Better prescription assistance can be provided by applying basic pharmaceutical science concepts, and by considering evidence from clinical trials. For example, several drugs are currently used to treat ulcerative colitis (UC), a form of inflammatory bowel disease. In general, after a drug is administered, it is first absorbed into the upper part of the small intestine and then enters the bloodstream. However, 5-aminosalicylic acid (5-ASA), which is commonly used to treat UC, acts locally on the colonic mucosa; its absorption must be prevented in the upper gastrointestinal tract so that it can be delivered to the colorectal mucosa. Therefore, in this case, it is important to consider drug dissolution tests rather than pharmacokinetics. Currently, three types of 5-ASA formulations are available: a pH-dependent release formulation, a time-dependent release formulation, and a combination of the two at maximum dosages of 3600, 4000, and 4800 mg, respectively. Although it is often thought that selecting a high dose is better, the clinical effectiveness of 5-ASA is determined by the amount of drug actually delivered to the lesion. Therefore, rather than dosage, it is most important to understand differences in drug solubility. It is beneficial to provide prescription assistance for the treatment of UC by 5-ASA, because when 5-ASA fails, a steroid or expensive biological drug is administered. We will present a case study and discuss the future of prescription assistance using Academic Detailing.