Semi-solids form an important part of the Penn portfolio. Approximately 20% of our development work is semi-solid based (creams, gels and ointments).

Penn has been manufacturing semi-solids for almost 20 years. Our present manufacturing portfolio of products contains commercial semi-solids products for which Penn is heavily involved in all the development activities as well. In addition, members of our Formulation team have extensive experience of semi-solids formulation. We are currently collaborating with new clients who are developing semi-solids, and we are working with 5-200Kg scale with these particular products.

Scale
We are able to develop and manufacture semi-solids on a scale of a few grams to 450Kg. On the small scale we work with stainless steel containers, water and steam baths and stirrers but we also have access to equipment at the 4-8Kg scale (Brogli), 40Kg scale (Kreiger) and 450Kg scale (Barvick). All three pieces of equipment have the same mode of operation which makes for ease of scale up to industry standard guidelines.

We are able to pack into collapsible aluminium tubes, plastic laminate tubes or tubs up to small scale commercial batch size.

The Penn offering
Because we have worked on a wide variety of semi-solid products we are able to offer this wealth of experience to new clients. In addition to the formulation, process development and scale up expertise we are also able to support the development with analytical resources. We also have vast experience in manufacture, packaging and distribution of clinical trial supplies if required. Penn is unique in that all these resources are located on a single site so facilitating communication and helping to reduce development time scales.

Potential difficulties
Usually the development of ointment formulations is reasonably uncomplicated. The dosage form is a single phase and hence seperation is not usually an issue. The ointment is anhydrous and so microbiological and preservation difficulties are obviated.

If the API is heat sensitive then the process has to be developed to minimise the exposure of the active to high temperatures. If the API is suspended in the ointment base then uniformity issues have been to be considered. Additional excipients can be added which help to address this problem.

If the API dissolves in the non-aqueous base then the possibility of re-crystallisation needs to be addressed as thsi could lead to a change in polymorphic form.

Analytical Support
As a result of the experience outlined in our formulation overview, Penn Pharmaceutical Services has developed a comprehensive support service for topical products. This includes extensive range of HPLC systems and detection methods including Mass Spectromertry. In addition to these more general techniques, our team has practical experience of more specific in-house techniques associated with semi-solids such as microscopy, viscosity and lacquer integrity testing for laminate tubes.

Such experience is supported by a full range of ICH stability storage and associated analytical method development and validation. These systems have been specifically subjected to FDA PAI on several occasions with successful outcomes.