Basket method

Figure 1 Rotating basket method. Source From Ref. 10.

A common feature of widely used apparatus like the paddle or basket method is their limited volume. Typical volumes used in these systems range from about 500 to 4000 mL, limiting their use for very poorly soluble substances. Theoretically at least, open systems may be operated with infinite volumes to complete the dissolution of even very poorly soluble com-... 

Fluid velocities using the basket method were determined to range between 0.3 and 5 cm/sec [25-200 rpm], and for the paddle method, between 1.8 and 37 cm/sec [25— 200 rpm]. Possible applications of these fluid velocity data may include their use to forecast in vitro dissolution rates and profiles of pure drug compounds for the paddle test employing an appropriate mathematical scenario/formula like the combination model. 

The release kinetics from the tablets of the drug-polymer complexes were carried out in buffered release media containing 0.01 M phosphate and NaCl ranging from 0.2 M to 0.02 M at 37°C by the USP basket method at 100 rpm. Drug release was monitored on a HP 8452A diode-array spectrophotometer at 250, 306, 306, 270, 278, 278, and 274 nm for sodium diclofenac and sulfathiazole, labetalol HCl, propranolol HCl, verapamil HCl, and diltiazem HCl, respectively. 

USP Apparatus I (basket method) preferred for capsules and dosage forms that tend to Loat or disintegrate slowly... 

FIGURE 12 Various drag dissolution methodologies, (a) In the paddle method, the tablet is placed in the dissolution vessel containing dissolution medium and the paddle is rotated at defined rpm, while the dissolution vessel is maintained at body temperature, (b) In the basket method, the tablet is kept inside a meshed basket and rotated, (c) For IDR studies, the tablet is kept inside a die cavity and only one face of the tablet is exposed to the dissolution medium. 

Figure 12.2 The rotating basket and rotating paddle versions of the official method for dissolution testing of solid oral dosage forms, (a) The rotating basket - method 1, USP/NF. This method is official for USP/NF and BP. Current specifications describing geometry and positions for each compendium are shown, (b) The rotating paddle - method 2, USP/NF.

Dissolution testing of indapamide is accomplished using the rotating basket method (USP Method I) with 900 mL of simulated gastric fluid T.S. without enzymes heated to 37<>C as the dissolution medium and a basket rotation of 100 rpm. Samples are placed in the baskets and the baskets are then lowered into the dissolution medium with samples withdrawn at appropriate intervals. The samples are filtered through 0.45 pm Miilipore filters. The dissolution medium is assayed for indapamide against appropriate standards using an UV absorbance assay (23). 

As a general guideline in the choice of dissolution test apparatus, the simplest and most well-established method should be chosen, with respect to both in-house know-how and regulatory aspects. In most cases, this is the USP II paddle method or the USP I rotating basket method. However, if satisfactory performance cannot be obtained by these methods, others should be considered. Primarily, the USP III and USP IV methods, and non-compendial methods could also provide relevant advantages. 

Dissolution tests using the basket method (50/100 rpm) or the paddle method (50/75 rpm) under mild test conditions are used to generate a dissolution profile at 15-minute intervals. The pH range is 1.2-6.8 pH up to 8.0 may be tested with justification. The temperature is 37 0.5 °C. Methods are described in the US Pharmacopoeia. Test requirements vary depending on solubility of drug products. In vitro test may need validation to confirm in vivo results. 

Fig. 5.15 Release of 5 6)-carboxyfluorescein from chitosan capsules, determined by the J.P. rotating basket method. Key ( ) liquid 1 (j. P.) liquid 2 (j.P.) 33% suspension of cecal contents (O) phosphate-buffered saline (pH 6.0). Results are expressed as the mean+SE of two to four experiments.

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