Prescription drug capsules are invoiced as Class C. Doctors who invoice prescription drug capsules will indicate that they are Class C drugs under the prescription or on the charge invoice, which means that the drugs prescribed by hospitals are not reimbursed by medical insurance and need to be paid at their own expense. Capsule is a kind of preparation in which drugs are wrapped in capsule materials, and it is usually divided into hard capsules and soft capsules. Drugs encapsulated by capsule shell are generally drugs that are irritating to esophagus and gastric mucosa, or drugs that have bad taste and are easy to volatilize. These drugs are packed in capsule shell, which can cover up their own bad smell, protect the drugs from being destroyed and avoid irritating the esophagus and stomach.