Pharmacokinetics, sometimes described as what the body does to a drug, refers to the movement of drug into, through, and out of the body—the time course of its absorption, bioavailability, distribution, metabolism, and excretion.
This file contains the rout of absorption of the drug. the events drug pass through before reaching the systemic circulation. Also contains a little introduction of First Pass Mechanism.
This file contains the rout of absorption of the drug. the events drug pass through before reaching the systemic circulation. Also contains a little introduction of First Pass Mechanism.
Pharmacokinetics is the study of the movement of drug molecules in the body. It includes absorption, distribution, metabolism, and excretion of drugs. Pharmacokinetics is the study of what happens to drugs once they enter the body (the movement of the drugs into, within, and out of the body). For a drug to produce its specific response, it should be present in adequate concentrations at the site of action. This depends on various factors apart from the dose.
Four pharmacokinetic properties determine the onset, intensity, and the duration of drug action (Figure 1.6.1):
• Absorption: First, absorption from the site of administration permits entry of the drug (either directly or indirectly) into plasma.
• Distribution: Second, the drug may then reversibly leave the bloodstream and distribute it into the interstitial and intracellular fluids.
• Metabolism: Third, the drug may be biotransformed by metabolism by the liver or other tissues.
• Elimination: Finally, the drug and its metabolites are eliminated from the body in urine, bile, or feces.
In short, pharmacokinetics means what the body does to the drug.
Presentation covers the basics of pharmacokinetic. Mechanism for the transport of drug molecule. Absorption, factors affecting on absorption of drugs. Concept of bioavailability. Distribution, plasma protein binding, tissue binding, barriers.
Pharmacokinetics is the study of the movement of drug molecules in the body. It includes absorption, distribution, metabolism, and excretion of drugs. Pharmacokinetics is the study of what happens to drugs once they enter the body (the movement of the drugs into, within, and out of the body). For a drug to produce its specific response, it should be present in adequate concentrations at the site of action. This depends on various factors apart from the dose.
Four pharmacokinetic properties determine the onset, intensity, and the duration of drug action (Figure 1.6.1):
• Absorption: First, absorption from the site of administration permits entry of the drug (either directly or indirectly) into plasma.
• Distribution: Second, the drug may then reversibly leave the bloodstream and distribute it into the interstitial and intracellular fluids.
• Metabolism: Third, the drug may be biotransformed by metabolism by the liver or other tissues.
• Elimination: Finally, the drug and its metabolites are eliminated from the body in urine, bile, or feces.
In short, pharmacokinetics means what the body does to the drug.
Presentation covers the basics of pharmacokinetic. Mechanism for the transport of drug molecule. Absorption, factors affecting on absorption of drugs. Concept of bioavailability. Distribution, plasma protein binding, tissue binding, barriers.
Dosage form design - Biopharmaceutical considerationAniruddha Roy
Dosage form design - Biopharmaceutical consideration: Understanding how physicochemical characteristics of a drug and formulation component affect bioactivity
Bioavailability and bioequivalence
Bioavailability-
Whenever a drug is given by oral route it has to go through certain pathway to reach the systemic circulation. Eg. If 100 mg drug is given orally, and if 80 mg is absorbed and 20 mg gets excreted then 80 mg absorbed drug reaches liver through portal system. In liver it gets metabolized, here if 30 mg gets metabolized by the liver 50 mg reaches the systemic circulation in the unchanged from. But Bioavailability is expressed in mg it has to be expressed in fraction. So Bioavailability is basically the fraction of unchanged from of the drug that reaches the systemic circulation following administration by any route.
As the drug given by intravenous route reaches directly into the systemic circulation. So the Bioavailability of drug given i.v is 100 %. % Bioavailability can be calculated as- Area under the curve (AUC oral)/ (AUC i.v) *100.
Bioavailability depends on both the rate and extent of absorption.
Rate of absorption depends on- site of adminstration and the drug formulation.
Extent (amount) of absorption depends on- route of drug administration
Factors affecting absorption and Bioavailability-
Pharmaceutical and pharmacological factors:
Pharmaceutical factors include- particle size, crystal from, salt form, water of hydration, Nature of excipients and adjuvants, degree of ionisation.
Pharmacological factors- gastric emptying & g.i mobility, g.i diseases, food and other substances, first-pass effect, Drug-drug interaction, pharmacogenetics, miscellaneous factors like route of administration, area of absorbing surface, state of circulation at site of absorption.
Whenever a drug is given orally it has to go through certain pathway to reach systemic circulation.
E.g out of 100 mg drug given orally if 80 mg gets absorbed & 20 gets excreted. 80 mg of absorbed drug then reaches the liver through portal vein. Liver is highly saturated with enzymes so it doesn't allow the drug to pass freely through it without metabolizing certain amount of drug. . So if 30 mg of absorbed drug gets metabolized in the liver remaining 50 mg of drug reaches the systemic circulation in the unchanged form. But Bioavailability is never expressed in mg it is always expressed in fraction. So Bioavailability is basically the fraction of unchanged from of the drug that reaches the systemic circulation following administration by any route.
Whenever drug is given intravenously 100% drug reaches the systemic circulation in an unchanged form. So the Bioavailability of the drug given intravenously is 100%, while that of the drug given orally is < 100%
Bioavailability of a drug depends on the rate and extent of absorption.
Rate of drug administration is determined by: site of drug administration and drug formulation.
Extent (amount) of drug absorption is determined by: route of drug administration.
Factors affecting drug absorption and Bioavailability- There are various pharmaceutical and pharmacological factors that affect the drug absorption.
FIRST PASS METABOLISM:-
The drug given orally first pass through GI wall and then reaches the liver through portal system. The drug can also be metabolized in the gut wall CYP3A4 enzyme which is a substrate for P-gp {P-glycoprotein (P-gp) is an active transporter which pumps drug out of the gut wall cells back into the gut lumen against the concentration gradient.) Normally, drug enters the intestinal lumen by passive diffusion (i.e along the concentration gradient). But P-gp causes drug efflux or drug wastage (i.e against the concentration gradient); The amount of drug that disappears contribute first pass metabolism. But first pass metabolism occur in LIVER > INTESTINE.
Some amount of drug while passing through the liver gets metabolized in the liver for the first time before reaching the systemic circulation this known as first pass metabolism.
Bioequivalence- it as comparison of 2 different brand products of a same drug.
E.g. if Drug company X designs a new drug - (BRANDED DRUG) it gets patency for suppose 20 yrs. So that no other company can legally copy this drug. But once the patency expires any other company can legally copy this drug (GENERIC DRUG) but requires approval by FDA. and FDA asks for BIOEQUIVALENCE certificate (i.e it checks if the compound produced by other company is equivalent to that of BRANDED DRUG.) It has to prove that amount as well as rate of absorption is similar. No company can copy the drug 100% as it is. therefore the acceptable range is +/- 20-25%. The drug can be chemically, pharmaceutically, Therapeutically & clinically equivalent.
Thank you
Pharmacology Experiment based Questions With Answer KeysA M O L D E O R E
MSBTE Pharmacology Practical Exam for Diploma in pharmacy students in Maharashtra.
Experimental pharmacology for D. Pharmacy Students
Pharmacology Experiment based Questions
PCI New Syllabus ER2020
Course Code: 20056
Antidepressants are a class of medication used to treat major depressive disorder, anxiety disorders, chronic pain conditions and to help manage addictions. Common side-effects of antidepressants include dry mouth, weight gain, dizziness, headaches, sexual dysfunction, and emotional blunting
Anatomy and physiology are two of the most basic terms and areas of study in the life sciences. Anatomy refers to the internal and external structures of the body and their physical relationships, whereas physiology refers to the study of the functions of those structures.
Animal cells are typical of the eukaryotic cell, enclosed by a plasma membrane and containing a membrane-bound nucleus and organelles. Unlike the eukaryotic cells of plants and fungi, animal cells do not have a cell wall. This feature was lost in the distant past by the single-celled organisms that gave rise to the kingdom Animalia. Most cells, both animal and plant, range in size between 1 and 100 micrometers and are thus visible only with the aid of a microscope.
All living organisms are made of cells and cellular products. The cell is the smallest structural, functional, and biological unit of all living organisms. It can capable of biosynthesis, replication and energy transformation. All cellular organelles carry out specific functions that are necessary for the normal functioning of the cell. Animal cells work together and function interdependently. Human cells vary in size, shape, and function. Most animal cells are so small they can only be seen with the aid of a microscope. Based on function, there are more than 200 different kinds of animal cells that help each system contribute to the homeostasis of the entire body. Despite their many differences, human cells have several similar structural features: a cell membrane, a nucleus, and cytoplasm and cell organelles.
The term “opiate” refers only to substances with morphine-like activity that are structurally related to morphine. Opioids are sometimes referred to as “narcotic analgesics” and opioid receptor antagonists as “narcotic antagonists”
Sympatholytic drugs (Adrenergic blockers) bind to the adrenergic receptors and prevent the action of adrenergic drugs.
These are drugs which block the actions of sympathetic division or catecholamines (adrenaline and noradrenaline).
They are competitive antagonists at both α and β adrenergic receptors.
Your sympathetic nervous system is best known for its role in responding to dangerous or stressful situations.
In these situations, your sympathetic nervous system activates to speed up your heart rate, deliver more blood to areas of your body that need more oxygen or other responses to help your get out of danger.
Its nerve fibers arise from the thoracic and lumbar regions of the spinal cord.
The autonomic ganglia are the synapses between preganglionic and postganglionic neurons. The postganglionic axons then go to the visceral effectors.
Acetylcholine is a neurotransmitter releases in the preganglionic nerve endings and Noradrenaline at postganglionic nerve endings.
The drugs which mimic the action sympathetic division are called sympathomimetics.
They show similar actions as that of catecholamines.
Sympathomimetic
They act by either by directly interacting with adrenergic receptors (alpha or beta) or stimulation of the adrenergic nerve endings.
The digestive system is made up of the gastrointestinal tract—also called the GI tract or digestive tract—and the liver, pancreas, and gallbladder. ... The hollow organs that make up the GI tract are the mouth, esophagus, stomach, small intestine, large intestine, and anus.
Hemostasis or haemostasis is a process to prevent and stop bleeding, meaning to keep blood within a damaged blood vessel (the opposite of hemostasis is hemorrhage). It is the first stage of wound healing. This involves coagulation, blood changing from a liquid to a gel.
Aminocaproates.
Antifibrinolytic Agents.
Estrogens, Conjugated (USP)
Hemostatics.
Tranexamic Acid.
Aprotinin.
Deamino Arginine Vasopressin
Sulfonamides (sulphonamides) are a group of man-made (synthetic) medicines that contain the sulfonamide chemical group. They may also be called sulfa drugs. Many people use the term sulfonamide imprecisely to refer only to antibiotics that have a sulfonamide functional group in their chemical structure.
The endocrine system is a messenger system comprising feedback loops of the hormones released by internal glands of an organism directly into the circulatory system, regulating distant target organs. In vertebrates, the hypothalamus is the neural control center for all endocrine systems.
Anticoagulants are used to treat and prevent blood clots that may occur in your blood vessels. Blood clots can block blood vessels (an artery or a vein). A blocked artery stops blood and oxygen from getting to a part of your body (for example, to a part of the heart, brain or lungs).
A tissue is a group of similar cells that are specialized for a particular function.
The four basic fundamental types of body tissues are
1. Epithelial tissue
2. Connective tissue
3. Muscular tissue
4. Nervous tissue
Each type of tissue is characterized by specific functions. These tissues contribute to the overall health and maintenance of the body. These tissues combine to form organs. The various organs make up the systems of the body that allow us to function and survive in our complex world. Histology is the science that deals with the study of tissues.
In biology, the tissue is a cellular organizational level between cells and a complete organ. A tissue is an ensemble of similar cells and their extracellular matrix from the same origin that together carry out a specific function. Organs are then formed by the functional grouping together of multiple tissues.
The English word "tissue" derives from the French word "tissue", meaning that something that is "woven", from the verb tisse, "to weave".
Career scope and opportunities
Pharmacy is the health profession that links the health sciences with the chemical sciences, and it is charged with ensuring the safe and effective use of medication. The scope of pharmacy practice includes compounding and dispensing medications, and it also related to more modern services like patient care, including clinical services, reviewing medications for safety and efficacy, and providing drug information.
The demand for pharma graduates is high in sectors like - healthcare, research, manufacturing, medical marketing, pharmacovigilance etc. As a pharma graduate, you can take up job roles like - drugs inspector, drugs controller, hospital pharmacist etc.
Ever hear the term "bronchial asthma" and wonder what it means? When people talk about bronchial asthma, they are really talking about asthma, a chronic inflammatory disease of the airways that causes periodic "attacks" of coughing, wheezing, shortness of breath, and chest tightness.
According to the CDC, more than 25 million Americans, including 6.8 million children under age 18, suffer with asthma today.
Allergies are strongly linked to asthma and to other respiratory diseases such as chronic sinusitis, middle ear infections, and nasal polyps. Most interestingly, a recent analysis of people with asthma showed that those who had both allergies and asthma were much more likely to have nighttime awakening due to asthma, miss work because of asthma, and require more powerful medications to control their symptoms.
Asthma is associated with mast cells, eosinophils, and T lymphocytes. Mast cells are the allergy-causing cells that release chemicals like histamine. Histamine is the substance that causes nasal stuffiness and dripping in a cold or hay fever, constriction of airways in asthma, and itchy areas in a skin allergy. Eosinophils are a type of white blood cell associated with allergic disease. T lymphocytes are also white blood cells associated with allergy and inflammation.
These cells, along with other inflammatory cells, are involved in the development of airway inflammation in asthma that contributes to the airway hyperresponsiveness, airflow limitation, respiratory symptoms, and chronic disease. In certain individuals, the inflammation results in the feelings of chest tightness and breathlessness that's felt often at night (nocturnal asthma) or in the early morning hours. Others only feel symptoms when they exercise (called exercise-induced asthma). Because of the inflammation, the airway hyperresponsiveness occurs as a result of specific triggers.
These are substances produced by a wide variety of cells in the body, having strong biological activity. Autacoids generally act locally at the site of synthesis and release. So they have also been called ‘local hormones’. They have short duration of action. They usually exert their action at the site of inflammation, lesion and injury.
The autacoids also differ from circulating hormones in that they are produced by many tissues rather than in specific endocrine glands.
The classical autacoids are— Ex.
Histamine, Serotonin
Prostaglandins, Leukotriene, Heparin, Endothelins
Bradykinin, Angiotensin, Eicosanoids
Interleukins, TNFα (tissue necrosis factor),
Platelet activating factor
The cell is the smallest structural, functional, and biological unit of all living organisms. It can capable of biosynthesis, replication and energy transformation.
ANATOMY
Anatomy is the study of the structure or morphology of the body and the physical relationship between body parts.
PHYSIOLOGY
Physiology is the study of the functions of body parts, what they do, and how they do it.
Within the body, there are different levels of structural organization and complexity.
Parasympatholytics are the drugs that block or inhibit the actions of acetylcholine at postganglionic nerve endings and cholinergic receptors. They are also referred to as anticholinergics or cholinergic blocking agents or antispasmodics.
Anticholinergic drugs include atropine and related drugs- atropine is the prototype. Atropine is obtained from the plant Atropa belladonna. Atropine and scopolamine (hyoscine) are the belladonna alkaloids. They compete with acetylcholine for muscarinic receptors and block this receptors-they are muscarinic antagonists.
Flu Vaccine Alert in Bangalore Karnatakaaddon Scans
As flu season approaches, health officials in Bangalore, Karnataka, are urging residents to get their flu vaccinations. The seasonal flu, while common, can lead to severe health complications, particularly for vulnerable populations such as young children, the elderly, and those with underlying health conditions.
Dr. Vidisha Kumari, a leading epidemiologist in Bangalore, emphasizes the importance of getting vaccinated. "The flu vaccine is our best defense against the influenza virus. It not only protects individuals but also helps prevent the spread of the virus in our communities," he says.
This year, the flu season is expected to coincide with a potential increase in other respiratory illnesses. The Karnataka Health Department has launched an awareness campaign highlighting the significance of flu vaccinations. They have set up multiple vaccination centers across Bangalore, making it convenient for residents to receive their shots.
To encourage widespread vaccination, the government is also collaborating with local schools, workplaces, and community centers to facilitate vaccination drives. Special attention is being given to ensuring that the vaccine is accessible to all, including marginalized communities who may have limited access to healthcare.
Residents are reminded that the flu vaccine is safe and effective. Common side effects are mild and may include soreness at the injection site, mild fever, or muscle aches. These side effects are generally short-lived and far less severe than the flu itself.
Healthcare providers are also stressing the importance of continuing COVID-19 precautions. Wearing masks, practicing good hand hygiene, and maintaining social distancing are still crucial, especially in crowded places.
Protect yourself and your loved ones by getting vaccinated. Together, we can help keep Bangalore healthy and safe this flu season. For more information on vaccination centers and schedules, residents can visit the Karnataka Health Department’s official website or follow their social media pages.
Stay informed, stay safe, and get your flu shot today!
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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.
- Video recording of this lecture in English language: https://youtu.be/lK81BzxMqdo
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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.
Lung Cancer: Artificial Intelligence, Synergetics, Complex System Analysis, S...Oleg Kshivets
RESULTS: Overall life span (LS) was 2252.1±1742.5 days and cumulative 5-year survival (5YS) reached 73.2%, 10 years – 64.8%, 20 years – 42.5%. 513 LCP lived more than 5 years (LS=3124.6±1525.6 days), 148 LCP – more than 10 years (LS=5054.4±1504.1 days).199 LCP died because of LC (LS=562.7±374.5 days). 5YS of LCP after bi/lobectomies was significantly superior in comparison with LCP after pneumonectomies (78.1% vs.63.7%, P=0.00001 by log-rank test). AT significantly improved 5YS (66.3% vs. 34.8%) (P=0.00000 by log-rank test) only for LCP with N1-2. Cox modeling displayed that 5YS of LCP significantly depended on: phase transition (PT) early-invasive LC in terms of synergetics, PT N0—N12, cell ratio factors (ratio between cancer cells- CC and blood cells subpopulations), G1-3, histology, glucose, AT, blood cell circuit, prothrombin index, heparin tolerance, recalcification time (P=0.000-0.038). Neural networks, genetic algorithm selection and bootstrap simulation revealed relationships between 5YS and PT early-invasive LC (rank=1), PT N0—N12 (rank=2), thrombocytes/CC (3), erythrocytes/CC (4), eosinophils/CC (5), healthy cells/CC (6), lymphocytes/CC (7), segmented neutrophils/CC (8), stick neutrophils/CC (9), monocytes/CC (10); leucocytes/CC (11). Correct prediction of 5YS was 100% by neural networks computing (area under ROC curve=1.0; error=0.0).
CONCLUSIONS: 5YS of LCP after radical procedures significantly depended on: 1) PT early-invasive cancer; 2) PT N0--N12; 3) cell ratio factors; 4) blood cell circuit; 5) biochemical factors; 6) hemostasis system; 7) AT; 8) LC characteristics; 9) LC cell dynamics; 10) surgery type: lobectomy/pneumonectomy; 11) anthropometric data. Optimal diagnosis and treatment strategies for LC are: 1) screening and early detection of LC; 2) availability of experienced thoracic surgeons because of complexity of radical procedures; 3) aggressive en block surgery and adequate lymph node dissection for completeness; 4) precise prediction; 5) adjuvant chemoimmunoradiotherapy for LCP with unfavorable prognosis.
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
2. OIn order to get its effect, a drug must be
administered in a suitable dosage form
at appropriate site.
OIt must be absorbed effectively from the
site of administration, and distributed in
the body to reach its site of action.
OAfter its action, for the termination of its
effect, the drug must be metabolized,
and its metabolites excreted from the
body.
3. Pharmacokinetics
O Pharmacokinetics is study of the movement of
drug molecules in body.
O It includes absorption, distribution, metabolism
and excretion of drug (ADME).
O In short, pharmacokinetics means what body does
to the drug.
5. Drug absorption
O Absorption is movement of the drug from its site
of administration into the circulation. Simply
speaking, absorption is the entry of drug
molecules into blood via mucous membrane of
digestive organs, or respiratory tract or from site
of injection.
O When a drug is administered orally, it passes
through the mucus membrane of G.I.T. organs
and blood capillary membrane to enter in to the
blood circulation. When drug is given
intravenously, it enters directly in to blood.
6. Process of drug absorption on oral
administration
Oral preparation
Disintegration
Granules
Deaggregation
Fine particles
dissolution
Solution
Absorption
7. Cell membrane
O Biological cell membrane is a lipoprotein
membrane.
O The lipid portion of membrane is bilayer (double
layer) and made up of phospholipid and
cholesterol molecules.
O The proteins are located across the lipid bilayer.
The membrane contains many aqueous pores
(channels) though which filtration of small drug
molecules occur.
9. Drugs may cross body membranes
by following mechanisms
O Passive diffusion
O Filtration
O Active transport
O Facilitated diffusion
O Endocytosis
10.
11. Passive diffusion
O The lipid soluble drug can cross the cell
membrane easily by diffusion. e.g. diazepam,
propranolol etc. the drug molecules cross the
cell membrane by dissolving in lipid bilayer of
membrane. The rate of drug transfer is directly
proportional to lipid/water coefficient. Greater
the coefficient of drug, faster the diffusion of the
drug through the membrane.
12. Filtration
O Filtration is passage of drugs through aqueous
pores in the membrane or through paracellular
spaces. This can be accelerated if hydrodynamic
flow of the solvent is occurring under hydrostatic
or osmotic pressure gradient, e.g. across most
capillaries including glomeruli. Lipid-insoluble
drugs cross biological membranes by filtration if
their molecular size is smaller than the diameter of
the pores.
13. Active transport
O It means the passage of drug across the
biological membrane against their
concentration gradient with the help of carriers
by the use of energy (ATP). e.g. methyl dopa,
levodopa, 5-fluoro-uracil. It involves movement
of drug molecules from lower to higher
concentration. It is carrier mediated i.e. carries
by a specific transport protein.
14. Facilitated diffusion
O It means the passage of drug across the
biological membrane along the concentration
gradient by the protein carrier mediated system
also called as carrier mediated diffusion. It
depends on number of carrier e.g. absorption
of glucose, iron and amino acids from intestine.
15. Endocytosis
O It is the process by which the large
molecules are engulfed by the cell
membrane and releases them
intracellularly e.g. protein, toxins
17. A) Biological factors
1) Local PH of GIT organs
2) Presence of food and other drug in GIT
3) Surface area of GIT organs
4) Disease state of GIT organs
5) GIT motility
6) First pass metabolism
B) Pharmaceutical factors
1) Physical state of drug
2) Water or lipid solubility of drug
3) Chemical stability
4) Molecular weight
5) Particle size of drug
6) Disintegration time and dissolution rate
7) Enteric coating of drugs
18. Local PH of GIT organs
O Most of the drugs are weak acids or bases and
at the physiological pH of body fluids (7.4), drug
molecules exist as mixture of ionized (charged)
and unionized (free) molecular form.
O It is observed that, drugs which are more lipid
soluble exist as unionized form; whereas water
soluble drugs are exist in ionized form.
O The principle is that: “Cell membranes are
more permeable to unionized form of a drug
than to an ionized form.”
19. For examples:
O Acidic drugs like phenobarbitone and aspirin would
be in unionized form at low pH of stomach. Hence
these drugs are significantly absorbed from stomach.
O Basic drugs like amphetamine and morphine would
be in ionized form at the low pH of stomach and not
well absorbed.
O As these drugs move down in the intestine, the pH
increases and acidic drug become more ionized,
whereas basic drugs are less ionized. Therefore
absorption of basic drugs increases as the molecules
move through the intestine.
20. Presence of food and other drug in GIT
O Most drugs are better absorbed in empty stomach
but they may cause gastric irritation, nausea,
vomiting, gastric bleeding and ulcer. Presence of
food in the stomach dilutes the drug and retards
absorption of drug. e.g. ampicillin, aspirin.
O The presence of other drugs in GIT may increase or
decrease the absorption of drug due to drug-drug
interaction. e.g. Vitamin C enhances the absorption
of iron from the G.I.T. Calcium present in milk and in
antacids forms insoluble complexes with the
tetracycline antibiotics and reduces their absorption.
21. Surface area of GIT organs
O The greater the surface area of the
absorbing surface, the faster is the rate of
absorption.
O Drugs are better absorbed from the small
intestine than the stomach due to greater
surface area.
22. Disease states of GIT organs
O Absorption and first pass metabolism may
be affected in conditions like
malabsorption, thyrotoxicosis,
achlorhydria and liver cirrhosis.
23. GIT motility
O Increase in G.I.T. motility as in diarrhoea,
decreases absorption of drugs due to rapid
elimination in faeces. Vomiting also decreases
absorption of drugs.
24. First pass metabolism
O Some drugs e.g. nitroglycerin, isoprenaline,
propranolol, chlorpromazine etc. undergo first
pass metabolism in G.I.T. and liver during
hepatic portal circulation.
O It decreases their therapeutic effect. These
drugs are better administered sublingually to
reach the systemic circulation.
25.
26. Physical state of drug
O Drugs given in liquid dosage form are
better and rapidly absorbed from G.I.T.
than when given in solid dosage forms.
27. Water or lipid solubility of drug
O The biological cell membrane, mucous membrane
and blood capillary membrane are made up of
lipid bilayer. The principle is that: “Cell
membranes are more permeable to unionized
form of a drug than to an ionized form.”
O If the drug is lipid soluble then its greater fraction
exists in unionized form. Therefore lipid soluble
drugs are absorbed better and greater extent
because cell membranes are more permeable to
unionized form of a drug.
O If the drug is water soluble then its greater fraction
exists in ionized form. Hence because of
ionization water soluble drugs poorly absorbed.
28. Chemical stability
O Chemically unstable drugs are inactivated in
gastrointestinal tract.
O Penicillin-G is unstable in acid medium (acid
labile) of stomach and cannot produce
satisfactory results on oral administration.
O But penicillin-V is more stable in acid medium
of stomach (acid resistant) than penicillin-G and
therapeutically effective.
29. Molecular weight
O Drugs with high molecular weight are not
usually absorbed from gastrointestinal
tract on oral administration.
O Such drugs may be inactivated by
enzymatic degradation. e.g. insulin
undergoes enzymatic degradation in G.I.T.
and not effectively absorbed. Hence
insulin is given subcutaneously.
30. Particle size of drug
O Solid dosage form of drugs that contain smaller
particles are better absorbed from G.I.T. e.g.
aspirin, tolbutamide, griseofulvin. Smaller the
particle size of drug better will be the drug
absorption. Solid dosage form of drugs that
contain larger particles e.g. streptomycin,
neomycin are very little absorbed from G.I.T.
31. Bioavailability
O Bioavailability refers to the rate and extent of
absorption of a drug from a dosage form.
O It is a measure of the fraction (F ) of administered dose
of a drug that reaches the systemic circulation.
Bioavailability of drug injected i.v. is 100%, but is
frequently lower after oral ingestion because-
1) the drug may be incompletely absorbed.
2) the absorbed drug may undergo first pass
metabolism.
32. O Single dose bioavailability test involves an analysis
of plasma or serum concentration of the drug at
various time intervals after its oral administration
and plotting a serum concentration time curve.
AUC after oral dose
AUC after I.V. dose
X 100
Bioavailability
=
33.
34. DRUG DISTRIBUTION
O Drug distribution is the process which transports
a drug to its site of action, to other storage sites
in the body, and to the organs of metabolism
and excretion.
35. The main factors which affect
drug distribution are
O physiochemical characteristics of the drug
O route of drug administration
O plasma proteins binding of drug
O regional blood flow
36. Plasma proteins binding of drug
O After drug get absorbed or injected into systemic
blood circulation, It is distributed in various body fluid
compartments such as interstitial fluid, intracellular
fluid, cerebrospinal fluid, lymph, endolymph, GIT fluid,
aqueous humour, and plasma.
O The plasma and these body fluids contain plasma
proteins albumin, globulin and glycoprotein.
O The drug molecules bound to plasma proteins until
the equilibrium is formed with unbound drug (free
form) in plasma. But the only free drug exerts a
pharmacological action.
37. O Drug bound to proteins forms drug: plasma
protein complex. This complex does not show
pharmacological action, because it cannot cross
cellular membrane to interact with its site of
action.
O Hence Drug: plasma protein complex acts as
drug reservoir. Protein binding slows down
(delay) the drug excretion. Only free drug
capable of crossing cell membrane can show
their pharmacological action.
Drug + plasma protein Drug: plasma protein complex + unbound (free) drug
38. O As free drug molecules undergo metabolism
and excretion, drug: plasma protein complex
dissociates to supply more free drug molecules.
O There are a large number of drugs which are
more than 90% bound to plasma albumin,
O e.g. doxycycline, warfarin, indomethacin,
propranolol, chlorpropamide, imipramine and
phenytoin.
39. METABOLISM OF DRUGS
O The process of alteration in chemical structure
of drug molecule is referred as drug metabolism
or biotransformation.
O Drugs treated by the body as foreign
substances, which body tries to remove from the
body by metabolism and excretion.
40. O The sites for drug metabolism are liver,
kidney, gastrointestinal tract, lungs and
plasma. The metabolism generally results
in the conversion of a drug to a metabolite
that is less active, less lipid soluble, less
toxic and hence easily excreted.
Drug Metabolism
lessactivemetabolite excretion
41. Enzymes responsible for metabolism of drugs:
O a) Microsomal enzymes: Present in the smooth
endoplasmic reticulum of the liver, kidney and
GIT e.g. glucuronyl transferase, dehydrogenase ,
hydroxylase and cytochrome P450.
O b) Non-microsomal enzymes: Present in the
cytoplasm, mitochondria of different organs. e.g.
esterases, amidase, hydrolase.
42. Types of biotransformation
O The chemical reactions involved in
biotransformation are classified as phase-I and
phase-II (conjugation) reactions. In phase-I
reaction the drug is converted to more polar
metabolite.
43. If this metabolite is sufficiently water soluble, then
it will be excreted in urine. Some metabolites may
not be excreted and further metabolised by
phase –II reactions.
O Phase-I: Oxidation (hydroxylation,
dealkylation, deamination,
dehalogenation, sulfoxide formation),
reduction and hydrolysis.
O Phase-II: Glucuronidation, sulfate
conjugation, acetylation, glycine
conjugation and methylation reactions.
44. First pass metabolism
O First pass metabolism is a process in which a drug
administered by mouth is absorbed from the
gastrointestinal tract and transported via portal vein
to liver, where it is metabolized. As a result only a
small fraction of the active drug enters into systemic
circulation and available at its site of action. First
pass metabolism reduces bioavailability of drug. First
pass metabolism can be bypassed by giving the drug
via sublingual or other route.
O E.g. metoprolol, imipramine, cimetidine, diazepam,
nitroglycerin etc.
45. DRUG EXCRETION
O Excretion of drugs means the
transportation of drug metabolite out of
the body. The major processes of
excretion include renal excretion, biliary
excretion and pulmonary excretion. The
minor routes of excretion are saliva,
sweat, tears, breast milk, vaginal fluid,
and hair.
46. 1) Renal excretion:
The excretion of drug by the kidney involves three
stages-
O Glomerular filtration:
some drugs and drug metabolites undergo
ultrafiltration in glomerulus and enter into
glomerular filtrate. All the drugs which have low
molecular weight (5000-69000) can filter through
glomerulus. Only the free form of drug (which is not
bound with the plasma proteins) can pass through
glomerulus.
e.g. phenobarbitone, digoxin, ethambutol etc.
47. O Tubular reabsorption: The reabsorption of drug
takes place from the distal convoluted tubules into
plasma. The unionized and lipid soluble drugs in
the glomerular filtrate rapidly and completely
reabsorbed into blood.
O Tubular secretion: The cells of the proximal
convoluted tubule transport drugs from the
plasma into the tubule e.g. sulpha drugs,
cephalosporin, acetazolamide, penicillin-G,
dopamine, pethidine, thiazides etc.
48. Biliary excretion:
O Molecular weight more than 300 daltons
and polar drugs are excreted in the bile.
After excretion of drug through bile into
intestine, and then excreted in the faeces.
e.g. chloramphenicol
49. Gastrointestinal excretion:
O When a drug is administered orally, a part
of the drug is not absorbed and excreted
in the faeces. e.g. aluminium hydroxide,
ferrous sulphate.
50. Pulmonary excretion:
O Drugs that are readily vaporized, such as
many inhalation anaesthetics and alcohols
are excreted through lungs. E.g. general
anaesthetics, alcohol
51. Sweat
O A number of drugs are excreted into the
sweat e.g. rifampicin, metalloids like
arsenic and other heavy metals.
52. Mammary excretion:
O Many drugs mostly weak basic drugs are
accumulated into the milk. They may enter into
baby through breast milk and produce harmful
effects in the baby
O e.g. ampicillin, aspirin, chlordiazepoxide,
tetracycline, diazepam, furosemide, morphine,
streptomycin etc.