Coating dissolution profiles

Hydroxypropyl Above pH 4.5 Optimal dissolution profile for enteric coating... 

Figure 26 shows a comparative study of uncoated tablet and sugar-coated tablet after a barrier to water with copovidone 0.5 mg/cm2 of the warm tablet cores using a 10% solution in ethanol. During two years the coating tablets (with initial humidity 2.5%) remained stable and dissolution profiles were similar to the initial time with similarity f2 = 82 observed and friability decreased from 0.25% (uncoated cores) to 0.02% (coated tablets). 

Dissolution Profile SEPIFILM LP can efficiently improve the moisture barrier on moisture-sensitive active pharmaceutical ingredients (API) or hygroscopic cores. The breakthrough in this technology is that SEPIFILM LP does not modify the dissolution profile when compared to conventional coating (Figure 30). 

FIGURE 35 Dissolution profile of coated and uncoated ranitidine HC1 tablets. 

Pharmacopoeias generally do not require a dissolution profile to be determined but do specify that a certain amount of drug must dissolve (or not dissolve in the case of enteric-coated products) within a specified time. Should a single-time specification be stated, the test may be concluded in a shorter time if the requirement for a minimum amount dissolved is met. If two or more times are specified, then the samples should be withdrawn with a tolerance of 2% of the stated time. For Digoxin Tablets BP, when there is more than one tablet per test, all six replicate runs should release at least 75% of the stated amount within 60 minutes. 

Schmidt, P.C. Niemann, F. The miniwid-coater. HI. Effect of application temperature on the dissolution profile of sustained-release theophylhne pellets coated with eudragit RS 30 D. Drug Dev. Ind. Pharm. 1993, 19, 1603-1612. 

In one paper by Kirsch and Drennen [62], three experiments were performed on coated tablets. In the first experiment, intact theophylline tablets coated with an ethylcellulose polymer were analyzed by acousto-optic tunable filter (AOTF) spectrometers. Tablets were coated with increasing levels of ethylcellulose to vary the dissolution profiles. After spectra were collected, the dissolutions were run on a U.S.P. Type II dissolution apparatus. The time required for 50% of the drug to enter solution was used as the measure of dissolution rate. Principal component (PC) regression was used to develop the calibration. This gave a SEE of 2.8 min, a coefficient of variation of 0.977, and a SEP of 6.6 min the time to 50% dissolution ranged from 48 to 93 min. 

Figure 5 In vitro dissolution profile of different dosage forms at pH 6.8, simulating the small intestine. Dosage forms that are film coated with an enteric polymer, EUDRAGIT L, (SalofaUc, Claversal), show a delay in drug release at the dissolution pH of the polymer, which is probably due to the higher amounts of polymer that are applied (Rudolph et al., in press). Other film coatings Pentasa (Ethylcellulose), Ascacohtin (EUDRAGIT S 100).

J. R. Hoblitzell, K. D. Thakker, and C. T. Rhodes, Effects of moderate stress storage conditions on the dissolution profile of enteric-coated aspirin tablets, Pharm. Acta Helv. 60.28-32 (1985). 

The dissolution profile of some coated pellets was investigated as a function of pH, buffer concentration and stirring speed. Using a pharmacopoeial dissolution apparatus of 7 stirred vessels, 7 experiments may be carried out in one run. However all 7 of these experiments must be at the same stirring rate, as it is not possible to stir the individual flasks independently of one another. 

Table 5.23 Uniform Shell Design for Characterising the Dissolution Profile of Coated Pellets, as Function of pH, Buffer Concentration and the Stirring Speed... 

Typically, these additives are used as binders, coating agents, or carrier materials for liquids. But they might also be necessary to achieve sufficient chemical stability (see example for aerial bleach catalyst in Ref. 92), improve the dissolution profile, or simply for esthetic reasons (see example for PAP in Ref. 93). 

Fig. 4.13 Dissolution profiles of API from PVP K30 and Eudragit LlOO surface coatings in pH 7.4 phosphate buffer, respectively (T = 37 °C). USP basket method, 100 RPM...

---