Apparatus

For a dissolution test to be used universally to control the consistency of a pharmaceutical dosage form, some controls must be placed on the type of apparatus used. The USP XVIII and NF XIV described only three types of apparatus [1], but more recent developments in dissolution testing have resulted in seven types of apparatus approved for use in the USP 23/NF 18 [7], USP apparatus Type 1 and Type 2 are by far the most frequently used for immediate release and most sustained release dosage forms. These types are described in some detail below. USP Type 4 in used rather infrequently in the United States, but finds more use in the European community. USP Types 3, 5, 6, and 7 are much less frequently used and only a brief description is given below. Compendia other than the USP, e.g., the Pharmacopoeia of Japan (JP) [8], the British Pharmacopoeia (BP) [9], and the European Pharmacopoeia (EP) [10] all contain the same basic Type 1 and Type 2 dissolution equipment as described in the USP. The BP and EP also include a flow-through apparatus identical to the USP Type 4 apparatus.

This apparatus, shown schematically in Figure 1, consists of a covered vessel of specified shape and dimensions and capacity of 1000 ml, a metallic shaft one end of which attaches to a motor, and a cylindrical metallic mesh basket that attaches to the opposite end of the shaft. The dosage form is placed inside of the basket and the basket assembly is immersed in the dissolution vessel containing a nominal volume of dissolution medium and rotated at a specified speed.

Figure 7.1

USP Apparatus 1, Rotating Basket. Royal Hanson]

STANDARD

• 40 MESH STAINLESS

MODIFICATIONS

• BASKET DIMENSIONS

• pH CHANGE DURING TEST

• SURFACTANTS IN MEDIA

USEFUL FOR

• MODIFIED RELEASE

DOSAGE FORM

Figure 7.1

USP Apparatus 1, Rotating Basket. Royal Hanson]

[Reproduced with permission of b) USP Type 2

The USP Type 2 is currently the most frequently used apparatus for all solid dosage forms. The dissolution vessel used with this apparatus is the same as for the USP Type 1 apparatus. However, the basket assembly is replaced by a paddle of specified dimensions, shown schematically in Figure 2. With this apparatus, the dosage form is dropped directly into the vessel containing the dissolution medium and allowed to sink to the bottom; the paddle is then rotated at a specified speed but can be immersed in the vessel when the dosage form is dropped as long as the rotation device is switched off, which is the common industry practice. The USP specifies to place the dosage form in the apparatus and immediately operate at a specified speed. The USP does not state whether the paddles can or cannot be immersed prior to addition of the dosage form, only that the rotation be started after the dosage form has been added.

STANDARD

• TEFLON OR STAINLESS

• WIRE SINKER FOR FLOATERS

MODIFICATIONS

• SURFACTANTS IN MEDIA

Floaters Dosage Form

USEFUL FOR

• MODIFIED RELEASE

• AS APPARATUS 5 (PADDLE OVER DISC)

• TRANSDERMAL PATCH

DOSAGE FORM

Figure 7.2

USP Apparatus 2, Paddle. [Reproduced with permission of Royal Hanson]

The USP Type 3 apparatus finds its primary use in extended release formulations, although it is not used extensively. It consists of a cylinder with a screen on one end that contains the dosage form and a larger glass cylinder into which the dissolution medium is placed. The dosage form-containing cylinder is immersed in the dissolution medium and agitated with vertical strokes.

FILTER

FILTER

Flow Through Cell Usp Apparatus

COLLECT SAMPLES

USEFUL FOR

• LOW SOLUBILITY DRUGS

• RAPID DEGRADATION

VARIATIONS

• OPEN/CLOSED SYSTEM

MEDIA SOURCE

Figure 7.3

USP Apparatus 4, Flow-through Cell. [Reproduced by permission of Royal Hanson]

Was this article helpful?

0 0

Post a comment