Allegra is a blockbuster allergy medication that generated over $1.8 billion in global sales in 2004. Allegra, or Fexofenadine, decreases allergy symptoms by inhibiting the action of histamines. Histamines are naturally occurring molecules that are released from some cells when a person is exposed to pollen or other allergens. When histamine is released in nasal cells, the classic runny nose can occur. Because Fexofenadine is unable to cross the blood brain barrier, it is able to relieve allergy symptoms without causing the extreme drowsiness seen with earlier antihistamine drugs.

The structure of Fexofenadine is shown below.

More on Chemical Structure Abbreviations+ open

(A) Enter the formula for Fexofenadine by typing the number of each atom in the blanks. If Fexofenadine does not contain any atoms of that element, enter "0";

Number of Carbon atoms
unanswered
Number of Hydrogen atoms
unanswered
Number of Nitrogen atoms
unanswered
Number of Oxygen atoms
unanswered
Number of Phosphorus atoms
unanswered
Number of Sulfur atoms
unanswered