The main difference between analytical methods for single entity combination products (SECPs) and traditional drug product formulations like oral or parenteral dosage forms is the sample preparation. For most methods the sample preparation will need to be developed to be unique and specific to the SECP but usually involves complicated multi-step procedures.  Based upon the SECP, sample preparations of SECPs often involve extensive extraction for complete recovery of the drugs.  In addition, depending upon the size of the SECP and the location of the drug, the SECP may need to be disassembled or reproducibly cut, which can be a significant challenge when the SECP is made from hard plastics or metals.