Pharmacy compounding is when a prescription is custom prepared by a pharmacist. This differs from more common prescription drug distribution in that most prescription drugs are allocated in manufactured dosage forms. Pharmacy compounding requires that the pharmacist begins with a drug in a rawer form, and then treats it in various ways until it is ready for a patient’s use.
Most drugs in a modern pharmacy require little preparation by the pharmacist. They often come in manufactured dosage forms such as tablets, metered dose inhalers, or other preparations that are ready to be used by the patient once distributed. In some rare cases, however, a patient needs a drug that is either not available in a manufactured dosage form or needs the drug in a dosage different from those commonly available. When this happens, pharmacists must use their compounding skills to put the drug in a usable form for the patient.
There are many different ways that pharmacy compounding can be accomplished. A pharmacist may have to crush a tablet and mix it with a transdermal gel for patients that have difficulty swallowing. Active ingredients may have to be measured, mixed, and then encapsulated for patients that need a smaller dosage form or that are allergic to chemicals in the manufactured dosage form. A pharmacist may even be required to mix chemicals and drugs that are not normally distributed together if directed to do so by a physician. All of these actions require great skill and the utmost care, as compounding drugs with the wrong dosages or with incompatible chemicals can result in injury and death.
The results of pharmacy compounding are not limited to humans. Animals often take the same drugs that people do, but in different forms and dosages. A pharmacist may have to compound a smaller dosage of an antibiotic for a cat if directed by a veterinarian, or prepare blood pressure medicine in a transdermal gel for a small dog that refuses to swallow pills.
Pharmacy compounding may seem like a new practice, but it is actually very old. Prior to the 20th century, most pharmacists were required to purify, prepare, distribute, and even extract many of the drugs that they used. This was because medicines were not mass produced like they are today, and often had to be created by the pharmacist from plants and other crude sources. As technology improved and the understanding of how to properly prepare medications increased, mass production techniques were applied to pharmaceuticals. This resulted in the modern pharmacy system, where compounding skills are still necessary but not used as often as they once were.