Pro re nata

Pro re nata is a Latin phrase meaning "in the circumstances" or "as the circumstance arises". It is commonly used in medicine to mean "as needed" or "as the situation arises." It is generally abbreviated to p.r.n. in reference to dosage of prescribed medication that is not scheduled; instead administration is left to the nurse/caregiver or the patient's prerogative. Such administration of medication is not meant to imply, and should never allow for, exceeding a given daily dosage.

The term "p.r.n. adaptor" may also be used to refer to the Luer lock adapter placed on a catheter (cannula) to allow administration of injections. Other terms for this medical device are "injection port" and "saline lock."^{[citation needed]}

Common PRN medications

Most often, these medications are analgesics such as paracetamol, also known as acetaminophen, hydrocodone (Vicodin), laxatives such as docusate, anti-anxiety medicines such as lorazepam (Ativan), hypnotics such as eszopiclone (Lunesta) and antiemetics such as ondansetron or dimenhydrinate (Gravol).^{[citation needed]}

None of the medications above are considered maintenance therapy. p.r.n. is often added to the prescribed directions for medication used to treat symptoms (as above: pain/fever, constipation, insomnia, anxiety, nausea/vomiting), but generally never as a maintenance drug.

Pro re nata is often used for blood tests. A physician will write the order for blood work with p.r.n. added to it. The patient may then use that order when needed.

The initials p.r.n. also refer to casual employment, or "as needed". The usage of the initials started in the medical profession and were soon used in other industries.

External links

• Definition of PRN from Merriam-Webster Medical Dictionary online