News

Polytetrafluoroethylene (PTFE) coatings are frequently used on Dissolution bath accessories. Many individual monographs specify this coating on Sinkers, Baskets, Paddles and Vessel interiors. The coating on the accessories can, over time, develop chips or scratches that can expose the substrate to corrosion and affect the results of the test. Technicians handling these coated parts should be familiar with the following guidelines to help extend their service life. Parts with corrosion should be removed from service.  Handling The PTFE coatings are applied at the factory in order to maximize adhesion and durability. The coating, however, is susceptible to chipping and scratching...

The following article has been authored by John Heaney. Push-on style baskets have been used for dissolution testing for quite a few years at this point.  While they’re generally accepted as equivalent to the clip style baskets pictured in USP <711>, it’s important to be aware of the differences between the two designs.  Both have some advantages and disadvantages depending on the method. The clip style is officially recognized in <711>, so there is never any debate as to whether the clip style baskets are acceptable for testing.  Furthermore, all the wetted materials are 316 Stainless Steel, which is chemically...

  The following article has been authored by John Heaney. Intrinsic dissolution is a specific niche of dissolution testing often reserved for early R&D.  The purpose is to provide scientists with an idea of the solubility of the API they’re studying.  This data can be invaluable as it will help determine the excipients required to develop an oral dosage form. There are 2 types of methods for this.  The first is a Rotating Disk (often called the Wood’s Apparatus) and the second is Stationary Disk.  In both cases a pellet of the pure drug is pressed into a drug compact...

The following article has been authored by John Heaney. While automation is prevalent with dissolution testing, manual testing can and still should be done in certain circumstances.  This can be when automation is too expensive, when the method is being developed and a certain amount of flexibility is needed, or when sample times are too short to be completed by automated systems.  Manual sampling does offer significant flexibility but it also has some factors that need to be considered to ensure consistency. Sampling height is clearly defined in USP <711> as half-way between the top of the apparatus, be it...

The following article has been authored by John Heaney.   Compared to dissolution Apparatus 1 (Baskets) and Apparatus 2 (Paddles), Dissolution Apparatus 3: Biodissolution (the reciprocating cylinder) is quite rare.  However, it has some key advantages over the more common baskets and paddles which can make it very useful for key applications. Apparatus 3 consists of a glass cylinder with a mesh screen at the bottom moving up and down in a specified distance and rate within a glass dissolution vessel.  The dosage form is held within the glass cylinder.  Vessels are typically arranged in rows allowing the glass cylinder...