Semi solids such as creams, lotions, gels, and ointments require homogeneity in order to work properly, and maintaining proper homogeneity begins in the semi solid manufacturing process.

Though semi solid products may not command the same share of the pharmaceutical marketplace as solid dosages and injectable medications, semi solid manufacturing is still a burgeoning industry that continues to grow as end-users come to rely on the kinds of customized dosages which can be easily delivered by semi solids.

With consumers becoming better educated and with more information at their fingertips thanks to the internet and mobile devices, end-users expect more personalized healthcare, including the ability to select medication dosages that are tailored specifically to them, a niche that semi solids are uniquely poised to fill. However, semi solids require homogeneity in order to work correctly, and there are many factors that can affect homogeneity during semi solid manufacturing.

What is homogeneity and how can it be maintained throughout semi solid manufacturing?

Properties Affecting Homogeneity in Semi Solid Manufacturing

Semi solid pharmaceutical products include gels, ointments, lotions, and creams. Many begin with an oil phase and a water phase. In these two phases, the various ingredients that will form the semi solid compound are mixed together. One key element of semi solid manufacturing that is not present as often in other types of pharmaceutical manufacturing is the need for homogeneity.

Homogeneity–defined as “the state of being all of the same kind”–means that the ingredients of a semi solid compound need to be evenly distributed throughout the product, not just during manufacturing but through packaging, distribution, and use. To put it another way, the proportional distribution of the API in a lotion or cream must be the same in a 1,000 gallon tank at the CMO as it is in a 1 ounce tube in the end-user’s first aid kit.

Guaranteeing homogeneity requires that semi solid manufacturers do more than maintain quality control throughout the manufacturing process. Steps must be taken to ensure that semi solid products will maintain their homogeneity once they’re packaged, shipped, stored in an end-user’s medicine cabinet, and, ultimately, applied.

What can affect homogeneity during the semi solid manufacturing process–and what can be done about it?

Properties Affecting Homogeneity in Semi Solid Manufacturing

Problems in the homogenization process at the manufacturing facility can lead to problems with the homogeneity–and therefore the effectiveness–of the product down the road. Common problems include flow restriction during the semi solid manufacturing process as well as incomplete mixing during oil and water phases. Following cGMP and using standards such as Quality by Design (QbD) can help semi solid manufacturers avoid running into these kinds of difficulties in the production line, which can result in diminished effectiveness or other problems with the end product.

Homogeneity is only one of the factors that affects the quality and effectiveness of semi solid products. Particle distribution, spreadability, level of grit, and use of surfactants are all important factors in determining the quality and the shelf life of semi solids. And all of them can be controlled for or guarded against during the manufacturing process.

Packaging is an important consideration for semi solid manufacturers. Not only does packaging need to help maintain the purity and homogeneity of the product, the reliance on OTC sales in the semi solid marketplace means that a variety of different sizes and types of packaging are needed to remain competitive.

CMOs working with semi solids that require large amounts of alcohol in their formulation also face unique challenges such as explosion-proofing their facilities in order to stay up to code or installing dedicated feeding tanks to prevent flow restriction and ensure proper mixing throughout the manufacturing process.

What does homogeneity mean for the business of semi solid manufacturing?

A homogenous semi solid product is one that will do what it is intended to do in the dosage that is intended to be used, full stop. If the product separates out during storage, the end user may receive less of the API than intended, even though they’re using the proper dose. Considering that many semi solid products are sold OTC and designed to be applied at home rather than in a clinical setting, the necessity of proper and transparent dosage is even more important.

With so many semi solid products available over-the-counter, customers who find one product to be unreliable will quickly switch to another. Maintaining homogeneity throughout the semi solid manufacturing process leads to safer more reliable products which, in turn, leads to bigger business for manufacturers.