Final answer:
Without a 'Med guide' that includes safe usage instructions, a prescription is considered incomplete. This guide is essential to help prevent drug abuse and to comply with drug advertising regulations.
Step-by-step explanation:
A 'Med guide' written in lay language that must be provided with a prescription includes explanations on the safe use of a medication. Without it, the prescription is considered incomplete. The provision of this 'Med guide' is crucial as it helps prevent drug abuse, which is the use of a drug without the advice of a medical professional and for reasons not originally intended. Moreover, drug advertising regulation mandates that a company can only promote a drug for the specific indication or medical use approved by the FDA, and an advertisement must maintain a "fair balance" between the benefits and the risks of the drug. Usage of a drug for non-approved conditions, known as off-label use, can lead to serious health complications and is subject to Postmarket Safety Surveillance to ensure ongoing monitoring of drug effects after approval.