Abstract
Background: Chronopharmacology is the science dealing with the optimization of drug effects and minimization of adverse effects by timing the medications in relation to the biological rhythm. Blood pressure (BP) in normotensive person raises in the early morning, gradually dips by noon, and peaks again by evening to show a greater fall during midnight . To maintain a steady Blood pressure throughout the day necessitates to have knowledge of chronopharmacology and drugs following it.

Aims and Objectives: The aim of this study is to evaluate the relevance of drug administration to patients with the standard chronopharmacological guidelines.

Materials and Methods: Data were obtained from clinical case records of patients admitted in wards of Department of Medicine at K.V.G Medical College Hospital, Sullia, from December 2014 to June 2016 based on inclusion and exclusion criteria.

Results: The study involved a total 744 subjects of either gender, of which 68.10 % (n = 506) were males and 31.98% (n = 238) were females with their average age being 55.97 and 55.96 years, respectively. Chronopharmacological relevance was found with 28 drugs, of all antihypertensives were 25 including diuretics, i.e., 17 antihypertensives and 7 diuretics. Nifedipine, a calcium channel blocker to be administered in the morning, all of the 100% of subjects received the drug in the morning with excellent relevance to chronopharmacology. Amlodipine to be administered ideally in the morning was seen to be followed in 98% of subjects, while a fixed drug combination (FDC) of amlodipine and olmesartan (10 mg/40 mg) to be taken at night showed 100% correlation for chronopharmacology . Enalapril, an angiotensin-converting enzyme inhibitor,was given to 10 patients, of which 80% of patients received them at bedtime and followed appropriate chonopharmacology for the drug. Telmisartan, an angiotensin receptor blocker, has shown only 30% relevance as bedtime administration. Beta blockers such as propranolol and metoprolol showed only 79% and 50% of bedtime and morning relevance, respectively. Diuretics are ideally prescribed in the morning. FDC of furosemide with amiloride (40 mg/5 mg) and furosemide with spironolactone (20 mg/50 mg) have followed the chronopharmacology in 100% of subjects. Furosemide alone was administered in the morning in only 60% of subjects.

Conclusion: A very few antihypertensive and all of the diuretics have shown chronopharmacological relevance with their time of administration. A few like telmisartan and other FDC of diuretics have shown poor relevance to chronopharmacology. This could be because of the lack of knowledge of chronopharmacology and circadian rhythm. In conclusion, the timing of drug administration is in good relevance to standard chronopharmacology. This study has provoked the need for updating the knowledge of chronopharmacology and its application in clinical practice for a better patient recovery and good quality of life.

Key words: Chronopharmacology; Antihypertensive; Diuretics, Fixed Drug Combinations; Chrono Therapeutics; Angiotensin-converting Enzyme Inhibitor; Angiotensin Receptor Blockers