Intraindividual variability of paracetamol absorption kinetics after a semi-solid meal in healthy volunteers

The time to peak blood bicarbonate (HCO3-), pH, and the strong ion difference (SID) following sodium bicarbonate (NaHCO3) ingestion in highly trained adolescent swimmers

The timing of sodium bicarbonate (NaHCO₃) supplementation has been suggested to be most optimal when coincided with a personal time that bicarbonate (HCO₃^–) or pH peaks in the blood following ingestion. However, the ergogenic mechanisms supporting this ingestion strategy are strongly contested. It is therefore plausible that NaHCO₃ may be ergogenic by causing beneficial shifts in the strong ion difference (SID), though the time course of this blood acid base balance variable is yet to be investigated. Twelve highly trained, adolescent swimmers (age: 15.9 ± 1.0 years, body mass: 65.3 ± 9.6 kg) consumed their typical pre-competition nutrition 1–3 hours before ingesting 0.3 g∙kg BM^-1 NaHCO₃ in gelatine capsules. Capillary blood samples were then taken during seated rest on nine occasions (0, 60, 75, 90, 105, 120, 135, 150, 165 min post-ingestion) to identify the time course changes in HCO₃^–, pH, and the SID. No significant differences were found in the time to peak of each blood measure (HCO₃^–: 130 ± 35 min, pH: 120 ± 38 min, SID: 98 ± 37 min; p = 0.08); however, a large effect size was calculated between time to peak HCO₃^– and the SID (g = 0.88). Considering that a difference between time to peak blood HCO₃^– and the SID was identified in adolescents, future research should compare the ergogenic effects of these two individualized NaHCO₃ ingestion strategies compared to a traditional, standardized approach.

The Reproducibility of Blood Acid Base Responses in Male Collegiate Athletes Following Individualised Doses of Sodium Bicarbonate: A Randomised Controlled Crossover Study

BACKGROUND

Current evidence suggests sodium bicarbonate (NaHCO₃) should be ingested based upon the individualised alkalotic peak of either blood pH or bicarbonate (HCO₃^-) because of large inter-individual variations (10-180 min). If such a strategy is to be practical, the blood analyte response needs to be reproducible.

OBJECTIVE

This study aimed to evaluate the degree of reproducibility of both time to peak (TTP) and absolute change in blood pH, HCO₃^- and sodium (Na⁺) following acute NaHCO₃ ingestion.

METHODS

Male participants (n = 15) with backgrounds in rugby, football or sprinting completed six randomised treatments entailing ingestion of two doses of 0.2 g·kg^-1 body mass (BM) NaHCO₃ (SBC2a and b), two doses of 0.3 g·kg^-1 BM NaHCO₃ (SBC3a and b) or two control treatments (CON1a and b) on separate days. Blood analysis included pH, HCO₃^- and Na⁺ prior to and at regular time points following NaHCO₃ ingestion over a 3-h period.

RESULTS

HCO₃^- displayed greater reproducibility than pH in intraclass correlation coefficient (ICC) analysis for both TTP (HCO₃^- SBC2 r = 0.77, P = 0.003; SBC3 r = 0.94, P < 0.001; pH SBC2 r = 0.62, P = 0.044; SBC3 r = 0.71, P = 0.016) and absolute change (HCO₃^- SBC2 r = 0.89, P < 0.001; SBC3 r = 0.76, P = 0.008; pH SBC2 r = 0.84, P = 0.001; SBC3 r = 0.62, P = 0.041).

CONCLUSION

Our results indicate that both TTP and absolute change in HCO₃^- is more reliable than pH. As such, these data provide support for an individualised NaHCO₃ ingestion strategy to consistently elicit peak alkalosis before exercise. Future work should utilise an individualised NaHCO₃ ingestion strategy based on HCO₃^- responses and evaluate effects on exercise performance.

Human digestion--a processing perspective

The human digestive system is reviewed in the context of a process with four major unit operations: oral processing to reduce particle size and produce a bolus; gastric processing to initiate chemical and enzymatic breakdown; small intestinal processing to break down macromolecules and absorb nutrients; and fermentation and water removal in the colon. Topics are highlighted about which we need to know more, including effects of aging and dentition on particle size in the bolus, effects of different patterns of food and beverage intake on nutrition, changes in saliva production and composition, mechanical effects of gastric processing, distribution of pH in the stomach, physicochemical and enzymatic effects on nutrient availability and uptake in the small intestine, and the composition, effects of and changes in the microbiota of the colon. Current topics of interest including food synergy, gut-brain interactions, nutritional phenotype and digestion in the elderly are considered. Finally, opportunities for food design based on an understanding of digestive processing are discussed.

Whey protein delays gastric emptying and suppresses plasma fatty acids and their metabolites compared to casein, gluten, and fish protein

Whey protein has been demonstrated to improve fasting lipid and insulin response in overweight and obese individuals. To establish new hypotheses for this effect and to investigate the impact of stomach emptying, we compared plasma profiles after intake of whey isolate (WI), casein, gluten (GLU), and cod (COD). Obese, nondiabetic subjects were included in the randomized, blinded, crossover meal study. Subjects ingested a high fat meal containing one of the four protein sources. Plasma samples were collected at five time points and metabolites analyzed using LC-Q-TOF-MS. In contrast to previous studies, the WI meal caused a decreased rate of gastric emptying compared to the other test meals. The WI meal also caused elevated levels of a number of amino acids, possibly stimulating insulin release leading to reduced plasma glucose. The WI meal also caused decreased levels of a number of fatty acids, while the GLU meal caused elevated levels of a number of unidentified hydroxy fatty acids and dicarboxylic fatty acids. Also reported are a number of markers of fish intake unique to the COD meal.

Acetaminophen Overdose with Altered Acetaminophen Pharmacokinetics and Hepatotoxicity Associated with Premature Cessation of Intravenous N-Acetylcysteine Therapy

Objective

To report a case of erratic absorption, double peak serum concentrations, and hepatotoxicity following premature cessation of intravenous N-acetylcysteine (NAC) treatment in the setting of a massive acetaminophen overdose.

Case Summary:

A 78-year-old man reportedly ingested approximately 96 immediate-release acetaminophen 500-mg tablets (48 g) over a one-hour period in an apparent suicide attempt. The acetaminophen concentration at 2.25 hours was 264 μg/mL. Intravenous NAC was initiated 5 hours postingestion. At 6.25 hours postingestion, the acetaminophen concentration was 281 μg/mL. Following administration of intravenous NAC for 21 hours, therapy was discontinued despite a residual acetaminophen concentration of 116 μg/mL. The patient experienced hepatotoxicity, coagulopathy, and renal injury. Pharmacokinetic analysis revealed significantly prolonged acetaminophen absorption and a second peak acetaminophen concentration of 228 μg/mL approximately 48 hours post ingestion. Direct in-hospital monitoring of the patient made a second ingestion unlikely.

Discussion:

Acetaminophen overdose is usually effectively managed with NAC. Patients with massive ingestions may have altered absorption kinetics due to acetaminophen's solubility being exceeded, physiologically or chemically altered gastrointestinal emptying or motility, or other factors. These patients may benefit from gastrointestinal decontamination and prolonged NAC therapy.

Conclusions:

In patients with massive acetaminophen ingestion, erratic absorption may occur, and toxic serum concentrations may persist beyond a standard 21–hour course of intravenous NAC therapy. Acetaminophen concentrations and aminotransferase levels should be evaluated at the completion of the intravenous NAC infusion to ensure complete elimination of acetaminophen and absence of hepatotoxicity and to exclude the need lor prolonged treatment.

Characteristics of Acetaminophen Absorption in Healthy Unweaned Calves as an Indirect Measurement of the Oroduodenal Transit Rate of Liquid Meals

Abomasal emptying plays an important role in the incidence of digestive problems in calves. Our aim was to evaluate the acetaminophen absorption test (APAT) for characterization of the oroduodenal transit (ODT) of liquid meals in unweaned calves. Six healthy, unweaned Simmental x Red Holstein crossbred calves were involved in the project. The study was performed in three blocks at 3, 6 and 9 weeks of the calves' age. Within blocks, APAT was performed twice at an interval of at least 24 h. Once per each block, liquid transit was carried out with non-coagulating electrolyte solution (NES). The second test within a block was performed either while atropine sulphate was administered (block I), or by feeding a coagulating milk replacer (block II), or by administration of NES by ruminal tube (block III). Data were compared within and among blocks. Significant differences of several APAT traits were present for the different types of feeding, the different types of meals, the administration of atropine sulphate and the different ages of the calves. The emptying index T(max)/C(max) was suggested to be a valuable kinetic parameter for the characterization of ODT in these calves. We conclude that APAT represents a valid technique for characterization of ODT of liquid meals in healthy unweaned calves and may be a valuable tool for the evaluation of the reticular groove mechanism, the abomasal emptying and the absorption capacity of the duodenum.

Comparison of the rates of disintegration, gastric emptying, and drug absorption following administration of a new and a conventional paracetamol formulation, using gamma scintigraphy

PURPOSE

To investigate the hypothesis that faster drug absorption from a new paracetamol formulation containing sodium bicarbonate compared to that from a conventional formulation results from a combination of enhanced gastric emptying and disintegration/dissolution.

METHODS

Each formulation was administered in both fasted and fed states to 12 healthy volunteers. Gastric emptying and disintegration times were assessed by gamma scintigraphy, and serum paracetamol concentrations were determined by HPLC.

RESULTS

The mean time to complete disintegration of the new tablets was faster than that for conventional tablets in both fasted (10.2 min vs. 22.5 min) and fed (14.3 min vs. 46.4 min) states, although this difference was statistically significant in the fed state only (p = 0.0053). Mean gastric emptying times for the new tablets, as measured by t50 and t90, were also faster than those for conventional tablets in both fasted (t50 = 22.4 min vs. 47.5 min, t90 = 30.9 min vs. 64.1 min) and fed (t50 = 76.9 min vs. 106.4 min, t90 = 152.7 min vs. 155.5 min) states, although these differences were not statistically significant. Two subjects showed dramatically retarded gastric emptying of the new tablets in the fasted state: if these atypical data are excluded, the differences in both t50 and t90 in the fasted state are significant (p = 0.0110 and 0.0035, respectively). Rate of paracetamol absorption reflected the gastric emptying profiles as shown by significant correlation of emptying times with partial AUC.

CONCLUSIONS

It would seem that a combination of faster disintegration and gastric emptying of the new tablets is responsible for the faster rate of absorption of paracetamol from PA compared to P observed in both this study and in previous studies. The differences in gastric emptying are more pronounced in the fasted state, and the differences in disintegration are more pronounced in the fed state.

Erythromycin accelerates gastric emptying in a dose-response manner in healthy subjects

STUDY OBJECTIVES

To evaluate whether a dose-response curve exists for erythromycin, determine the lowest effective dose of erythromycin needed to improve gastric motility, and compare erythromycin's effectiveness with that of metoclopramide in improving gastric emptying.

DESIGN

Randomized, crossover, multiintervention trial.

SETTING

Inpatient clinical research center.

SUBJECTS

Ten healthy volunteers (four men, six women) from the general population.

INTERVENTION

On each study day, the subjects were infused with erythromycin 0.75 mg/kg, 1.5 mg/kg, or 3.0 mg/kg; metoclopramide 10 mg; or placebo, in random order. Subjects then drank Ensure 200 ml mixed with acetaminophen 1.5 g. Gastric emptying was estimated by comparing the area under the curve after 60 minutes for acetaminophen absorption using four timed blood draws.

MEASUREMENTS AND MAIN RESULTS

Erythromycin increased gastric emptying in a dose-response manner. Erythromycin 3.0 mg/kg and metoclopramide 10 mg were associated with statistically significant increases in liquid gastric emptying compared with placebo. During infusion, nausea and stomach cramping were associated with the 3.0-mg/kg dose of erythromycin; drowsiness was associated with metoclopramide.

CONCLUSION

In patients requiring intravenous erythromycin for gastric motility, the 3.0-mg/kg dose seems the most effective, with a reasonable side effect profile.

Activated charcoal alone or after gastric lavage: a simulated large paracetamol intoxication

AIMS

Activated charcoal is now being recommended for patients who have ingested potentially toxic amounts of a poison, where the ingested substance adsorbs to charcoal. Combination therapy with gastric lavage and activated charcoal is widely used, although clinical studies to date have not provided evidence of additional efficacy compared with the use of activated charcoal alone. There are also doubts regarding the efficacy of activated charcoal, when administered more than 1 h after the overdose. The aim of this study was to examine if there was a difference in the effect of the two interventions 1 h post ingestion, and to determine if activated charcoal was effective in reducing the systemic absorption of a drug, when administered 2 h post ingestion.

METHODS

We performed a four-limbed randomized cross-over study in 12 volunteers, who 1 h after a standard meal ingested paracetamol 50 mg kg(-1) in 125 mg tablets to mimic real-life, where several factors, such as food, interfere with gastric emptying and thus treatment. The interventions were activated charcoal after 1 h, combination therapy of gastric lavage followed by activated charcoal after 1 h, or activated charcoal after 2 h. Serum paracetamol concentrations were determined by h.p.l.c. Percentage reductions in the area under the curve (AUC) were used to estimate the efficacy of each intervention (paired observations).

RESULTS

There was a significant (P<0.005) reduction in the paracetamol AUC with activated charcoal at 1 h (median reduction 66%, 95% confidence intervals 49, 76) compared with controls, and a significant (P<0.01) reduction for gastric lavage followed by activated charcoal at 1 h (median reduction 48.2%, 95% confidence interval 32.4, 63.7) compared with controls. There was no significant difference between the two interventions (95% confidence interval for the difference -3.8, 34.0). Furthermore, we found a significant (P<0.01) reduction in the paracetamol AUC when activated charcoal was administered 2 h after tablet ingestion when compared with controls (median 22.7%, 95% confidence intervals 13.6--34.4).

CONCLUSIONS

These results suggest that combination treatment may be no better than activated charcoal alone in patients presenting early after large overdoses. The effect of activated charcoal given 2 h post ingestion is substantially less than at 1 h, emphasizing the importance of early intervention.