Introduction
Mechanisms of protein drug binding
Kinetics of protein drug binding
Classes of protein drug binding.
1. Binding of drug to blood components.
(a) Plasma proteins
(b) Blood cells
2. Binding of drug to extravascular tissue protein
Determination of Protein-drug Binding
Factors affecting protein drug binding
Significance of protein/tissue binding of drug
The phenomena of complex formation with protein is called as protein binding of drugs.
Binding of drugs fall into two categories mainly :
1. binding of drugs to blood components like – plasma protein and blood cells
2.Binding of drugs to extracellular tissues proteins, fats,bones etc.
The phenomenon of complex formation of drug with protein is called as Protein drug binding. The proteins are particularly responsible for such an interaction. A drug can interact with several tissue components.
Introduction
Mechanisms of protein drug binding
Kinetics of protein drug binding
Classes of protein drug binding.
1. Binding of drug to blood components.
(a) Plasma proteins
(b) Blood cells
2. Binding of drug to extravascular tissue protein
Determination of Protein-drug Binding
Factors affecting protein drug binding
Significance of protein/tissue binding of drug
The phenomena of complex formation with protein is called as protein binding of drugs.
Binding of drugs fall into two categories mainly :
1. binding of drugs to blood components like – plasma protein and blood cells
2.Binding of drugs to extracellular tissues proteins, fats,bones etc.
The phenomenon of complex formation of drug with protein is called as Protein drug binding. The proteins are particularly responsible for such an interaction. A drug can interact with several tissue components.
Physico-chemical Properties in Relation of Drug actionPradnya Gondane
This is the presentation for B. Pharm. IV semester students. It includes all the physico-chemical properties which affect drug action like solubility, ionization, pH, pKa, Protein Binding, Chelation, Hydrogen Bonding, Partition Coefficient and steric factors which includes, optical, conformational and bio isosters. This is prepared according to the PCI syllabus for B. Pharm. IV Semester students for Subject Medicinal Chemistry-I
DRUG INTERACTIONS (MECHANISMS OF DRUG-DRUG INTERACTIONS)N Anusha
A Drug interaction is an interaction between a drug and some other substance, such as another drug or a certain type of food, which leads to interaction that could manifest as an increase or decrease in the effectiveness or an adverse reaction or a totally new side effect that is not seen with either drug alone that can be severe enough to alter the clinical outcome.
Every time a drug is administered with any other prescription medicine, OTC products, herbs or even food we expose ourselves to the risk of a potentially dangerous interaction.
Biopharmaceutics: Mechanisms of Drug AbsorptionSURYAKANTVERMA2
Biopharmaceutics is defined as the study of factors influencing the rate and amount of drug that reaches the systemic circulation and the use of this information to optimise the therapeutic efficacy of the drug products.
The slides describe concept of distribution, Volume of distribution, factors affecting volume of distribution and the barriers to distribution. Blood brain barrier and placental barrier.
High variability in PK can be a characteristic of certain drug products which require different from ordinary strategies and study designs for establishing bioequivalence.
Physico-chemical Properties in Relation of Drug actionPradnya Gondane
This is the presentation for B. Pharm. IV semester students. It includes all the physico-chemical properties which affect drug action like solubility, ionization, pH, pKa, Protein Binding, Chelation, Hydrogen Bonding, Partition Coefficient and steric factors which includes, optical, conformational and bio isosters. This is prepared according to the PCI syllabus for B. Pharm. IV Semester students for Subject Medicinal Chemistry-I
DRUG INTERACTIONS (MECHANISMS OF DRUG-DRUG INTERACTIONS)N Anusha
A Drug interaction is an interaction between a drug and some other substance, such as another drug or a certain type of food, which leads to interaction that could manifest as an increase or decrease in the effectiveness or an adverse reaction or a totally new side effect that is not seen with either drug alone that can be severe enough to alter the clinical outcome.
Every time a drug is administered with any other prescription medicine, OTC products, herbs or even food we expose ourselves to the risk of a potentially dangerous interaction.
Biopharmaceutics: Mechanisms of Drug AbsorptionSURYAKANTVERMA2
Biopharmaceutics is defined as the study of factors influencing the rate and amount of drug that reaches the systemic circulation and the use of this information to optimise the therapeutic efficacy of the drug products.
The slides describe concept of distribution, Volume of distribution, factors affecting volume of distribution and the barriers to distribution. Blood brain barrier and placental barrier.
High variability in PK can be a characteristic of certain drug products which require different from ordinary strategies and study designs for establishing bioequivalence.
Protein Binding of Drugs by Dr. Sanaullah AslamSanaullah Aslam
Your Feedback will be highly appreciated regarding "Protein Binding by Dr. Sanaullah Aslam". In this presentation protein binding of drugs is discussed in such a way that it could be easily understood by students of healthcare system.
High variability in PK can be a characteristic of certain drug products which require different from ordinary strategies and study designs for establishing bioequivalence.
Good Regulators of Pharmaceuticals (GRP) 22 October 2014Ajaz Hussain
Sharing thoughts on what makes a Good Regulator of Pharmaceuticals with pharmacy students at the Universities of Minnesota and Iowa. A point of emphasis on "we all are regulators" is explained and three areas for learning - (a) Systems and Integrative Thinking, (b) Argumentation and (c) Behavioral Economics described.
I hope you, the viewers, will also find some value in reviewing these slides. If you are a student and have some questions please feel free to drop me a email (a2zpharmsci@msn.com).
Educating the Next Generation Pharmacist for Industry. The Panjab University ...Ajaz Hussain
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How have these ideas/concepts introduced into practice?
How can we improve?
Visioning the Next Decade: NIPTE-FDA CollaborationAjaz Hussain
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Sharing my learning in dealing with complexity and uncertainty and shed some light on:
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introduction
mechanisms of protein drug binding
binding of drugs
binding of drugs to blood components
determination of protein drug binding
factors affecting
significance
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Learning objectives:
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3. Describe the components of a normal electrocardiogram of a typical bipolar leads (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
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2. Chapter 9, Human Physiology - From Cells to Systems, Lauralee Sherwood, 9th edition
3. Chapter 29, Ganong’s Review of Medical Physiology, 26th edition
4. Electrocardiogram, StatPearls - https://www.ncbi.nlm.nih.gov/books/NBK549803/
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6. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
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Title: Sense of Taste
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
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Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
- Video recording of this lecture in English language: https://youtu.be/lK81BzxMqdo
- Video recording of this lecture in Arabic language: https://youtu.be/Ve4P0COk9OI
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These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
1. Enlist the non-respiratory functions of the respiratory tract
2. Briefly explain how these functions are carried out
3. Discuss the significance of dead space
4. Differentiate between minute ventilation and alveolar ventilation
5. Describe the cough and sneeze reflexes
Study Resources:
1. Chapter 39, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 34, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 17, Human Physiology by Lauralee Sherwood, 9th edition
4. Non-respiratory functions of the lungs https://academic.oup.com/bjaed/article/13/3/98/278874
2. Drug-Protein Binding
• Drug protein binding is usually a reversible interaction of
drugs with proteins in plasma
• Also includes the reversible interaction of drugs with red
blood cell and tissue membranes and other blood
constituents
• Binding plasma proteins are:
– Albumin
– α1-acid glycoprotein
– Lipoproteins
• PB can be measured in vitro by ultrafiltration &
equilibrium dialysis
3. D-R Effect
D + P D-P
Ka
Kd
+
R
K2 K1
Central
Compartment
Peripheral
Compartment
4. Higher the Kd, the more the unbound drug; lower the K2 the
more effect of the drug
5. Why is PB Important?
• Important from Biological (PK/PD/Toxicology) point of view not from
Clinical point of view
• PK
– High PB will lead to more drug present in the central blood compartment and
therefore a lower Vd
• Exception: high degree of binding to tissue proteins will also show high Vd
– Low PB: more drug is free to move into tissue and therefore result in a high Vd
– Knowledge of the unbound fraction in blood is essential to the correlation of total
plasma concentration with activity
• Toxicity/PD
– High PB of a compound can show drug toxicity
– A small change (from drug interactions or disease state) in the extent of binding of a
very high PB → large change in drug concentration in plasma
• e.g., phenytoin is 90% PB, can be displaced by co prescribed drugs, e.g., valproic
acid, in particular can increase phenytoin Fu by 30% - 100% → lead to toxicity
6. Different Binding Sites
• Albumin and α1-acid glycoprotein have structurally selective binding sites
for drugs
– Each albumin molecule has at least 6 distinct binding sites for drugs and
endogenous compounds
– 2 of these very tightly and specifically bind long chain fatty acids
– Another site selectively binds bilirubin
– Two major sites (site I and site II) mainly bind acidic drugs
• Site I binds drugs e.g., warfarin and phenylbutazone, whereas site II binds drugs
e.g., diazepam and ibuprofen
– Drugs which bind at the same site can be predicted to displace each other
competitively when co-administered
• α1-acid glycoprotein is an acute phase reactant which has one binding site
selective for basic drugs such as disopyramide and lignocaine.
7. Unbound Fraction
• Unbound fraction (Fu)of a drug is determined by:
– the affinity of the drug for the protein
– the concentration of the binding protein
– the concentration of drug relative to that of the binding protein
• In most cases, drug concentrations at therapeutic doses are well below
those of the binding protein and the Fu is constant across the
therapeutic range of drug concentration
• However, the concentration of α1-acid glycoprotein is relatively low, and
saturation of the binding sites can occur in the therapeutic range
– E.g., disopyramide; Cu increases linearly with dose, but there is a less than
proportionate increase in Ct as saturation occurs causing fraction unbound to
increase
• Albumin concentrations are high, and saturation rarely occurs with drugs
binding to this protein
– An exception is salicylate which has high therapeutic concentrations.
8. Effect of Diseases on Protein Conc.
• The concentration of albumin is decreased in liver disease and
renal disease resulting in decreased drug binding
• α1-acid glycoprotein is an acute phase reactant and concentrations
increase in rheumatoid arthritis and post-myocardial infarction
resulting in increased drug binding in these situations
• The binding affinity can be changed due to competition from
endogenous compounds such as fatty acids, or from other drugs
competing for the same protein binding sites
• In-vitro situations
– warfarin is about 98% bound and 2% unbound (Fu = 0.02). If a competing drug
reduces the binding from 98% to 96%, the in vitro Fu rises from 0.02 to 0.04, a
twofold increase
Birkett D. (1992) Australian Prescriber, 15: 56-57
9. In Vivo change in Fu
• In vivo, two compensating mechanisms operate
• Vd is dependent on the ratio of fraction unbound in blood and
tissues (Fu/Fut)
– If Fu in blood increases (competitive displacement) without a change
in tissue binding, Vd increases as the displaced drug ‘spreads out’
and is bound in the tissues. This happens quickly within minutes to
hours
– Secondly, Fu is a factor in the clearance of total drug (clearance =
fraction unbound X intrinsic clearance), but clearance of unbound
drug is determined only by intrinsic clearance and does not depend
on protein binding
– Therefore, when Fu increases due to displacement, drug is
eliminated more rapidly until the unbound (active) steady state
concentration returns to the starting point
– Resulting in an increase in Fu, a decrease in total drug concentration,
but no change in the steady state Cu
10. In Vivo change in Fu
• Ct at steady state is reduced in proportion to the increase in Fu (this takes
3-5 half-lives to occur)
• In general, the only situation where unbound drug concentration at
steady state is dependent on the degree of protein binding is that of
high hepatic clearance drugs given intravenously (e.g. lignocaine)
• In cases like phenytoin, binding to albumin is reduced in renal failure,
liver disease or in the presence of competing drugs
– In such cases, total concentration measurements are misleading and control
of therapy needs to be based on measurement of unbound phenytoin
concentration
– Such measurements are available in specialized centres
16. Clinical Implications
• In nearly all cases where a clinically important protein
binding interaction has been postulated, other mechanisms,
such as concurrent inhibition of drug metabolism, have been
shown to be the in vivo cause of the increase in drug effect
• This is why it is so important in studies of drug interactions to
measure both total and unbound drug in determining the
mechanism(s)
• Except in very rare circumstances, protein binding
displacement in vivo does not result in increased drug effect
21. Lipophilicity
• Lipophilicity is perhaps the most important physical property
of a drug in relation to its absorption, distribution, potency,
and elimination
• Lipophilicity is often an important factor in all of the
following, which include both biological and physicochemical
properties:
22. Good Absorption and Permeation
• There are various guidelines to help, the most well-known of
which is the Lipinski Rule of Five
molecular weight < 500
logP < 5
< 5 H-bond donors (sum of NH and OH)
< 10 H-bond acceptors (sum of N and O)
• An additional rule was proposed by Veber
< 10 rotatable bonds
• Otherwise absorption and bioavailability are likely to be poor.
NB This is for oral drugs only.