As the questioner points out, there are benefits to dosing drugs with consideration of the normal and cyclical rhythms of human physiology. Examples where disease conditions show cyclical patterns that correlate with circadian rhythms include:

Epilepsy: Seizures may occur only at particular times of the day or night

Allergies: Symptoms of sneezing and stuffy nose are typically worse in the morning waking hours

Asthma: Symptoms are more likely to occur in the hours prior to awakening

Rheumatoid arthritis: Pain is often most intense upon awakening.

Osteoarthritis: Symptoms typically worsen in the afternoon and evening.

Angina: Symptoms are most common during the first several after awakening.

Heart attack: Occur most commonly occurs in the early waking hours

Stroke: Most commonly occur in the early waking hours

Diabetes: Insulin levels and the counterregulatory hormones that work against the actions of insulin are in turn, influenced by the circadian rhythm.

Chronotropic drug therapy has been in the physician’s bag of treatments for decades. “Alternate day therapy” has been an option for administration of corticosteroids (e.g., prednisone) for treatment of asthma, rheumatoid arthritis, or other indicated diseases. In this practice, the dose is administered in the early morning every other day. The benefit is to minimize supression of adrenal function and the associated adverse events found in long-term therapy of corticosteroids.

Currently, there are a number of commercially available oral drug-delivery platforms targeted for chronotropic therapy. Applications include delayed-release oral technologies that are administered in the evening and delay the release of antihypertensive drugs until the early morning hours when there are normal increases in heart rate and blood pressure. In addition to oral platforms, parenteral chronotropic systems are experiencing increased utilization. The most widespread application is that of the insulin pump, which is used to administer insulin for the treatment of diabetes mellitus. With the insulin pump, patients can customize insulin delivery to meet their particular requirements. Newer applications of chronotherapy are being reported. For example, time-scheduled regimens for cytotoxic drug delivery by intravenous infusion based on a pharmacokinetic–pharmacodynamic model have been reported.

Historically, the study of circadian rhythms and related treatments in medical schools has been limited. With increased knowledge of the physiological basis, therapeutic benefits of chronotherapy, and advances in drug-delivery technologies, we can expect to see increased application of drug-delivery technologies to chronotherapy.