The influence of drug and diluent particle size on the in vitro release of drug from hard gelatin capsules

To investigate the influence of machine operating variables on formulations derived from lactose types in capsule filling: part 2

This study is the second in a series that examines the characterizing and selection of suitable grades of lactose for capsule formulation development. Based upon the previous study, four grades were selected for further study. The effects of drug load and operational variables on formulations derived from these four lactose types were evaluated for physicochemical and mechanical attributes of plugs and their capsules on an instrumented dosing-disc capsule filling machine (H&H KFM/3) using acetaminophen as a model, highly soluble and poorly compressible drug. The results obtained were as follows: (1) flowability reduced upon increasing drug load; (2) powder bed height (PBH) and compression force (CF) had positive significant effect on plug weight (p < 0.05); (3) ejection force was positively and significantly correlated with increasing speed and CF (p < 0.05); (4) AL capsule plugs had the highest plug crushing force which was followed by DCL15; (5) the crushing strength of plugs made from DCL11 increased with increasing acetaminophen concentration; (6) higher CF had a significant negative impact on acetaminophen release at 15 min time point (p < 0.05); (7) at 10% and 40% drug load, formulations containing AL showed the quickest drug release; and (8) increased drug load had a significant negative impact on the release rate at 15 and 45 min time points (p < 0.05). Overall, the results from this study provides information on risk based assessment of filler selection based on drug load and the range of machine operating variables which will help in defining criteria for meeting key quality attributes for capsule formulation development.

Application of hydroalcoholic solutions of formaldehyde in preparation of acetylsalicylic acid gastro-resistant capsules

Enteric coating of hard gelatin capsules by application of hydroalcoholic solutions of formaldehyde was studied and developed in accordance with previous publications. It is possible to affirm that this coating constitutes a simple, stable, reproducible, and inexpensive method, being a valid alternative to those which have been proposed. The aim of the present investigation is the preparation of acetylsalicylic acid gelatin capsules with good conditions of gastro-resistance and enteros solubility.

Review article: mechanisms of drug release from tablets and capsules. 2. Dissolution

Optimal drug dissolution is crucial to the success of oral drug therapy. Slow dissolution has frequently been correlated with poor or erratic performance of oral dosage forms in vivo, and drugs of low aqueous solubility provide a major challenge to the designer of modern oral dosage forms. In this second of two reviews, we briefly describe the physical process of dissolution, the principal factors controlling drug dissolution from tablets and capsules, and the strategies that are utilized by pharmaceutical scientists to enhance drug dissolution of orally administered drugs.

The angle of internal flow as an indicator of filling and drug release properties of capsule formulations

The cohesiveness of size fractions of acetylsalicylic acid and lactose alone and in various combinations has been determined by estimation of the rate of decrease in volume as a function of tamping under standard conditions. The cohesiveness was quantified in terms of empirically derived characteristic, the angle of internal flow phi. The value of phi was found to decrease with the particle size of acetylsalicylic acid, but not lactose, and was found to be dependent on the relative proportion and particle sizes of acetylsalicylic acid and lactose when blends of powder were studied. The value of the time for 50% of the drug content to be released from a hard gelatin capsule in an in-vitro dissolution test, T50, was found to decrease with decreasing values of omega for capsules containing acetylsalicylic acid alone. For capsules containing powder blends there was no consistent relationship between the value of T50 and phi.

The influence of pH of dissolution fluid and particle size of drug on the in-vitro release of drug from hard gelatin capsules

The influence of pH of the dissolution fluid on the in-vitro release of acetylsalicylic acid from hard gelatin capsules has been studied for a series of particle size fractions of the drug. Generally, the time required for 50% of the drug content of the capsule to appear in solution during a dissolution test, T50, increased as the pH increased from 1.2 to 2.0; thereafter the value of T50 decreased as the pH increased from 3 to 7. These changes were found to be related to the apparent solubility of the drug. The extent of the changes was found to be further dependent on the particle size of the drug. For capsules filled with particle size fractions of 2.5 and 5.5 microns median diameter, the changes were small. Larger changes were observed with particles of median diameters of 45, 100, 220 and 330 microns while the largest changes (greater than two-fold) were obtained with particles of median diameter 130 and 430 microns. The type of kinetics that could be used to express the release rates was found to be particle size-dependent. For particles of 45 microns and larger, the release rate followed an apparent zero order process while an apparent first order process represented the release for the two smallest particle size fractions.

The prediction of the bulk densities of powder mixtures, and its relationship to the filling of hard gelatin capsules

From measurements of the properties of individual components, it has been found possible to predict the maximum tapped bulk density of two component mixtures of a range of particle size fractions of acetylsalicylic acid and lactose in varying proportions. This has been extended to the prediction of bulk density of such mixtures when filled into hard gelatin capsules by a system which results in the powders existing at the maximum tapped bulk density. Consequently the capsule fill weight can also be predicted for such systems. The method is less satisfactory for the prediction of the bulk density and capsule fill weight, when the capsules are filled by a process involving compression of the powder within the capsule shell.