Correlation of In Vitro and In Vivo Methodology for Evaluation of Antacids

Smyth, Robert D.; Herczeg, T; Wheatley, Thomas; Hause, Welland A.; Reavey-Cantwell, Nelson H.

doi:10.1002/jps.2600650722

Cited by 12 publications

(5 citation statements)

References 8 publications

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“…It was decided that useful duration of action would be up to 4 h (18,19) and areas should be calculated under the curve only up to this value; our results, however, indicate that no product was active in excess of 3 h. No attempt was made to measure rate of onset of action since, in all the products tested, the effect was immediate and this is supported by earlier findings (8).…”

Section: Discussionsupporting

confidence: 73%

“…Although Smyth er al. (8) described procedures for estimating the onset, rate and duration of antacid neutralization, previous and subsequent investigators have relied upon neutralizing capacity in comparing the efficacy of antacid preparations. Antacids which raise 1, 7), and maintain it at that level until the contents have passed out of the duodenum, are likely to act in the most therapeutically beneficial manner.…”

Section: Discussionmentioning

confidence: 99%

“…A number of methods for assessing in vUro antacid effectiveness have been described in the literature (6)(7)(8)(9)(10)(11)(12)(13)(14) and in some the results have been shown to correlate well with in vuro data (7,8).…”

Section: T D Duffy Et Almentioning

confidence: 99%

“…When the pH is raised above 3 most of the gastric hydrochloric acid is neutralized and the proteolytic activity of pepsin (which is capable of digesting the mucosal membrane) is reduced. Previous comparative assessments of antacids have recognized this fact and have either measured the cumulative volume of acid required to maintain the p H at 3 (7, 9,10,11) or have measured the ability of antacids to maintain the pH above 3 during titration with acid (8,15).…”

Section: T D Duffy Et Almentioning

confidence: 99%

See 3 more Smart Citations

A Comparative Evaluation of Liquid Antacids Commercially Available in the United Kingdom

et al. 1982

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Twenty-six liquid antacids have been assessed using a procedure which permits comparisons to be made in terms of 'antacid efficiency' parameter which reflects both the ability to maintain pH above 3 and the duration of the effect. A wide variation in activity was demonstrated in the preparations tested and it was concluded that antacids could be classified into four categories according to potency.

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Section: Discussionsupporting

confidence: 73%

Section: Discussionmentioning

confidence: 99%

Section: T D Duffy Et Almentioning

confidence: 99%

Section: T D Duffy Et Almentioning

confidence: 99%

See 2 more Smart Citations

A Comparative Evaluation of Liquid Antacids Commercially Available in the United Kingdom

et al. 1982

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“…Titration at pH 3.0, as proposed by Fordtran [12], obviously failed to meet this requirement. However some authors have reported good correlations between in vitro and in vivo data [38,48,58].…”

Section: Effect Of Antacid Adhesion To the Gastric Mucosa On Antacid mentioning

confidence: 99%

Interests of the ‘artifical stomach’ techniques to study antacid formulations: Comparison with in vivo evaluation

Vatier

Celice-Pingaud

Farinotti

1998

Fundamemntal Clinical Pharma

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In this overview, the methods for assessing antacid activity in vitro are surveyed, and the problems of their comparison with in vivo methods of evaluation are discussed. In vitro assessment is based on two types of method: static and dynamic. The static method of titration, with end-of-titration pH values ranging between 3.0 and 1.0, has been used to quantify the number of sites capable of binding H+ ions at each end-of-titration pH, and to identify certain chemical mechanisms involved in this binding; in other words, this approach provides the pharmacological characteristics of the drugs tested. In contrast, it does not take into account physiological factors modulating antacid activity, such as gastroduodenal fluxes (including gastric emptying), drug adherence to the mucosa, and acid secretion. The dynamic method was initially based on an artificial stomach model, which has gradually been upgraded to a computer-controlled artificial stomach-duodenum model. This model overcomes certain weaknesses of the static method by simulating flux and pH conditions in the gastroduodenal tract, by taking into account interactions with the gastric mucosa and thereby reproducing the in vivo medium encountered by antacids. It is therefore capable of reflecting the characteristics of antacids, namely their effect on gastric pH and resistance to acidification, at the same time helping to identify the underlying chemicophysical mechanisms. In vivo, the antacid effect can be assessed qualitatively by means of pH-meter studies in healthy volunteers, both in baseline conditions and during secretory stimulation, and also quantitatively by methods based on intragastric titration in response to a liquid meal (IGT). pH-meter studies in baseline conditions come up against the variability of the basal pH and antacid homogenization with gastric contents, which results in a wide range of individual values. This variability is found in pH-meter studies during pentagastrin infusion and, to a lesser degree, in response to a meal. Close correlations have, however, been established between results obtained with the artificial stomach model and in healthy volunteers submitted to pH-metric or IGT studies, with several antacids. It seems that the artificial stomach method is sufficiently reproducible to make it the method of choice for investigating the antacid activity of all drugs aimed at treating acid hypersecretion disorders. In contrast, in vivo studies may be warranted for precise therapeutic indications, such as treatment of duodenal ulcer or gastro-esophageal reflux, in which the therapeutic effect is judged on the basis of an improvement in symptoms and endoscopic criteria, without the need to demonstrate the antacid effect itself.

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Action of Hydrochloric Acid on Aluminum Hydroxide—Magnesium Hydroxide Gels and Magaldrate: 27Al NMR and pH-Stat Studies

Wilson

Falzone

Johnson³

et al. 1985

Journal of Pharmaceutical Sciences

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Correlation of In Vitro and In Vivo Methodology for Evaluation of Antacids

Cited by 12 publications

References 8 publications

A Comparative Evaluation of Liquid Antacids Commercially Available in the United Kingdom

A Comparative Evaluation of Liquid Antacids Commercially Available in the United Kingdom

Interests of the ‘artifical stomach’ techniques to study antacid formulations: Comparison with in vivo evaluation

Action of Hydrochloric Acid on Aluminum Hydroxide—Magnesium Hydroxide Gels and Magaldrate: 27Al NMR and pH-Stat Studies

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