Title 2.3 DETERMINATION OF DOSE AND DOSING INTERVAL.pdf ✅

K.P. ARUN LECTURER DEPARTMENT OF PHARMACY PRACTICE JSS COLLEGE OF PHARMACY OOTY
INTRODUCTION The dose of a drug is the amount at the time of administration to obtain a desired therapeutic response Dosage regimen refers to the schedule of dosing Generally, the manufacturers provides a range of doses for a given drug Since, several factors affecting the dose of a drug, the exact amount of a drug to be administered is decided by the health care professionals The dose of a given drug is specific to the patient Thus, a fixed dose of a drug might be an overdose in some patients, whereas the same dose might be considered an under-dose in another group of patients The inter and intra subject variations to the effects of drugs can be avoided by tailoring a dose (or a dosage regimen) to a given patient through the use of clinical pharmacokinetics
INTRODUCTION... Some of the factors affecting the dose of a drug include Pharmaceutical factors  Type of dosage form  Route of administration Patient related factors  Individual patient’s tolerance of the drug  Genetic predisposition  Concurrent administration of other drugs  Patient’s age, body weight, gender  Length of illness  General physical health  Liver and kidney function in the patient Pharmacokinetic factors  Rate and extent of  Absorption  Distribution  Metabolism and  Excretion of drugs in patients
INTRODUCTION... For an optimal therapeutic response, we must select a suitable drug and determine an appropriate dose with the available strengths and a convenient dosing interval To meet this responsibility, the serum or plasma drug concentrations have to be analyzed, pharmacokinetic parameters have to be evaluated, the drug dose has to be adjusted and the dosing interval has to be determined Pharmacokinetic-Based Design and Modification of Dosage Regimens: Traditionally, drug information provided by pharmaceutical companies (such as package inserts and Physicians’ Desk Reference) has contained information about the pharmacokinetics of drugs and the therapeutic range (if available) Depending on this information, the focus of design of dosage regimens has been the use of pharmacokinetic data
Pharmacokinetic-Based Design and Modification of Dosage Regimens... IV Bolus Dosing: STEP – 1: Estimation of a target average steady state concentration(Cave ∞): The following equation defines Cave ∞ the value based on the minimum (Cmin ∞) and maximum (Cmax ∞) steady state concentrations equal to MEC and MTC, respectively We should note that the Cave ∞ is slightly different from an algebraic average of Cmin ∞ and Cmax ∞ Cave ∞ = Cmax ∞ - Cmin ∞ / ln (Cmax ∞ /Cmin ∞ )