Maxwell's principles emphasize the importance of safe, effective, and evidence-based prescribing tailored to the patient's needs. The key principles include:

1. Prescribe drugs based on clinical need: This means drugs should be prescribed only when there is a valid medical indication, ensuring that treatment is justified and necessary.

2. Prescribe drugs after evaluating risks and benefits: The clinician should always weigh the potential therapeutic benefits against possible adverse effects or harms before initiating therapy.

3. Prescribe the minimum effective dose for the appropriate duration: This minimizes potential toxicity, reduces the risk of side effects, and helps prevent issues like antimicrobial resistance.

4. The incorrect option, "Use only patented drugs," is NOT part of these principles. Rational prescribing encourages the use of generic drugs or the most cost-effective options with proven efficacy, rather than being limited to patented (and often more expensive) medications.

Therefore, the correct answer is Option 2: Use only patented drugs because it contradicts the core principle of rational prescribing to choose appropriate, accessible, and cost-effective therapy rather than focusing on patent status.

Reference: *Pharmacology and Therapeutics, Volume 3, Chapter 15, Page 482*