Any member of a group of vitamers that belong to the chemical structural class called pantothenic acids that exhibit biological activity against vitamin B5 deficiency. Deficiency of vitamin B5 is rare due to its widespread distribution in whole grain cereals, legumes and meat. Symptoms associated with vitamin B5 deficiency are difficult to asses since they are subtle and resemble those of other B vitamin deficiencies. The vitamers include (R)-pantothenic acid and its ionized and salt forms.