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Methods For Assesment Of Bioavailability
This document summarizes a seminar presentation on methods for determining bioavailability. It defines bioavailability as the rate and extent to which the active substance of a drug is absorbed and available at the site of action. It then describes the main objectives of bioavailability studies which include aiding new drug and formulation development. The key methods discussed for assessing bioavailability include measuring plasma drug concentration, urinary drug excretion, acute pharmacodynamic effects, clinical observations, and in vitro drug dissolution studies. Specific parameters are defined for each method such as Cmax, AUC, tmax, Du, and Emax. Finally, the document summarizes two literature articles that developed formulations to enhance the oral bioavailability of curcumin and edarav
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Introduction to the seminar on Biopharmaceutics focusing on bioavailability methods by Anindya Jana.
Definition of bioavailability; objectives include drug development, formulation comparison, and absorption efficiency.
Overview of bioavailability assessment methods: plasma concentration, urinary excretion, pharmacodynamic effect, clinical observations, and in-vitro studies.
Details on measuring plasma drug concentration post-administration, emphasizing its indirect method.
Insights into tmax, Cmax, and AUC as crucial metrics for assessing drug bioavailability.
Focus on urinary excretion methods for bioavailability assessment and related metrics like Du and dDu/dt.
Method used when plasma measurement isn't viable; emphasizes establishing dose-response curves for bioavailability.
Clinical observations in trials to determine safety and effectiveness are discussed; the least accurate method.
Importance of in-vitro drug dissolution studies to correlate with in-vivo bioavailability.
Study development on curcumin nanosuspension to enhance oral bioavailability, focusing on a cost-effective method.
In vitro results show significant increase in curcumin bioavailability with nanosuspensions by factors of 3.18 and 3.7.
Research on a novel oral delivery system for edaravone to enhance oral bioavailability, with 571% improvement highlighted.
List of references relevant to bioavailability methods and studies, further informing the research.
A closing slide thanking the audience.
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Methods For Assesment Of Bioavailability
- 1. M.Pharm 2nd SemesterSeminar Subject : Biopharmaceutics Topic : Methods For Determination Of Bioavailability By: Anindya Jana M.Pharm 1st Year (Pharmaceutics) Regd. No. : 1661611006 Date – 18-01-2017
- 2. Bioavailability The rate &extent to which the active substance is absorbed from a drug product & becomes available at the site of action. Objective Of Bioavailability Studies • Primary stages of development of new drug of a suitable dosage form for a new drug entity. • Determination of influence of excipients, patient-related factors and possible interaction with other drugs on the efficiency of absorption. • Development of new formulations of the existing drugs. • Comparison of availability of other drug substance from different dosage forms.
- 3. Methods For AssessingBioavailability 1. Plasma Drug Concentration • Time for the peak plasma (blood) concentration (tmax). • Peak Plasma drug concentration (Cmax). • Area under the plasma drug concentration-time curve (AUC). 2. Urinary Drug Excretion • Cumulative amount of drug excreted in the urine (Du). • Rate of drug excretion in the urine (dDu/dt). • Time for maximum urinary excretion (t). 3. Acute Pharmacodynamic Effect • Maximum Pharmacodynamic Effect (Emax) • Time for maximum pharmacodynamic effect. • Area under the pharmacodynamic effect-time curve. • Onset time for pharmacodynamic effect. 4. Clinical Observations • Well controlled clinical trial. 5. In-Vitro Studies • Drug Dissolution
- 4. Plasma Drug Concentration •Measurement of drug concentration in blood, plasma or serum after drug administration. • Indirect method. • By appropriate blood sampling, an accurate description of the plasma drug concentration-time profile of the therapeutically active drug substances can be obtained.
- 5. I. Time ForThe Peak Plasma (Blood) Concentration (tmax) : It is the time required to reach maximum drug concentration after drug administration. The tmax can be used as an approximate indication of drug excretion rate. II. Peak Plasma Drug Concentration (Cmax) : Represent the maximum plasma drug concentration obtained after oral administration of drug. Cmax provides indications that the drug systemically absorbed to provide a therapeutic response. III. Area Under The Plasma Drug Concentration-Time Curve (AUC) : Is a measurement of extent of drug bioavaibility. The AUC reflects the total amount of active drug that reaches the systemic circulation.
- 6. Urinary Drug ExcretionData • The drug must be excreted in significant quantities as unchanged drug in the urine. • Indirect method. I. Cumulative Amount of Drug Excreted In The Urine (Du) : It is related directly to the total amount of drug absorbed. II. Rate of Drug Excretion In The Urine (dDu/dt) : Rate of drug excretion is dependant on first order elimination rate constant k and the concentration of drug in the plasma Cp. III. Time For Maximum Urinary Excretion (t) : It is analogous to the tmax of plasma level data. Its value decreases as the absorption rate increases.
- 7. Acute Pharmacodynamic Effect •This method is used when the quantitative measurement of drug in plasma or urine lacks an assay with sufficient accuracy and reproducibility. • For locally acting, non systemically absorbed drug products, such as topical corticosteroids, plasma drug concentrations may not reflect the bioavaibility of the drug at the site of action. • The use of acute pharmacodynamic effect to determine bioavailability requires demonstration of dose response curve. • Bioavailability is determined by characterization of dose response curve.
- 8. Clinical Observation • Wellcontrolled clinical trials in humans establish the safety and effectiveness of drug products and may be used to determine the bioavailability. • Clinical approach is the least accurate, least sensitive, and least reproducible. • This approach may be considered acceptable only when analytical methods can not be developed to permit use of one or other approaches.
- 9. In-Vitro Studies • Thebest way of assessing therapeutic efficacy of drug with a slow dissolution rate is in vivo determination of bioavaibility which is usually done whenever a new formulation is to be introduced into the market. • Drug dissolution studies may under certain conditions give an indication to drug bioavaibility. • The in vitro drug dissolution rate should correlate with in-vivo drug bioavaibility. • Dissolution test often performed on several test formulations of the same drug.
- 10. Literature Articles 1. LeiLi et. al. has developed Curcumin (CUR) nanosuspension to enhance CUR oral bioavailability using a cost effective method different from conventional techniques. • Curcumin (CUR), a Biopharmaceutics Classification System (BCS) class IV substance, is a promising drug candidate in view of its good bioactivity. • Nanosuspension is one of the most promising strategies to improve the oral bioavailability of insoluble drugs.
- 11. Result In vitro dissolutiondegree of the prepared CUR nanosuspensions using TPGS or Brij78 as stabilizer was greatly increased. Pharmacokinetic studies demonstrated that the oral bioavailability of CUR was increased 3.18 and 3.7 times after administration of CUR/TPGS nanosuspensions or CUR/Brij78 nanosuspensions, when compared with the administration of CUR suspension.
- 12. 2. Sanjay Garget. al. has developed a Novel Oral Delivery System (NODS) of Edaravone (EDR) to enhance oral bioavailability. • Edaravone (EDR), a strong free radical scavenger, is known for its promising therapeutic potential in oxidative stress (OS) associated diseases. • Poor oral bioavailability is the major obstacle in its potential use. • Oral liquid dosage form is the most preferred delivery method in paediatric, geriatric and specialised therapies. Result Drug release from NODS was slow, sustained and significantly better as compared to suspension. The significant reduction in metabolism and improvement in permeability across the small intestine were observed with NODS compared to free EDR. The oral pharmacokinetic study showed 571% relative bioavailability with NODS compared to EDR suspension. From the results obtained, NODS is a promising candidate for use in OS associated diseases.
- 13. References 1. Shargel L,Pong S, Yu A; Bioavaibility & Bioequivalence; Applied Biopharmaceutics & Pharmacokinetics; Published By Mc Graw Hill; 2005; P 460-464 2. Brahmankar M. D, Jaiswal B. S; Bioavaibility & Bioequivalence; Biopharmaceutics & Pharmacokinetics A Treasure; Published By Vallabh Prakashan; 2010; P 319-326 3. Yutong Wang, Changyuan Wang, Jing Zhao, Yanfang Ding, Lei Li; A cost-effective method to prepare curcumin nanosuspensions with enhanced oral bioavailability; Journal of Colloid and Interface Science; Vol 485; 2017; P 91-98 4. Ankit Parikh, Krishna Kathawala, Chun Chuan Tan, Sanjay Garg, Xin-Fu Zhou; Development of a novel oral delivery system of edaravone for enhancing bioavailability; International Journal of Pharmaceutics; Vol 515; 2016; P 490-499
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