Many compounds have been described by various pharmaceutical companies besides the compounds that led to the discovery of aprepitant. GR-205171 (figure 4) was developed by Glaxo and was based on CP-99994. GR-205171 had a tetrazole ring in position 4 of the benzyl ring of CP-99994 that was intended to increase oral bioavailability and improve pharmacokinetic properties. It was developed up to phase II clinical trials for the treatment of postoperative nausea and vomiting, migraine and motion sickness. It showed good results in emesis, but development was discontinued.