Final answer:
The major online drug databases for HSOP students are DrugBank, PubMed, PubChem, and ClinicalTrials.gov, which provide information on drugs, chemical molecules, life sciences topics, and clinical studies.
Step-by-step explanation:
The four major drug databases available online to HSOP students are DrugBank, PubMed, PubChem, and ClinicalTrials.gov. DrugBank is a comprehensive resource that provides detailed drug and drug target information. PubMed is a free search engine accessing primarily the MEDLINE database of references and abstracts on life sciences and biomedical topics. PubChem is a database of chemical molecules and their activities against biological assays. ClinicalTrials.gov is a database of privately and publicly funded clinical studies conducted around the world.