Adherence to (compliance with) drug treatment is important. However, only about half the people who leave a doctor's office with a prescription take the drug as directed. Among the many reasons people give for not adhering to drug treatment, forgetfulness is the most common.
Definition of periodical. 1  1 : periodic 1. 2  2a : published with a fixed interval between the issues or numbersb : published in, characteristic of, or connected with a periodical.
Definition of quarterly. 1  1 : computed for or payable at 3-month intervals a quarterly premium. 2  2 : recurring, issued, or spaced at 3-month intervals. 3  3 : divided into heraldic quarters or compartments.