Influence of Excipients

The freezing of complex organic solutions and suspensions is often difficult to predict theoretically. The methods to analyze the freezing process and the structure formed are described in Section 1.1.5. The freezing is influenced by several factors, which often act in opposing directions  

2 N umber and geometry of foreign particles, which influence the heterogeneous nu-cleation the closer their structure is similar to the ice structure, the better is their effectiveness as nuclei. 

3 The degree of subcooling, which depends on the substance, but is strongly influenced by the two points above. 

4 The rate of growth of the ice crystals, which depends on temperature and the viscosity of the solution the latter increases strongly with increasing concentration of the solution. 

5 That part of the water which is not frozen due to high freezing rate forms highly viscous occlusions in between the ice crystals. 

---

Levina, M., and Rajabi-Siahboomi, A. R. (2004), The influence of excipients on drug release from hydroxypropyl methylcellulose matrices,/. Pharm. Sci., 93, 2746-2754. 

Thoma s interests included methods of testing (76-78), the influence of excipients and formulations on the photostability of products (71,79-83) and methods of photoprotection via packaging (67,71,84-88) or formulation (67,89-91). Several of his papers dealt with specific photostability problems such as antibiotics (92) antimitotics (93-96), adrenaline (97), molsidomin (98), phenothiazines (99), quinolines (100) and nifedipine (101-107). 

Influence of excipient on the overall quality, stability, and effectiveness of drug product. 

Du J, Hoag SW. The influence of excipients on the moisture senstitive drugs aspirin and niacinamide comparison of tablets containing lactose monohydrate with tablets containing anhydrous lactose. Pharm Dev Tech 2001 6(2) 159-166. 

TEER experiments, but also drug transport experiments, are very sensitive to how one manipulates the filter inserts. Therefore, the experimental set-up should always include the proper control conditions to assess the influence of any manipulation to the cells. Care should be taken not to disturb the cells on the filter to much prior to the experiment so it is for instance better not to change the medium on the filters to apply a solution of active compounds, but rather to apply the compounds in a small volume (as a rule we apply no more than 30 pi) of a concentrated stock solution to the existing medium. In addition, the influence of excipients (ethanol, DMSO, etc.) can be very strong, also on the expected effect of a stimulus, so these should be kept below... 

Thoma, K. and Kiibler, N. (1997) Influence of excipients on the photodegradation of drug substances, Pharmazie, 52, 122-129. 

J. Sawicka, The influence of excipients and technological process on cholecalciferol stability and its liberation from tablets, Pharmazie 46, 519-521 (1991). 

Chitosan (molecular weight, 19-400 kDa degree of deacetylation, 75-98%) has been evaluated as a directly compressible vehicle for tablets, but has found limited utility due to the lack of good flow properties and compressibility. The influence of excipient (lactose, sodium lauryl sulfate, sodium alginate, hydroxypropyl methyl... 

M. Levina, A.R. Rajabi-Siahboomi, The Influence of excipients on drug release from hydroxypropyl methylceUulose matrices, J Pharm Sci, 93 2746-2754, 2004. 

T. Kristmundsdottir, K. Ingvarsdottir, G. Saemundsdottir, Chitosan matrix tablets The influence of excipients on drug release. Drug Dev Ind Pharm, 21 1591-1598 1995. 

The influence of the actual manufacturing process can also affect the contribution of the diluent to the final characteristics of the product. For instance, Shah et al. [45] demonstrated that the release of drug from tablets formulated with soluble excipients may be more... 

The dose of the drug and its solubility are important considerations in the design of the formulation. The amount and type of active ingredient influences capsule size and the nature and amount of excipients to be used in the formulation. Larger-dose drugs that must be granulated to produce tablets may be more easily direct-filled into hard shell capsules with proper choice of excipients. 

Other workers have used the tristimulus parameters to study the kinetics of decomposition reactions. The fading of tablet colorants was shown to follow first-order reaction kinetics, with the source of the illumination energy apparently not affecting the kinetics [49]. The effect of excipients on the discoloration of ascorbic acid in tablet formulations has also been followed through determination of color changes [50]. In this latter work, it was established that lactose and Emdex influenced color changes less than did sorbitol. 

Also the influence of the adjustable variables (disintegrant concentration and storage temperature and relative humidity), on the SIR of disintegration time (SIR(D)) was calculated for each combination of disintegrant and filler-binder. This was expressed as in equation (10). The coefficients of the equations for the different combinations of excipients are given in Table 8.9. 

Shah AC, Mlodozeniec AR. Mechanism of surface lubrication Influence of duration of lubricant-excipient mixing on processing characteristics of powders and properties of compressed tablets. J Pharm Sci 1977 66 1377-1381. 

In this study, the influence of several formulation factors on the release kinetics of potassium chloride from directly compressed matrices is investigated. Formulations containing hydrophilic (methylcellulose, carbomer), plastic (polyvinyl chloride) and wax (glycerol palmitostearate) matrix materials at concentrations of 10%, 15% and 20%, and insoluble excipients, were prepared and tested using the USP XXI-NF XVI rotating paddle method. 

The results show, that release profiles never followed a tm law (equation (1)). A marked influence of the excipient s viscosity grade or dissolution rate on drug release is further observed. The swelling profiles for matrices containing low-viscosity or BSA are shown in Figs 4-6. The profiles show that maximum swelling is always observed in cases of quick dmg depletion and bent... 

In the case of a high dissolution rate of excipient and/or high matrix loading, strong initial swelling, rapid depletion of matrix excipient and consequently depletion of the elastic matrix pores occur. This should lead to curved release plots. It is noteworthy that swelling maxima have no influence on release profiles obviously, therefore, excipient is released from zones of the matrix already drug depleted. 

---