Unit-1 Introduction

Dr Shivaraj D RAssistant Professor & Clinical PharmacistDepartment of Pharmacy PracticeSree Siddaganga College of Pharmacy and SMCRITumakuru2021-2022

Clinical Pharmacokinetics & Pharmacotherapeutic Drug Monitoring

UNIT-1 INTRODUCTION

Pharmacology Study of action of drugs on a living organisms. It explains • When • Where • How & • Why Drugs will act and which body cells are participated in this process.

There are 6 main branches; • Pharmacokinetics • Pharmacodynamics • Pharmacotherapeutic { including Chemotherapy} • Clinical pharmacology • Toxicology • Pharmacometrics

Toxicology Study of poisons and adverse effect of drugs. Ex. Paracetamol poisoning (antidote: Acetyl cysteine)

Pharmacometrics Dealing with identification (screening) & comparative evaluation (qualitative & quantitative) of drugs. Pharmacotherapeutic Uses of drugs in prevention and treatment of disease.

Pharmacokinetics and Pharmacodynamics: • PK deals with ADME of drugs • PD deals with biochemical and physiological effects of drugs & their mechanism of action.

Clinical Pharmacokinetics (CPK): • Pharmacokinetics is defined as the kinetics of drug absorption, distribution, metabolism and excretion (KADME) and their relationship with the pharmacologic, therapeutic or toxicological response in man and animals. • The applications of pharmacokinetic principles in the safe and effective management of individual patient are called as clinical pharmacokinetics. • Pharmacokinetics is also applied to therapeutic drug monitoring (TDM) for very potent drugs such as those with a narrow therapeutic range, in order to optimize efficacy and to prevent any adverse toxicity.

Plasma drug concentration-Time profile

Pharmacodynamic Parameters: Minimum effective concentration (MEC): It is defined as the minimum concentration of drug in plasma required to produce the therapeutic effect. Maximum safe concentration (MSC): Concentration of drug in plasma above which adverse effects are precipitated. Onset of Action: Concentration at which crosses the MEC Onset Time: time required for the drug to start producing pharmacological response.

Duration of Action: The time period for which the plasma concentration of drug remains above the MEC level Therapeutic Range: The drug concentration between MEC and MSC Therapeutic Index: The ratio of MSC to MEC

Pharmacokinetic Parameters: Peak Plasma concentration (Cmax): • The point of maximum concentration of drug in plasma is Called as peak and the concentration of drug at peak is known as Cmax • It is expressed in mcg/ml Time of Peak concentration (tmax): • The time for drug to reach peak concentration in plasma. • It is expressed in hours. Area Under Curve (AUC): It represents the total integrated area under the plasma level-time profile and express the total amount of drug that comes into the systemic circulation after its administration. It is expressed in mcg/ml X hours.

Rate, Rate Constants and Order of Reactions: • The velocity with which a reaction or process occurs is called as its Rate. • The manner in which the concentration of drug influences the rate of reaction is called as the order of reaction or order of process. • The 3 commonly encountered rate process in physiological system are • Zero order process • First order process or Linear kinetics • Mixed order process or Non-linear kinetics

Zero order process: It can be defined as the one whose rate is independent of the concentration of drug undergoing reaction i.e. the rate of reaction cannot be increased further by increasing the concentration of reactants. First order kinetics: The one whose rate is directly proportional to the concentration of drug undergoing reaction i.e. greater the concentration, faster the reaction. Mixed Order kinetics • It is defined as the “Pharmacokinetic parameters change with the size of administered dose. • It is a dose-dependent and it follows combination of 1st order and zero order rate process.

Biological half-life: • It is defined as the time taken for the amount of drug in the body as well as plasma concentration to decline by one-half or 50% its initial value. • It is expressed in hours or minutes. • t1/2 = 0.693/KE Elimination rate constant (Ke) can be defined as the fraction of drug in an animal that is eliminated per unit of time, e.g., fraction/h. Clearance: Clearance is defined as the theoretical volume of body fluid containing from which the drug is completely removed in a given period of time.

Loading dose: A drug does not show therapeutic activity unless it reaches the described steady state. Plateau can be reached immediately by administering a dose that gives the desired steady state. Such an initial dose intended to be therapeutic is called as loading dose. Maintenance dose:it is the maintenance rate [mg/h] of drug administered equal to the rate of elimination at steady state.

Applications of Clinical Pharmacokinetics: • Design and development of new drugs with greatly improved therapeutic effectiveness and no toxic effects. • Design and development of an optimum formulation, for better use of the drug. • Design and development of controlled or targeted-release formulation. • Select the appropriate route for drug administration. • Select the right drug for a particular illness.

Unit-1 Introduction

Unit-1 Introduction

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