: Mechanism of action, drug-receptor interactions, and dose-response curves.

: The World Health Organization provides the WHO Model Formulary as a free PDF, which is the gold standard for essential medicines and their pharmacological use.

For students and professionals looking for free, legal downloads:

: Antibiotics, antifungals, and antivirals.

: Offers peer-reviewed, open-license textbooks like " Clinical Pharmacology " that can be downloaded in PDF, EPUB, and Kindle formats for free. Academic & Research Databases