Final answer:
The best course of action would be to re-assess the patient.
Step-by-step explanation:
Based on the scenario provided, the best course of action would be option D: Re-assess patient. The fact that Mr. Richardson is still vomiting and experiencing no relief from pain medication 45 minutes after receiving it suggests that his condition may have worsened or there may be an underlying issue that needs to be addressed. Re-assessing the patient would involve checking vital signs, further examining the symptoms, and considering alternative treatment options if necessary.