Regulation for the radiopharmaceuticals should be reasonably different from that of other drugs. Radiopharmaceuticals are always used by compounding based on the doctor's order, have short half life and very low administration dose. Its pharmacological effect is not from its chemical effect but from radiation. The background for exploratory IND (Investigational New Drug) explained by the FDA was to reduce the time and resources expended on candidate products that are unlikely to suceed, new tools are needed to distinguish earlier in the process those candidates that hold promise from those that do not. In this review, basic concept for exploratory IND and RDRC guideline is summarized and various suggestions for improving and expediting procedure for new radiopharmaceutical development would be described.
Half-Life ; Korea* ; Radiopharmaceuticals

This tutorial defines the principles of the concentration - effect relationship which are the basis of pharmacodynamics. The two key parameters of pharmacodynamics are the maximum response (Emax) and the concentration producing 50% of Emax (C₅₀). The time course of effect is illustrated under the assumption that drug effects are immediately related to concentration in the central compartment e.g. plasma. The related idea of duration of drug action and its relationship to dose is shown to have a simple relationship with drug half-life.
Half-Life ; Plasma

Authors have developed highly reproducible calibration method for the Micro-Selection HDR Ir-192 system(Nucletron, Netherland). The new jig has a 10cm radius circular hole in the 30cm x 30cm x 0.2cm acrylic plate, and 5F flexible bronchial tubes are attached around the hole. The source moves along the circle in the tubes an? the ionization chamber is placed vertically at the center of the circular hole(center of the jig). Dose distribution near the center was derived theoretically, and measured with the film dosimetry system. Theoretical calculation and measurement show the error margin below 0.1% for 1mm or 2mm position deviation. We have measured at 12 and 24 points of circle with 1, 6, 11 and 21 second dwell time of source in order to calculate the activity of the source. Measurements have been repeated daily for 50 days. The accuracy and the reproducibility are below 1% error margin. The half life of the source from our measurement is estimated 73.4+/-0.4 days.
Calibration* ; Film Dosimetry ; Half-Life ; Radius

Pharmacokinetics is the study of the rate and degree of drug transport to various tissues in the human body. Pharmacokinetic parameters summarize drug kinetics and ideally predict a clinical situation. A single kinetic profile may be summarized by peak concentration, peak time, half-life and area under the curve. Dosage regimens are designed to confer the maximum desired effects for the required time period with minimal toxicity. Target-controlled infusions use pharmacokinetic models to titrate intravenous anesthetic administration to achieve a desired drug concentration. Context-sensitive half time is used to predict the clinical time course, rather than terminal half-life. It is important that anesthesiologists understand the basic pharmacological principles and apply them in their daily clinical practice. This review discusses the ways in which anesthesiologists can design a patient-specific dosage regimen of intravenous anesthetics by utilizing basic concepts of pharmacokinetics and pharmacodynamics using pharmacokinetic simulations.
Anesthetics, Intravenous ; Half-Life ; Human Body ; Pharmacokinetics*

The effects of CYP1A enzyme on the pharmacokinetics of p-acetaminophen were studied in Bactrian camel. Twelve Bactrian camels were divided into 2 groups, then given a single dose of p-acetaminophen only or with the enzyme inhibitor lomefloxacin. Blood samples were collected after different intervals, and p-acetaminophen concentration was determined by high-performance liquid chromatography. Pharmacokinetic parameters were analyzed by Phoenix WinNonLin v.7.0. The results show that lomefloxacin can significantly inhibit Bactrian camel CYP1A enzyme, as evidenced by the prolonged elimination half-life, increased maximum plasma concentration and area under the curve values and the shortened time to peak concentration for p-acetaminophenol in the substrate with inhibitor group. The results lay a foundation for revealing the particular characteristics of the CYP1A enzyme in Bactrian camels.
Camels ; Chromatography, Liquid ; Half-Life ; Pharmacokinetics ; Plasma

PURPOSE: The purposes of the authors' analysis were to assess the values that plastic surgery journals demonstrate in terms of the standardized measures created by the Korea Medical Citation Index, and to assess the relationship between these values and the turnaround time of these journals. METHODS: The overall indexes of J Korean Soc Plast Reconstr Surg(JKSPRS), J Korean Soc Aesthetic Plast Surg(JKSAPS), J Korean Cleft Palate-Craniofac Assoc (JKCPRA) were compared with those of journals related with Korean plastic surgery using the following parameters: impact factor, cited half-life, total articles, and the number of journals. Korean plastic surgery journals were compared with journals from relative fields. In addition, an evaluation of all original articles published in 2007, assessing the time intervals from submission to publication was conducted for Korean plastic surgery journals and various journals which were related with plastic surgery. RESULTS: The number of articles for Korean plastic surgery journals for 2006 ranged from 19 for JKCPRA to 149 for JKSPRS. The time interval from submission to publication of an article among Korean plastic surgery journals for 2007 ranged from 73.7 days for JKSAPS to 176.2 days for JKSPRS. The variation in impact factor of JKSPRS for the period from 2002 to 2005 increased from 0.084 in the year 2002 to 0.168 in 2005. But the impact factor in 2006 has fallen to 0.112. CONCLUSION: JKSPRS demonstrated comparatively high overall index values and a short turnaround time in comparison to relative journals. To improve the status of Korean plastic surgery journals, members of Korean plastic surgeons should quate Korean plastic surgery journals and adjust key word to MeSH. The title written down in Korean should use medical terminology published by Korean medical association.
Half-Life ; Korea ; Publications ; Serial Publications ; Surgery, Plastic

This tutorial deals with basic concepts of clearance, the most important parameter in pharmacokinetics but often challenging for students in clinical pharmacology. Its relationships with dose, concentration and elimination rate are discussed using a physical model and examples of commonly used drugs, as well as its physiological aspects pertaining to the blood flow to differing organs. Finally, application of clearance to the calculation of maintenance dose rate and half-life is used to show how it is essential in pharmacotherapy and clinical pharmacology.
Drug Therapy ; Half-Life ; Humans ; Pharmacokinetics ; Pharmacology, Clinical

This tutorial deals with basic concepts of absorption processes and links previous tutorials on clearance and volume of distribution to introduce the concept of half-life. The time course of both absorption and elimination are commonly described using a half-life. Half-life can also be used to describe drug accumulation. Understanding the principles underlying the time course of absorption and elimination are essential in pharmacotherapy and clinical pharmacology.
Absorption* ; Drug Therapy ; Half-Life* ; Pharmacokinetics ; Pharmacology, Clinical

The pharmacokinetics of intravenously adminstrered lidocaine were studied in 5 normal patients withno renal disease and 4 patients with end-stage renal failue during anesthesia. In both group of patinets, the half life, the volume of distribution and clearance were not significantly different. However, valuses were altered in comparison with those of subjuc without anesthesia. This alteration of parameters is thought to be the effect of reduced hepatic blood flow due to potent anestheics grugs. Our understanding of lidocaine pharmacokinetics in patients with chronic renal failure during anesthesia suggests that these patients can safely receive a normal loading and maintenanece dose with close monitoring for signs of lidocaine toxicity. even though the total plasma concentration may be within the therapeutic range.
Anesthesia* ; Half-Life ; Humans ; Kidney Failure, Chronic ; Lidocaine ; Pharmacokinetics ; Plasma

Riboflavine tetrabutyrate is a fat soluble riboflavine derivative. It was synthesized by esterification of riboflavine with fatty acid chloride or by esterification of riboflavine with fatty acid anbydride. The advantage of riboflavine tetrabutyrate is prolongation of its biologic half life and as a result enhancing effectivity of riboflavine, This riboflavine tetrabutyrate has been used for treatment of various dermatoses of which Pathogenesis are believed to be related with abnorma1 Iipid rnetabolism. Receatty, there were many case reports showing markedly improved clinical synptoms ofpsoriatic patients who had been administered oral riboflavine tetrabutyrate for more than one month in Japan. In this clinical trial, we have also experienced effectiveness in 4 of 7 psoriatic pztients who was given oral riboflavine t trabutyrate for more than 3 months.
Esterification ; Half-Life ; Humans ; Japan ; Psoriasis* ; Riboflavin* ; Skin Diseases