factors include abnormal esophageal anatomy and/or motility, the size of the tablet or capsule, the pH of the drug in solution, and the intrinsic irritability of the drug. It is noteworthy that doxycycline capsules are fairly large and that the pH of a I percent solution of doxycycline ranges from 2.7-3.0.'·3 Clinical pharmacists, dispensing pharmacists, and physicians should be aware of the problems associated with these drugs and the potential problems that may exist with any solid oral dosage form. When dispensing oral tetracyclines, pharmacists should advise patients to take their medication with an adequate quantity of water and not to take it within one hour of retiring.