A theophylline dosage regimen which reduces round-the-clock variations in plasma concentrations resulting from diurnal pharmacokinetic variation

Chronopharmacology in Therapeutic Drug Monitoring-Dependencies between the Rhythmics of Pharmacokinetic Processes and Drug Concentration in Blood

The objective of the optimization of pharmacotherapy compliant with the basic rules of clinical pharmacology is its maximum individualization, ensuring paramount effectiveness and security of the patient's therapy. Thus, multiple factors that are decisive in terms of uniqueness of treatment of the given patient must be taken into consideration, including, but not limited to, the patient's age, sex, concomitant diseases, special physiological conditions (e.g., pregnancy, lactation, extreme age groups), polypharmacotherapy and polypragmasia (particularly related to increased risk of drug interactions), and patient's phenotypic response to the administered drug with possible genotyping. Conducting therapy while monitoring the concentration of certain drugs in blood (Therapeutic Drug Monitoring; TDM procedure) is also one of the factors enabling treatment individualization. Furthermore, another material, and yet still a marginalized pharmacotherapeutic factor, is chronopharmacology, which indirectly determines the values of drug concentrations evaluated in the TDM procedure. This paper is a brief overview of chronopharmacology, especially chronopharmacokinetics, and its connection with the clinical interpretation of the meaning of the drug concentrations determined in the TDM procedure.

Chronopharmacology of furosemide in the elderly

The authors have previously reported the time-dependent change in the diuretic effects of furosemide, a loop diuretic agent, in young and middle-aged subjects. The current study was undertaken to examine an influence of aging on this chronopharmacologic phenomenon. Ten milligrams furosemide was given intravenously to 12 elderly subjects (greater than 70 years of age) at 9:00 AM (day trial) or at 9:00 PM (night trial) by a cross-over design. One-hour urine samples were collected for 3 hours after each administration, and urine volume and urinary excretions of sodium and furosemide were determined. Urine volume and urinary sodium excretion increased after furosemide administration. Contrary to the findings in the young and middle-aged subjects, no significant differences were observed in these parameters at any observation period between the day and night trials in the elderly subjects. Urinary furosemide excretion of the day and night trials did not significantly differ. These results suggest that the chronopharmacologic profiles of furosemide are altered in the elderly.

Chronotherapy of trichlormethiazide in hypertensive patients

Circadian influence of trichlormethiazide on serum electrolyte levels, lipid levels, and glucose levels were evaluated in 12 hypertensive patients. One tablet of trichlormethiazide (2 mg) was given once a day at 7:00 AM or 7:00 PM for 8 weeks. The study was done by a crossover design. Twenty-four-hour urine was collected, and fasting blood samples were obtained during the control period and at the end of each treatment period. The 24-hour urine level increased slightly after treatment with trichlormethiazide in the morning and evening trials. Urinary excretion of sodium also increased slightly in the morning trial and increased significantly in the evening trial. Serum concentrations of potassium and chloride decreased, and serum uric acid level increased after trichlor-methiazide treatment. No significant difference was observed in these parameters between morning and evening trials. Fasting blood glucose levels increased after trichlormethiazide treatment. The increment in blood glucose levels was greater in the evening trial than in the morning trial. These data indicate that the influence of trichlormethiazide on glucose tolerance might vary with its administration time.

Circadian influence on effect of propranolol on exercise-induced tachycardia in healthy subjects

Following a cross-over design propranolol 20 mg p.o. was given to 7 healthy subjects at 09.00 h and 21.00 h at an interval of 1 week. Heart rate (HR) during submaximal ergometer exercise was measured at four intervals during 10 h after treatment. Plasma propranolol concentrations were also determined. The suppressive effect (%R) of propranolol on the rise in HR during exercise after the morning dosage was significantly greater at 1.5 h and tended to be greater 3 h after administration than at comparable times in the evening trial. Mean plasma propranolol concentrations during the early phase were higher after the morning than the evening dose. The maximum plasma concentration (Cmax), area under the plasma concentration-time curve from 0 to 10 h (AUC (0-10] and absorption rate constant (ka) were significantly greater after the morning dose. The time to maximum concentration (tmax) and elimination half-life (t 1/2) of the morning and evening dosages did not differ. A significant correlation was observed between plasma propranolol concentration and %R in HR during exercise in the morning (r = 0.74) and evening (r = 0.63) trials, and the regression lines of the morning and evening treatments did not differ.(ABSTRACT TRUNCATED AT 250 WORDS)

Chronopharmacological study of nitrendipine in healthy subjects

Nitrendipine 20 mg or placebo was given orally to eight healthy subjects in a cross-over design separated by 1 or 2 weeks. Drug was given at 9:00 AM (morning dosage) or at 9:00 PM (evening dosage). Systolic and diastolic blood pressure (SBP, DBP) were measured just before and 1, 2, 3, 4, 5, 7, 9, 12 and 24 hrs after treatment. Plasma nitrendipine concentrations were determined at 0.5, 1, 2, 3, 4, 5, 7, 9, 12 and 24 hrs and plasma catecholamines were measured at 2 and 5 hrs following drug administration. SBP did not decrease significantly after nitrendipine compared to after placebo at 9:00 AM or at 9:00 PM. DBP decreased significantly at 2, 3, 4 and 5 hrs after nitrendipine at 9:00 AM, but only at 4 hours after the 9:00 PM dose. Mean plasma nitrendipine concentrations during the absorption phase were lower after the evening dosage compared to the morning interval. Maximum plasma concentration (Cmax) was significantly lower and time to maximum concentration (tmax) tended to be longer after the evening dosage. Area under the plasma concentration-time curve from 0 to 24 hours (AUC0-24) and half-life of the terminal elimination phase (t1/2 beta) of the morning and evening dosages did not differ. A significant correlation was observed between plasma nitrendipine concentrations and changes in DBP during the drug treatment. Plasma noradrenaline concentrations were significantly higher 5 hours after nitrendipine compared to after placebo at 9:00 AM, but not at 9:00 PM.(ABSTRACT TRUNCATED AT 250 WORDS)

Chronopharmacokinetic studies of pranoprofen and procainamide

There is increasing evidence demonstrating that plasma drug concentrations are affected by their time of administration. In the current study, the chronopharmacokinetic profiles of an antipyretic agent, pranoprofen, and an antiarrhythmic agent, procainamide, were examined. In the first study, 75 mg of pranoprofen was given orally in seven healthy subjects at 10:00 (morning trial) or 22:00 (evening trial). In the second study, 500 mg of procainamide was given orally in eight subjects with premature ventricular contractions at 10:00 or 22:00. Blood samples for plasma drug concentrations were taken for a 10-hour (pranoprofen study) or a 24-hour (procainamide study) post-drug period. In the first (pranoprofen) study, the mean time to maximum concentration was significantly shorter, and the mean maximum plasma concentration as well as absorption rate constant had a tendency to be greater after the morning than after the evening trial. The mean area under the plasma concentration-time curve, elimination half-life or oral clearance of the morning and evening dosages did not differ. In the second (procainamide) study, no significant difference was observed in any pharmacokinetic parameter concerning procainamide or its active metabolite, N-acetyl-procainamide (NAPA) between the morning and evening trials. These data indicate that plasma levels of pranoprofen are affected by its administration time while plasma concentrations of procainamide and NAPA do not vary with the time of dosage.