In-vitro drug release testing is a measure of the release of an active pharmaceutical ingredient (API) in the laboratory environment from the drug product matrix. Drug release testing is an essential key in drug development and quality control of a drug.
During the manufacturing of a pharmaceutical product, it mainly helps in assessing the differences between the prototypes. It also aids in predicting the time for the release of an API and modelling the in vivo behaviour. The in vitro conditions are generally selected to simulate the in vivo conditions. During the quality control, it is used to assess the conformance of a batch to the pre-determined criteria at the time of manufacturing a drug. It also assesses the API release stability in the long term.
The in-vitro testing, during this phase, can determine and reflect the change in API release profile that is eventually related to the drug product. This kind of drug testing is important in in-vitro testing and elution testing.
Types of Drug Testing
The drug testing is categorized into the following types:
- Oral dosage dissolution testing
This kind of drug testing measures the dissolution rates of the drug substance. The dissolution from a solid state to a liquid state per unit time, under the standardized conditions, is measured. Dissolution is mainly applied to the tablets, capsules, suspensions, topical substances, transdermals and drug-eluting stents.
- Topical and Transdermal in-vitro release testing (IVRT)
During this in-vitro testing process, the release of API from topical and transdermal products can be measured along with the subsequent permeation through a membrane. It can be done in a vertical diffusion cell. When making use of this apparatus, the formulation is applied or kept in contact with the receiving medium through a membrane.
The membrane is made up of a synthetic polymer, cadaver and tissue constructs. Based on the purpose of the tests done, the membrane is selected. This test is suitable not only for the topical formulations but also for the products that are delivered thru the other sources likes vaginal, rectal, buccal and nasal routes.
- Drug-device combination- in vitro evolution testing
The implantable devices deliver drugs that can be measured and determined with the help of drug device combination in vitro elution testing. By subjecting the implantable devices to soaking or stirring in a suitable medium the assessment can be done. Periodically sampling is done of a medium for quantitation to establish an elution profile.
With the use of a daily set period medium, elution testing can be done or with the medium circulating around the device. Depending on the nature of the device, the test volumes, choice of medium can be decided.
The dissolution or drug testing plays an important role for solid oral pharmacopoeial dosage forms in which absorption of the drugs is a must. The absorption of the drugs is important for the products to exert the desired therapeutic effect.