailability of oxycodone hydrochloride, administered as a recently developed 40mg controlled-release (CR) tablet or a 20mg immediate-release (IR) solution, were evaluated in a randomized crossover study in 22 normal male and female subjects. Serial blood samples were collected for 36h after dosing and analyzed for oxycodone by a validated method using gas chromatography/mass spectrometry. There was no significant food effect with CR oxycodone as judged by 90% confidence interval (CI) analysis of AUC0−∞and Cmax values under fed and fasted conditions. For the IR solution, both oxycodone bioavailability and peak plasma oxycodone concentration were significantly altered by consumption of the high-fat meal, with the mean value for AUC0−∞ increasing to 120% (CI=109– 132%) and the mean value for Cmax decreasing to 82% (CI=47–91%) of values observed in the fasted condition. Adverse events reported for both formulations were mostly mild to moderate in severity and typical of those observed with opioids.

Interactions of Intraspecific, Interspecific, and Apparent Competition with Host‐Pathogen Population Dynamics

I investigated the interactions of intra— and interspecific competition with parasitism for populations of two terrestrial isopods, Porcellio scaber and Porcellio laevis, infected with a lethal virus. In field experiments, I varied densities of one or both isopod species in enclosures in which food and virus presence were also manipulated. I estimated the effects of intra— and interspecific competition, additional food, and virus infection on both the survival of P. scaber and the prevalence of the virus. In uninfected populations, intraspecific and interspecific competition negatively affected isopod survival, although food resources had no effect. In infected treatments, interspecific competition produced higher levels of virus prevalence than did intraspecific competition. Virus infection and reduced food interacted to produce higher overall mortality in interspecific competition treatments than in intraspecific competition treatments. The lack of significant effect of food on competition suggests that interference interactions rather than resource competition predominated. This mechanism is supported by a laboratory study in which total food availability was controlled. These results indicate that competition and parasitism interacted to produce the observed mortality patterns, and that ignoring mortality due to the virus would produce apparent interspecific competition. The data suggest that the impact of P. laevis on P. scaber involves both direct and indirect effects.

Experimental studies of food and suspended sediment effects on growth and reproduction of six planktonic cladocerans

Life-long somatic growth and egg production responses of Daphnia barbata, Daphnia gibba, Daphnia laevis, Daphnia pulex, Moina micrura and Diaphanosoma excisum were examined in relation to different food and suspended sediment levels, in factorial experiments at 20°C. Food treatments involved additions of 0, 100, 500 and 2500 μg C l−1 of Selenastrum to 20 μm filtered water, generally from source lakes. These food levels were tested at two suspended sediment levels in all species, viz. (i) natural source-lake nephelometric turbidities of 7–65 nephelometric turbidity units (NTU) (˜10–70 mg l−1 TSS) and (ii) ˜3- to 4-fold enrichment of natural levels (8-fold in D.excisum). A third sediment-free treatment was tested in all species of Daphnia other than D.gibba. Growth in body length and reproductive output were assessed daily for individual animals. Main and interactive effects of food and sediment on growth were assessed at selected ages from day 3 through subsequent life using analysis of variance (ANOVA). Strong and highly significant positive food effects were apparent at all ages in all species examined, with the curious exception of D.excisum. The onset of maturity and fecundity were also positively related to food level. Sediment effects on growth, age of maturity and fecundity were variable, but tended to be much weaker than food effects. Both stimulatory (positive, especially at low food levels) and inhibitory (negative) effects of sediment on growth were apparent, both between and within species. Performance in sediment-free water was very poor, except in D.pulex. Food-sediment interaction effects were variable. Generally, turbidwater species were influenced less adversely by sediment than clear-water species, indicating the existence of environmentally appropriate adaptive responses. Overall, the findings indicate that light limitation of algal resources by suspended sediments, rather than the condition of high turbidity per se, is responsible for the apparently negative impact of suspended sediments frequently observed on natural populations of cladoceran zooplankters.

Pharmacokinetics of Intravenous Cefetamet and Oral Cefetamet Pivoxil in Human Subjects

Cefetamet pivoxil (pivoxyl) belongs to the class of orally absorbed prodrug esters that are hydrolysed to the active compound (Cefetamet) on first pass through the gut wall, the liver or both. Intravenously administered cefetamet is eliminated predominantly unchanged in the urine by glomerular filtration. Systemic and renal clearance values for cefetamet were 8.16 and 7.14 L/h (136 and 119 ml/min), respectively. Plasma protein binding is 22% and steady-state volume of distribution (0.29 L/kg) corresponds roughly to the extracellular water space. Cefetamet pivoxil exhibits a significant positive food effect (40 vs 50%) after oral administration. Hence, it is recommended that cefetamet pivoxil is taken with meals. The food effect is not related to changes in gastric pH, since a mixture of aluminium and magnesium hydroxide (Maalox®) or ranitidine did not affect the bioavailability. The predominant renal elimination of cefetamet and the lack of effect of age and disease on cefetamet pivoxil absorption make dosage adjustment in relation to renal dysfunction simple and reliable. The recommended dosage regimen for susceptible bacterial strains in adults with normal renal function is cefetamet pivoxil 500mg twice daily. The same dosage schedule can be used in children, with dose adjustments made according to body surface area.

Pharmacokinetics of oral cefetamet pivoxil (Ro 15-8075) and intravenous cefetamet (Ro 15-8074) in humans: a review.

Cefetamet pivoxil belongs to the class of orally absorbed pro-drug esters which are hydrolyzed to the active compound (cefetamet) on their first pass through the gut wall and/or the liver. The intravenously administered cefetamet is eliminated predominantly unchanged in the urine by glomerular filtration. Systemic and renal clearance values for cefetamet were 140 and 130 ml/min, respectively. The plasma protein binding is 22%, whereby the only binding protein is albumin. The steady state volume of distribution (0.29 l/kg) corresponds roughly to the extracellular water space which is consistent with other low protein-bound cephalosporins. In general, after intravenous doses, cefetamet follows the kinetic behaviour of a cephalosporin with low protein binding, limited non-renal clearance, and renal clearance that is predominantly due to glomerular filtration, e.g. ceftizoxime, ceftazidime. After oral administration, cefetamet pivoxil shows a significant food effect (F = 41% vs 51%). Hence, cefetamet pivoxil is recommended to be taken after food. The food effect, however, is not of such a magnitude that it will be of clinical consequence when this recommendation is not followed. The food effect is not related to a change in gastric pH because antacids and ranitidine do not affect the absorption of cefetamet pivoxil, although in approximately 20% of the subjects absorption of the drug is delayed. The elimination of cefetamet is directly proportional to renal function. In patients with varying degrees of renal insufficiencies, dosage should be decreased accordingly. Age has no effect on the bioavailability of cefetamet pivoxil. However, the clearance of cefetamet is higher in children and lower in the elderly.

Bioavailability of 5-[4-(1-methylcyclohexylmethoxy)benzyl]-thiazolidine-2,4-dione ( ADD-3878) in beagle dogs

The fundamental pharmacokinetic properties of ADD-3878 were evaluated and the bioavailability of the drug after oral administration was determined in beagle dogs. A pharmacokinetic analysis after intravenous injection of the drug revealed biphasic elimination of the plasma ADD-3878 concentration following a biexponential model with a t 1 2 ,α of 0.27 h and a t 1 2 ,β of 17.11 h. The gastrointestinal absorption of ADD-3878 in solution was significantly faster than those in suspensions. The particle size of ADD-3878 crystals affected both the extent and rate of bioavailability. Furthermore, a significant effect of food on the bioavailability of the drug was observed; the absorption in tablets after food ingestion was approximately double of that in the fasting state. The maximum plasma levels and the areas under the curve at various doses of tablets were proportional to the doses. In a multiple-dose study, there was no unusual accumulation of plasma ADD-3878 concentration.