Medical abbreviations provide necessary shorthand in healthcare, appearing frequently on prescriptions, patient charts, and discharge instructions. These condensed forms allow for clear, efficient communication among doctors, nurses, and pharmacists. For patients reviewing their own documentation, one of the most frequently encountered abbreviations is “PO.” This simple two-letter code is a direct instruction regarding how a medication must be administered.
Defining PO and Its Latin Origin
The abbreviation PO is derived from the classical Latin phrase per os. This phrase literally translates to “through the mouth.” In a medical context, PO is used exclusively to designate that a drug or substance must be taken orally, meaning the patient is required to swallow it. This designation distinguishes it from all other routes of administration, such as injection, topical application, or administration under the tongue.
Practical Administration of PO Medications
Medications prescribed for the PO route come in many different forms, including solid tablets, hard or soft capsules, liquid solutions, and suspensions. Suspensions contain fine drug particles dispersed in a liquid base and often require shaking before use. Swallowing the medication is the mechanical action required for PO drugs to work. This is typically done with a glass of water to ensure passage down the esophagus.
Specific administration instructions are crucial for the drug’s effectiveness. Some medications are designed as sustained-release or enteric-coated formulations to release the drug slowly or bypass stomach acid. Instructions often prohibit crushing or chewing these specialized tablets, as this action would destroy the coating and cause rapid absorption. Furthermore, some drugs must be taken with food to decrease stomach irritation, while others must be taken on an empty stomach to prevent food from interfering with their uptake.
Why the Oral Route Is Chosen
The oral route is the most common method for drug delivery, primarily due to its non-invasive nature and high patient convenience. Patients can easily self-administer PO medications, making it ideal for managing long-term conditions. PO drugs are also generally the most cost-effective to manufacture and distribute.
Once swallowed, the medication travels down the digestive tract where it is absorbed, mostly through the small intestine, before entering the bloodstream for systemic circulation. This absorption process is relatively slow, meaning the oral route is not suitable when a rapid onset of action is required, such as in an emergency. Furthermore, some drugs cannot be given orally because they would be chemically destroyed by the strong acid and digestive enzymes present in the stomach. In these cases, an alternative route like injection is necessary.