At the end of this e-learning session students will learn:
1. Definition of biotransformation/ Metabolism and different factor affecting metabolism
2. Discuss Phase I/ Non synthetic/functionalization reaction and Phase II/ Synthetic/ Conjugation reaction
3. Explain drug induction and drug inhibition
Reference:
Reference: • K D Tripathi. Essentials of Medical Pharmacology. Seventh Edition. Jaypee
Publication. Page no:23-29.
www.linkedin.com/in/dr-aboobecker-siddique-p-a-200783a0
pharmacokinetics 2
fate of a drug
biotransformation :
Chemical alteration of the drug in a living organism is called bio-transformation.
Lipid soluble →Water soluble
So that not reabsorbed in Kidney
Site-Mainly liver
Others-Kidney, lungs, plasma, gut mucosa & skin
metabolism
xenonbiotics
microsomal enzyme induction
excretion
kinetics of elimination
pharmacokinetics- action of body on the drug. includes absorption, dissolution, metabolism and excretion of drug. In this presentation metabolism and excretion of the drug are covered . Includes conversion of lipophilic / non-water soluble compounds into easily removable compounds by the action of hepatic enzymes which can be microsomal or non-microsomal . Excretion is further removal or elimination of compounds or agents from the body. Drug elimination is the sum of the processes of removing an administered drug from the body. In the pharmacokinetic ADME scheme (absorption, distribution, metabolism, and excretion), it is frequently considered to encompass both metabolism and excretion. Hydrophobic drugs, to be excreted, must undergo metabolic modification making them more polar. Hydrophilic drugs, on the other hand, can undergo excretion directly, without the need for metabolic changes to their molecular structures. Introduction
Most drugs are xenobiotics, ie, chemical substances not naturally produced by the body. Xenobiotics undergo various body processes for detoxification, thus reducing their toxicity and allowing them to be readily available for excretion. These processes allow for the chemical modification of drugs into their metabolites and are known as drug metabolism or metabolic biotransformation.
These metabolites are the byproducts of drug metabolism and can be characterized by active, inactive, and toxic metabolites. Active metabolites are biochemically active compounds with therapeutic effects, whereas inactive metabolites are biochemically inactive compounds with neither a therapeutic nor toxic effect. Toxic metabolites are biochemically active compounds similar to active metabolites but have various harmful effects.
Drug metabolism occurs at a specific location in the body, resulting in a low concentration of active metabolites in the systemic circulation. This phenomenon is called first-pass metabolism because it limits drug bioavailability. First-pass metabolism primarily occurs in the liver; however, metabolizing enzymes can be found throughout the body.
Understanding these alterations in chemical activity is crucial in utilizing the optimal pharmacological intervention for any patient. This is a topic of interest to any provider who routinely treats patients with medications. The metabolism of pharmaceutical drugs is an important aspect of pharmacology and medicine. For example, the rate of metabolism determines the duration and intensity of a drug's pharmacologic action. Drug metabolism also affects multidrug resistance in infectious diseases and in chemotherapy for cancer, and the actions of some drugs as substrates or inhibitors of enzymes involved in xenobiotic metabolism are a common reason for hazardous drug interactions. These pathways are also important in environmental science, with the xenobiotic metabolism of microorganisms determining whether a pollutant will be broken down or not is covered.pharmacokinetic
biotransformation of drug
Biotransformation/Xenobiotic metabolism/ drug metabolism/detoxification.
-Xenobiotics: a wide variety of foreign compounds to which humans get exposed in day to day life.
-It includes unknown compounds, drugs, environmental pollutants, toxins.
-Many xenobiotics can evoke biological responses.
DEFINITION
The biochemical alteration of drug or xenobiotic in the presence of various enzymes that acts as a catalyst which themselves not consumed in the reaction and there by may activate or deactivate the drug is called biotransformation.
Why Biotransformation is necessary?:
To easily eliminate the drug
To terminate drug action by inactivating it
Consequences of Biotransformation
Active to Inactive:
Phenobarbitone---- Hydroxyphenobarbitone
Inactive (prodrug) to Active :
L-Dopa ---- Dopamine
Parathion -- Paraoxon
Talampicillin -- Ampicillin
Active to equally active:
Diazepam -- Oxazepam
Amitriptyline -- Nortriptyline
Imipramine -- Des-imipramine
Codeine -- Morphine
Sites of biotransformation
In the body: Liver, small and large intestines, lungs, skin, kidney, nasal mucosa & brain.
Liver is considered “metabolite clearing house” for both endogenous substances and xenobiotics.
Intestines are considered “initial site of drug metabolism”.
FIRST PASS METABOLISM:
First pass metabolism or presystemic
metabolism or ‘first pass effect’
After oral administeration many drugs are absorbed from the small intestine - transported first via portal system to the liver, where they undergo extensive metabolism before reaching systemic circulation.
fundamental concepts in drug biotransformation
Lipid soluble drugs are poorly excreted in the urine. They tend to store in fat and/or circulate until they are converted (phase I biotransformation) to more water soluble metabolites or metabolites that conjugate (phase II biotransformation) with water soluble substances.
Water soluble drugs are more readily excreted in the urine. They may be metabolized, but generally not by the CYP enzyme systems.
Enzymes catalyzing phase I biotransformation reactions
Enzymes catalyzing phase I biotransformation reactions include:
cytochrome P-450
aldehyde and alcohol dehydrogenase
deaminases
esterases
amidases
epoxide hydratases
Addition of water
Cleavage of R-O or R-N bond accompanied by addition of H2O
CYTOCHROME P450
The cytochrome P-450 families are referred to using an arabic numeral, e.g., CYP1, CYP2, etc.
Each family has a number of subfamilies denoted by an upper case letter, e.g., CYP2A, CYP2B, etc.
The individual enzymes within each subfamily are denoted by another arabic numeral, e.g., CYP3A1, CYP3A2, etc.
HOT NEW PRODUCT! BIG SALES FAST SHIPPING NOW FROM CHINA!! EU KU DB BK substit...GL Anaacs
Contact us if you are interested:
Email / Skype : kefaya1771@gmail.com
Threema: PXHY5PDH
New BATCH Ku !!! MUCH IN DEMAND FAST SALE EVERY BATCH HAPPY GOOD EFFECT BIG BATCH !
Contact me on Threema or skype to start big business!!
Hot-sale products:
NEW HOT EUTYLONE WHITE CRYSTAL!!
5cl-adba precursor (semi finished )
5cl-adba raw materials
ADBB precursor (semi finished )
ADBB raw materials
APVP powder
5fadb/4f-adb
Jwh018 / Jwh210
Eutylone crystal
Protonitazene (hydrochloride) CAS: 119276-01-6
Flubrotizolam CAS: 57801-95-3
Metonitazene CAS: 14680-51-4
Payment terms: Western Union,MoneyGram,Bitcoin or USDT.
Deliver Time: Usually 7-15days
Shipping method: FedEx, TNT, DHL,UPS etc.Our deliveries are 100% safe, fast, reliable and discreet.
Samples will be sent for your evaluation!If you are interested in, please contact me, let's talk details.
We specializes in exporting high quality Research chemical, medical intermediate, Pharmaceutical chemicals and so on. Products are exported to USA, Canada, France, Korea, Japan,Russia, Southeast Asia and other countries.
Ozempic: Preoperative Management of Patients on GLP-1 Receptor Agonists Saeid Safari
Preoperative Management of Patients on GLP-1 Receptor Agonists like Ozempic and Semiglutide
ASA GUIDELINE
NYSORA Guideline
2 Case Reports of Gastric Ultrasound
At the end of this e-learning session students will learn:
1. Definition of biotransformation/ Metabolism and different factor affecting metabolism
2. Discuss Phase I/ Non synthetic/functionalization reaction and Phase II/ Synthetic/ Conjugation reaction
3. Explain drug induction and drug inhibition
Reference:
Reference: • K D Tripathi. Essentials of Medical Pharmacology. Seventh Edition. Jaypee
Publication. Page no:23-29.
www.linkedin.com/in/dr-aboobecker-siddique-p-a-200783a0
pharmacokinetics 2
fate of a drug
biotransformation :
Chemical alteration of the drug in a living organism is called bio-transformation.
Lipid soluble →Water soluble
So that not reabsorbed in Kidney
Site-Mainly liver
Others-Kidney, lungs, plasma, gut mucosa & skin
metabolism
xenonbiotics
microsomal enzyme induction
excretion
kinetics of elimination
pharmacokinetics- action of body on the drug. includes absorption, dissolution, metabolism and excretion of drug. In this presentation metabolism and excretion of the drug are covered . Includes conversion of lipophilic / non-water soluble compounds into easily removable compounds by the action of hepatic enzymes which can be microsomal or non-microsomal . Excretion is further removal or elimination of compounds or agents from the body. Drug elimination is the sum of the processes of removing an administered drug from the body. In the pharmacokinetic ADME scheme (absorption, distribution, metabolism, and excretion), it is frequently considered to encompass both metabolism and excretion. Hydrophobic drugs, to be excreted, must undergo metabolic modification making them more polar. Hydrophilic drugs, on the other hand, can undergo excretion directly, without the need for metabolic changes to their molecular structures. Introduction
Most drugs are xenobiotics, ie, chemical substances not naturally produced by the body. Xenobiotics undergo various body processes for detoxification, thus reducing their toxicity and allowing them to be readily available for excretion. These processes allow for the chemical modification of drugs into their metabolites and are known as drug metabolism or metabolic biotransformation.
These metabolites are the byproducts of drug metabolism and can be characterized by active, inactive, and toxic metabolites. Active metabolites are biochemically active compounds with therapeutic effects, whereas inactive metabolites are biochemically inactive compounds with neither a therapeutic nor toxic effect. Toxic metabolites are biochemically active compounds similar to active metabolites but have various harmful effects.
Drug metabolism occurs at a specific location in the body, resulting in a low concentration of active metabolites in the systemic circulation. This phenomenon is called first-pass metabolism because it limits drug bioavailability. First-pass metabolism primarily occurs in the liver; however, metabolizing enzymes can be found throughout the body.
Understanding these alterations in chemical activity is crucial in utilizing the optimal pharmacological intervention for any patient. This is a topic of interest to any provider who routinely treats patients with medications. The metabolism of pharmaceutical drugs is an important aspect of pharmacology and medicine. For example, the rate of metabolism determines the duration and intensity of a drug's pharmacologic action. Drug metabolism also affects multidrug resistance in infectious diseases and in chemotherapy for cancer, and the actions of some drugs as substrates or inhibitors of enzymes involved in xenobiotic metabolism are a common reason for hazardous drug interactions. These pathways are also important in environmental science, with the xenobiotic metabolism of microorganisms determining whether a pollutant will be broken down or not is covered.pharmacokinetic
biotransformation of drug
Biotransformation/Xenobiotic metabolism/ drug metabolism/detoxification.
-Xenobiotics: a wide variety of foreign compounds to which humans get exposed in day to day life.
-It includes unknown compounds, drugs, environmental pollutants, toxins.
-Many xenobiotics can evoke biological responses.
DEFINITION
The biochemical alteration of drug or xenobiotic in the presence of various enzymes that acts as a catalyst which themselves not consumed in the reaction and there by may activate or deactivate the drug is called biotransformation.
Why Biotransformation is necessary?:
To easily eliminate the drug
To terminate drug action by inactivating it
Consequences of Biotransformation
Active to Inactive:
Phenobarbitone---- Hydroxyphenobarbitone
Inactive (prodrug) to Active :
L-Dopa ---- Dopamine
Parathion -- Paraoxon
Talampicillin -- Ampicillin
Active to equally active:
Diazepam -- Oxazepam
Amitriptyline -- Nortriptyline
Imipramine -- Des-imipramine
Codeine -- Morphine
Sites of biotransformation
In the body: Liver, small and large intestines, lungs, skin, kidney, nasal mucosa & brain.
Liver is considered “metabolite clearing house” for both endogenous substances and xenobiotics.
Intestines are considered “initial site of drug metabolism”.
FIRST PASS METABOLISM:
First pass metabolism or presystemic
metabolism or ‘first pass effect’
After oral administeration many drugs are absorbed from the small intestine - transported first via portal system to the liver, where they undergo extensive metabolism before reaching systemic circulation.
fundamental concepts in drug biotransformation
Lipid soluble drugs are poorly excreted in the urine. They tend to store in fat and/or circulate until they are converted (phase I biotransformation) to more water soluble metabolites or metabolites that conjugate (phase II biotransformation) with water soluble substances.
Water soluble drugs are more readily excreted in the urine. They may be metabolized, but generally not by the CYP enzyme systems.
Enzymes catalyzing phase I biotransformation reactions
Enzymes catalyzing phase I biotransformation reactions include:
cytochrome P-450
aldehyde and alcohol dehydrogenase
deaminases
esterases
amidases
epoxide hydratases
Addition of water
Cleavage of R-O or R-N bond accompanied by addition of H2O
CYTOCHROME P450
The cytochrome P-450 families are referred to using an arabic numeral, e.g., CYP1, CYP2, etc.
Each family has a number of subfamilies denoted by an upper case letter, e.g., CYP2A, CYP2B, etc.
The individual enzymes within each subfamily are denoted by another arabic numeral, e.g., CYP3A1, CYP3A2, etc.
HOT NEW PRODUCT! BIG SALES FAST SHIPPING NOW FROM CHINA!! EU KU DB BK substit...GL Anaacs
Contact us if you are interested:
Email / Skype : kefaya1771@gmail.com
Threema: PXHY5PDH
New BATCH Ku !!! MUCH IN DEMAND FAST SALE EVERY BATCH HAPPY GOOD EFFECT BIG BATCH !
Contact me on Threema or skype to start big business!!
Hot-sale products:
NEW HOT EUTYLONE WHITE CRYSTAL!!
5cl-adba precursor (semi finished )
5cl-adba raw materials
ADBB precursor (semi finished )
ADBB raw materials
APVP powder
5fadb/4f-adb
Jwh018 / Jwh210
Eutylone crystal
Protonitazene (hydrochloride) CAS: 119276-01-6
Flubrotizolam CAS: 57801-95-3
Metonitazene CAS: 14680-51-4
Payment terms: Western Union,MoneyGram,Bitcoin or USDT.
Deliver Time: Usually 7-15days
Shipping method: FedEx, TNT, DHL,UPS etc.Our deliveries are 100% safe, fast, reliable and discreet.
Samples will be sent for your evaluation!If you are interested in, please contact me, let's talk details.
We specializes in exporting high quality Research chemical, medical intermediate, Pharmaceutical chemicals and so on. Products are exported to USA, Canada, France, Korea, Japan,Russia, Southeast Asia and other countries.
Ozempic: Preoperative Management of Patients on GLP-1 Receptor Agonists Saeid Safari
Preoperative Management of Patients on GLP-1 Receptor Agonists like Ozempic and Semiglutide
ASA GUIDELINE
NYSORA Guideline
2 Case Reports of Gastric Ultrasound
The prostate is an exocrine gland of the male mammalian reproductive system
It is a walnut-sized gland that forms part of the male reproductive system and is located in front of the rectum and just below the urinary bladder
Function is to store and secrete a clear, slightly alkaline fluid that constitutes 10-30% of the volume of the seminal fluid that along with the spermatozoa, constitutes semen
A healthy human prostate measures (4cm-vertical, by 3cm-horizontal, 2cm ant-post ).
It surrounds the urethra just below the urinary bladder. It has anterior, median, posterior and two lateral lobes
It’s work is regulated by androgens which are responsible for male sex characteristics
Generalised disease of the prostate due to hormonal derangement which leads to non malignant enlargement of the gland (increase in the number of epithelial cells and stromal tissue)to cause compression of the urethra leading to symptoms (LUTS
New Drug Discovery and Development .....NEHA GUPTA
The "New Drug Discovery and Development" process involves the identification, design, testing, and manufacturing of novel pharmaceutical compounds with the aim of introducing new and improved treatments for various medical conditions. This comprehensive endeavor encompasses various stages, including target identification, preclinical studies, clinical trials, regulatory approval, and post-market surveillance. It involves multidisciplinary collaboration among scientists, researchers, clinicians, regulatory experts, and pharmaceutical companies to bring innovative therapies to market and address unmet medical needs.
Knee anatomy and clinical tests 2024.pdfvimalpl1234
This includes all relevant anatomy and clinical tests compiled from standard textbooks, Campbell,netter etc..It is comprehensive and best suited for orthopaedicians and orthopaedic residents.
Explore natural remedies for syphilis treatment in Singapore. Discover alternative therapies, herbal remedies, and lifestyle changes that may complement conventional treatments. Learn about holistic approaches to managing syphilis symptoms and supporting overall health.
ARTIFICIAL INTELLIGENCE IN HEALTHCARE.pdfAnujkumaranit
Artificial intelligence (AI) refers to the simulation of human intelligence processes by machines, especially computer systems. It encompasses tasks such as learning, reasoning, problem-solving, perception, and language understanding. AI technologies are revolutionizing various fields, from healthcare to finance, by enabling machines to perform tasks that typically require human intelligence.
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Ve...kevinkariuki227
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
Recomendações da OMS sobre cuidados maternos e neonatais para uma experiência pós-natal positiva.
Em consonância com os ODS – Objetivos do Desenvolvimento Sustentável e a Estratégia Global para a Saúde das Mulheres, Crianças e Adolescentes, e aplicando uma abordagem baseada nos direitos humanos, os esforços de cuidados pós-natais devem expandir-se para além da cobertura e da simples sobrevivência, de modo a incluir cuidados de qualidade.
Estas diretrizes visam melhorar a qualidade dos cuidados pós-natais essenciais e de rotina prestados às mulheres e aos recém-nascidos, com o objetivo final de melhorar a saúde e o bem-estar materno e neonatal.
Uma “experiência pós-natal positiva” é um resultado importante para todas as mulheres que dão à luz e para os seus recém-nascidos, estabelecendo as bases para a melhoria da saúde e do bem-estar a curto e longo prazo. Uma experiência pós-natal positiva é definida como aquela em que as mulheres, pessoas que gestam, os recém-nascidos, os casais, os pais, os cuidadores e as famílias recebem informação consistente, garantia e apoio de profissionais de saúde motivados; e onde um sistema de saúde flexível e com recursos reconheça as necessidades das mulheres e dos bebês e respeite o seu contexto cultural.
Estas diretrizes consolidadas apresentam algumas recomendações novas e já bem fundamentadas sobre cuidados pós-natais de rotina para mulheres e neonatos que recebem cuidados no pós-parto em unidades de saúde ou na comunidade, independentemente dos recursos disponíveis.
É fornecido um conjunto abrangente de recomendações para cuidados durante o período puerperal, com ênfase nos cuidados essenciais que todas as mulheres e recém-nascidos devem receber, e com a devida atenção à qualidade dos cuidados; isto é, a entrega e a experiência do cuidado recebido. Estas diretrizes atualizam e ampliam as recomendações da OMS de 2014 sobre cuidados pós-natais da mãe e do recém-nascido e complementam as atuais diretrizes da OMS sobre a gestão de complicações pós-natais.
O estabelecimento da amamentação e o manejo das principais intercorrências é contemplada.
Recomendamos muito.
Vamos discutir essas recomendações no nosso curso de pós-graduação em Aleitamento no Instituto Ciclos.
Esta publicação só está disponível em inglês até o momento.
Prof. Marcus Renato de Carvalho
www.agostodourado.com
Prix Galien International 2024 Forum ProgramLevi Shapiro
June 20, 2024, Prix Galien International and Jerusalem Ethics Forum in ROME. Detailed agenda including panels:
- ADVANCES IN CARDIOLOGY: A NEW PARADIGM IS COMING
- WOMEN’S HEALTH: FERTILITY PRESERVATION
- WHAT’S NEW IN THE TREATMENT OF INFECTIOUS,
ONCOLOGICAL AND INFLAMMATORY SKIN DISEASES?
- ARTIFICIAL INTELLIGENCE AND ETHICS
- GENE THERAPY
- BEYOND BORDERS: GLOBAL INITIATIVES FOR DEMOCRATIZING LIFE SCIENCE TECHNOLOGIES AND PROMOTING ACCESS TO HEALTHCARE
- ETHICAL CHALLENGES IN LIFE SCIENCES
- Prix Galien International Awards Ceremony
- Video recording of this lecture in English language: https://youtu.be/lK81BzxMqdo
- Video recording of this lecture in Arabic language: https://youtu.be/Ve4P0COk9OI
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
- Link to NephroTube website: www.NephroTube.com
- Link to NephroTube social media accounts: https://nephrotube.blogspot.com/p/join-nephrotube-on-social-media.html
Tom Selleck Health: A Comprehensive Look at the Iconic Actor’s Wellness Journeygreendigital
Tom Selleck, an enduring figure in Hollywood. has captivated audiences for decades with his rugged charm, iconic moustache. and memorable roles in television and film. From his breakout role as Thomas Magnum in Magnum P.I. to his current portrayal of Frank Reagan in Blue Bloods. Selleck's career has spanned over 50 years. But beyond his professional achievements. fans have often been curious about Tom Selleck Health. especially as he has aged in the public eye.
Follow us on: Pinterest
Introduction
Many have been interested in Tom Selleck health. not only because of his enduring presence on screen but also because of the challenges. and lifestyle choices he has faced and made over the years. This article delves into the various aspects of Tom Selleck health. exploring his fitness regimen, diet, mental health. and the challenges he has encountered as he ages. We'll look at how he maintains his well-being. the health issues he has faced, and his approach to ageing .
Early Life and Career
Childhood and Athletic Beginnings
Tom Selleck was born on January 29, 1945, in Detroit, Michigan, and grew up in Sherman Oaks, California. From an early age, he was involved in sports, particularly basketball. which played a significant role in his physical development. His athletic pursuits continued into college. where he attended the University of Southern California (USC) on a basketball scholarship. This early involvement in sports laid a strong foundation for his physical health and disciplined lifestyle.
Transition to Acting
Selleck's transition from an athlete to an actor came with its physical demands. His first significant role in "Magnum P.I." required him to perform various stunts and maintain a fit appearance. This role, which he played from 1980 to 1988. necessitated a rigorous fitness routine to meet the show's demands. setting the stage for his long-term commitment to health and wellness.
Fitness Regimen
Workout Routine
Tom Selleck health and fitness regimen has evolved. adapting to his changing roles and age. During his "Magnum, P.I." days. Selleck's workouts were intense and focused on building and maintaining muscle mass. His routine included weightlifting, cardiovascular exercises. and specific training for the stunts he performed on the show.
Selleck adjusted his fitness routine as he aged to suit his body's needs. Today, his workouts focus on maintaining flexibility, strength, and cardiovascular health. He incorporates low-impact exercises such as swimming, walking, and light weightlifting. This balanced approach helps him stay fit without putting undue strain on his joints and muscles.
Importance of Flexibility and Mobility
In recent years, Selleck has emphasized the importance of flexibility and mobility in his fitness regimen. Understanding the natural decline in muscle mass and joint flexibility with age. he includes stretching and yoga in his routine. These practices help prevent injuries, improve posture, and maintain mobilit
2. Pharmacokinetics is the study of drug movement in, through and out of the body (ADME)
PHARMACOKINETICS
3. METABOLISM / BIOTRANSFORMATION
• the process of biochemical alteration of the drug in the body
• convert the nonpolar, lipid soluble drugs into more polar, water-soluble compounds
• So that the given drug is easily excreted
Sites of
Metabolism
Liver
Kidney
Intestine lungs
plasma
EFFECT OF
METABOLISM
DESCRIPTION EXAMPLE
Inactivation
Drugs/ active metabolite
inactive compound
propranolol 4-hydroxyl
propranolol
Formation of active
metabolite
Active drug active metabolite
diazepam oxazepam
Activation of inactive
drug
Pro drugs active drugs Levodopa dopamine
Formation of toxic
metabolite
Drug active metabolite
(toxic in nature)
Paracetamol NAPQI
(hepatotoxicity)
NAPQI
N-acetyl-p-
benzoquinoneimine
4.
5. METABOLIC ENZYMES:
Microsomal enzymes
• In liver
• CYP450
• CYP3A4-
Responsible for the
metabolism of more
than 50% of drug
Non microsomal
enzymes
• Cytoplasm &
mitochondria of
liver cell, plasma &
other tissues
• Ex. Esterase,
amidase
6.
7. PHASE 1 / NON SYNTHETIC / FUNCTIONALISATION REACTION:
• convert the drug to a more polar metabolite
• Through oxidation, reduction or hydrolysis
OXIDATION:
• addition of oxygen or removal of hydrogen
• Most important
• Catalysed by mono oxygenases present in liver
• a system which includes cytochrome P450, NADPH and molecular oxygen
Types of oxidative reaction
Microsomal
oxidation
S-oxidation (sulfoxidation) Cimetidine cimetidine sulfoxide
N-oxidation Dapsone hydroxylamine dapson
Dealkylation Codeine Morphine
Hydroxylation Phenytoin hydroxyphenytoin
Deamination Amphetamine Benzyl methyl ketone
Non microsomal
oxidation
Ethyl alcohol CO2 + H2O
8. REDUCTION:
• Catalysed by microsomal or non-microsomal enzymes
HYDROLYSIS:
• cleavage of drug molecule by taking up a molecule of water
• occurs in liver, intestines, plasma and other tissues.
• choline esters, procaine, lidocaine, procainamide, aspirin, carbamazepine-epoxide, pethidine, oxytocin
Types of reductive reaction
Microsomal
reduction
Nitro reduction Chloramphenicol Arylamine
Keto reduction Cortisone hydrocortisone
Non microsomal
reduction
Disulfiram and nitrites
9. CYCLISATION
• Formation of ring structure
• Ex. Proguanil to cycloguanil
DECYCLISATION
• Opening of ring structure
• Ex. Barbiturates, Phenytoin
Some other phase 1 reactions
If the metabolite of phase I reaction is not sufficiently polar to be excreted, it undergoes phase II reactions.
10. PHASE 2 / SYNTHETIC / CONJUGATION REACTION
• involve conjugation of the drug or its phase I metabolite with an endogenous substrate
• to form a polar highly ionized organic acid, which is easily excreted in urine or bile.
• have high energy requirement.
GLUCURONIDE CONJUGATION (GLUCORONIDATION):
• Conjugation with glucoronic acid
• increases the mol wt. of the drug which favours its excretion in bile.
• Most important
• Enzyme: UDP-glucuronosyl transferases (UGTs).
GTs are found in
most of the cells,
but found
abundantly in
Liver
11. ACETYL CONJUGATION (ACETYLATION):
• Non microsomal
• Enzyme: N-acetyl transferases (NATs)
• conjugated with the help of acetyl coenzyme-A
• Ex: sulfonamides
METHYL CONJUGATION (METHYLATION):
• Non microsomal
• Enzyme: Methyl transferases (MTs)
• conjugated with the help of methyl donors
• Amines and phenols
• Ex. Captopril, methyl dopa
SULPHATE CONJUGATION (SULFATION):
• Non microsomal
• Enzyme: Sulfo transferases (SULTs)
• Steroids, phenolic compounds
• Ex. Minoxidil
12. GLUTATHIONE CONJUGATION:
• Non microsomal
• Enzyme: glutathione-S-transferase (GSTs)
• epoxides and drugs with nitrate groups
• inactivates highly reactive intermediates formed during the metabolism of drugs
• Ex. Paracetamol
AMINOACID CONJUGATION:
• Non microsomal
• Conjugation with aminoacids
• Enzyme: N-acyl transferase
• Acidic drugs
GLYCINE CONJUGATION:
• Non microsomal
• Conjugation with glycines
• Ex. salicylates
Hoffman elimination
Some drugs undergo a unique type
of metabolism: they are
metabolised by spontaneous
degradation due to spontaneous
molecular rearrangement in
plasma and tissues
e.g. atracurium
13. FIRST PASS (PRESYSTEMIC) METABOLISM
• metabolism of a drug during its passage from the site of
absorption into the systemic circulation.
• All orally administered drugs are exposed to drug
metabolizing enzymes in the intestinal wall and liver
• can be avoided by administering the drug through
sublingual, transdermal or parenteral routes.
• The extent of FPM differs for different drugs
• an important determinant of oral bioavailability
14. Attributes of drugs with high first pass metabolism:
(a) Higher Oral dose.
(b) Individual variation in the oral dose (due to differences in the extent of FPM)
(c) Oral bioavailability is apparently increased in patients with severe liver disease.
(d) Oral bioavailability of a drug is increased if another drug competing with it in FPM is given
concurrently, e.g. chlorpromazine and propranolol
15. FACTORS AFFECTING DRUG METABOLISM:
• Chemical factors
• Enzyme induction
• Enzyme inhibition
• Biological factors
• Age
• Diet
• Sex difference
• Concomitant diseases
• Physiochemical properties of the drug
• Lipo philicity
• Hydro philicity
• Molecular weight