Laboratory "Hypoxie : Physiopathologie Cardiovasculaire et Respiratoire" (HP2) INSERM U 1042 - Université Joseph Fourier

Gilles FAURY

Animal and human pharmacology

U1042 Faculty of Biology University Joseph Fourier -

Grenoble 1

M2 Eudipharm - UCBL

DEFINITION

Pharmacology (from Greek φάρμακον, pharmakon, "poison in classic Greek; drug in modern Greek"; and -λογία, "Study of" -logia) is the branch of medicine and biology concerned with the study of drug action. More specifically, it is the study of the interactions that occur between a living organism and chemicals that affect normal or abnormal biochemical function. If substances have medicinal properties, they are considered pharmaceuticals. The field encompasses drug composition and properties, interactions, toxicology, therapy, and medical applications and antipathogenic capabilities. The two main areas of pharmacology are pharmacodynamics and pharmacokinetics. The former studies the effects of the drugs on biological systems, and the latter the effects of biological systems on the drugs. In broad terms, pharmacodynamics discusses the interactions of chemicals with biological receptors, and pharmacokinetics discusses the absorption, distribution, metabolism, and excretion of chemicals from the biological systems.

http://en.wikipedia.org/wiki/Pharmacology

A variety of topics involved with pharmacology, including neuropharmacology, renal pharmacology, human metabolism, intracellular metabolism, and intracellular regulation.

Pharmacology is not synonymous with pharmacy and the two terms are frequently confused. Pharmacology deals with how drugs interact within biological systems to affect function. It is the study of drugs, of the reactions of the body and drug on each other, the sources of drugs, their nature, and their properties. In contrast, pharmacy is a biomedical science concerned with preparation, dispensing, dosage, and the safe and effective use of medicines.

http://en.wikipedia.org/wiki/Pharmacology

The study of chemicals requires intimate knowledge of the biological system affected. With the knowledge of cell biology and biochemistry increasing, the field of pharmacology has also changed substantially. It has become possible, through molecular analysis of receptors, to design chemicals that act on specific cellular signaling or metabolic pathways by affecting sites directly on cell-surface receptors (which modulate and mediate cellular signaling pathways controlling cellular function). A chemical has, from the pharmacological point-of-view, various properties: - and pharmacodynamics describes the chemical's effect on the body (desired or toxic), >> SEE LECTURE “IN VITRO AND IN VIVO TESTING” - and pharmacokinetics describes the effect of the body on the chemical (e.g. half-life and volume of distribution), >> THIS LECTURE When describing the pharmacokinetic properties of a chemical, pharmacologists are often interested in LADME: Liberation - disintegration (for solid oral forms {breaking down into smaller particles}), dispersal and dissolution Absorption - How is the medication absorbed (through the skin, the intestine, the oral mucosa)? Distribution - How does it spread through the organism? Metabolism - Is the medication converted chemically inside the body, and into which substances. Are these active? Could they be toxic? Excretion - How is the medication eliminated (through the bile, urine, breath, skin)?

http://en.wikipedia.org/wiki/Pharmacology

PHARMACODYNAMICS See lecture “IN VITRO AND IN VIVO TESTING”

Kappa-elastin

Fast increase in intracellular free calcium afeter addition of elastin peptides (Kappa-elastin) or bacterial peptide (FMLP) to human polynuclear leucocytes. A: young persons (<45) ; b: aged persons (>65) ; c: aged persons with atherosclerosis. With ageing, a progressive uncoupling of the signaling pathway and aslower return to normal after calcium elevation can be observed.

+ AGE-RELATED CHANGES IN SIGNALING PATHWAYS

Pharmacokinetics, sometimes abbreviated as PK, (from Ancient Greek pharmakon "drug" and kinetikos "to do with motion"; see chemical kinetics) is a branch of pharmacology dedicated to the determination of the fate of substances administered externally to a living organism. The substances of interest include pharmaceutical agents, hormones, nutrients, and toxins. Pharmacokinetics is often studied in conjunction with pharmacodynamics. Pharmacokinetics includes the study of the mechanisms of absorption and distribution of an administered drug, the rate at which a drug action begins and the duration of the effect, the chemical changes of the substance in the body (e.g. by metabolic enzymes such as CYP or UGT enzymes) and the effects and routes of excretion of the metabolites of the drug.

http://en.wikipedia.org/wiki/Pharmacokinetics

Medication is said to have a narrow or wide therapeutic index or therapeutic window. This describes the ratio of desired effect to toxic effect. A compound with a narrow therapeutic index (close to one) exerts its desired effect at a dose close to its toxic dose. A compound with a wide therapeutic index (greater than five) exerts its desired effect at a dose substantially below its toxic dose. Those with a narrow margin are more difficult to dose and administer, and may require therapeutic drug monitoring (examples are warfarin, some antiepileptics, aminoglycoside antibiotics). Most anti-cancer drugs have a narrow therapeutic margin: toxic side-effects are almost always encountered at doses used to kill tumors.

http://en.wikipedia.org/wiki/Pharmacology

Divisions Clinical pharmacology The medical field of medication effects on humans and animals. Neuropharmacology Effects of medication on nervous system functioning. Psychopharmacology Effects of medication on the brain; observing changed behaviors of the body and read the effect of drugs on the brain. Pharmacogenetics Clinical testing of genetic variation that gives rise to differing response to drugs.

Pharmacogenomics Application of genomic technologies to new drug discovery and further characterization of older drugs. Pharmacoepidemiology Study of effects of drugs in large numbers of people. Toxicology Study of harmful or toxic effects of drugs. Theoretical Pharmacology Study of metrics in Pharmacology. Dosology How medicines are dosed. It also depends upon various factors like age, climate, weight, sex, and so on. Pharmacognosy A branch of pharmacology dealing especially with the composition, use, and development of medicinal substances of biological origin and especially medicinal substances obtained from plants also known as deriving medicines from plants

Behavioral Pharmacology Behavioral pharmacology, also referred to as psychopharmacology, is an interdisciplinary field which studies behavioral effects of psychoactive drugs. It incorporates approaches and techniques from neuropharmacology, animal behavior and behavioral neuroscience, and is interested in the behavioral and neurobiological mechanisms of action of psychoactive drugs. Another goal of behavioral pharmacology is to develop animal behavioral models to screen chemical compounds with therapeutic potentials. People in this field (called behavioral pharmacologists) typically use small animals (e.g. rodents) to study psychotherapeutic drugs such as antipsychotics, antidepressants and anxiolytics, and drugs of abuse such as nicotine, cocaine, methamphetamine, etc.

Environmental Pharmacology Environmental pharmacology is a new discipline. Focus is being given to understand Gene–environment interaction, drug-environment interaction and toxin-environment interaction. There is a close collaboration between the Environmental science and Medical community in addressing these issues. It is recognised that healthcare can itself be a cause of Environmental damage as well as its remediation. Human health and ecology is intimately related. Demand for more pharmaceutical products is destroying countless species of animals and plants, placing the public at risk. The entry of chemicals and drugs into the Aquatic ecosystem is a more serious concern today. In addition, the production of some Illegal drugs pollutes drinking water supply by releasing carcinogens. The pharmaceutical industry is encouraged to pay greater attention to the environmental impact of its products. More and more biodegradability of drugs are needed. It means environment friendly drugs could be designed. General standards for discharge of environment pollutants is implemented strictly and environmental impact assessment is checked frequently by health and other concerned regulators. Today, in Environmental Pharmacology, the topics which are covered includes Pharmacoenvironmentology and Ecopharmacology which is all about the study of Pharmaceuticals and personal care products in the environment.

The pharmacokinetic properties of a chemical, LADME: Liberation - disintegration (for solid oral forms {breaking down into smaller particles}), dispersal and dissolution Absorption - How is the medication absorbed (through the skin, the intestine, the oral mucosa)? Distribution - How does it spread through the organism? Metabolism - Is the medication converted chemically inside the body, and into which substances. Are these active? Could they be toxic? Excretion - How is the medication eliminated (through the bile, urine, breath, skin)?

1- Absorption/Administration Absorption is the process by which a drug is made available to the fluids of distribution of the body (e.g., blood, plasma, serum, aqueous humor, lymph, etc.). In the fasting state, most orally-administered drugs reach a maximum or "peak" blood concentration within 1-2 hours. Intravenous (IV) administration is the most rapid route of administration, with intra-nasal, smoking (inhalation), sublingual (under the tongue), intra-muscular (IM), subcutaneous (e.g., under the skin, SC or SQ), and percutaneous (through the skin) being the next most rapid. For a compound to reach a tissue, it usually must be taken into the bloodstream - often via mucous surfaces like the digestive tract (intestinal absorption) - before being taken up by the target cells. Factors such as poor compound solubility, gastric emptying time, intestinal transit time, chemical instability in the stomach, and inability to permeate the intestinal wall can all reduce the extent to which a drug is absorbed after oral administration. Absorption critically determines the compound's bioavailability. Drugs that absorb poorly when taken orally must be administered in some less desirable way, like intravenously or by inhalation (e.g. zanamivir).

http://en.wikipedia.org/wiki/ADME

Bioavailability In pharmacology, bioavailability (BA) is a subcategory of absorption and is used to describe the fraction of an administered dose of unchanged drug that reaches the systemic circulation, one of the principal pharmacokinetic properties of drugs. By definition, when a medication is administered intravenously, its bioavailability is 100 %. However, when a medication is administered via other routes (such as orally), its bioavailability generally decreases (due to incomplete absorption and first-pass metabolism) or may vary from patient to patient. Bioavailability is one of the essential tools in pharmacokinetics, as bioavailability must be considered when calculating dosages for non-intravenous routes of administration. For dietary supplements, herbs and other nutrients in which the route of administration is nearly always oral, bioavailability generally designates simply the quantity or fraction of the ingested dose that is absorbed. Bioavailability is defined slightly differently for drugs as opposed to dietary supplements primarily due to the method of administration and Food and Drug Administration regulations. Bioaccessibility is a concept related to bioavailability in the context of biodegradation and environmental pollution. A molecule (often a persistent organic pollutant) is said to be bioavailable when "[it] is available to cross an organism’s cellular membrane from the environment, if the organism has access to the chemical."

http://en.wikipedia.org/wiki/Bioavailability

In pharmacology In pharmacology, bioavailability is a measurement of the extent to which a drug reaches the systemic circulation. It is denoted by the letter f (or, if expressed in percent, by F).

Bioavailability is a ratio of areas under the curves

Factors influencing bioavailability The absolute bioavailability of a drug, when administered by an extravascular route, is usually less than one (i.e. F <100 %). Various physiological factors reduce the availability of drugs prior to their entry into the systemic circulation. Whether a drug is taken with or without food will also affect absorption, other drugs taken concurrently may alter absorption and first-pass metabolism, intestinal motility alters the dissolution of the drug and may affect the degree of chemical degradation of the drug by intestinal microflora. Disease states affecting liver metabolism or gastrointestinal function will also have an effect. Other factors may include, but are not limited to: - Physical properties of the drug (hydrophobicity, pKa, solubility) - The drug formulation (immediate release, excipients used, manufacturing methods, modified release – delayed release, extended release, sustained release, etc.) - Whether the formulation is administered in a fed or fasted state - Gastric emptying rate - Circadian differences - Interactions with other drugs/foods:

Interactions with other drugs (e.g. antacids, alcohol, nicotine) Interactions with other foods (e.g. grapefruit juice, pomello, cranberry juice, brassica vegetables)

- Transporters: Substrate of efflux transporters (e.g. P-glycoprotein) - Health of the GI tract - Enzyme induction/inhibition by other drugs/foods:

Enzyme induction (increased rate of metabolism), e.g. Phenytoin induces CYP1A2, CYP2C9, CYP2C19, and CYP3A4 Enzyme inhibition (decreased rate of metabolism), e.g. grapefruit juice inhibits CYP3A → higher nifedipine concentrations

- Individual variation in metabolic differences Age: In general, drugs are metabolized more slowly in fetal, neonatal, and geriatric populations Phenotypic differences, enterohepatic circulation, diet, gender

- Disease state e.g. hepatic insufficiency, poor renal function

Each of these factors may vary from patient to patient (inter-individual variation), and indeed in the same patient over time (intra-individual variation). In clinical trials, inter-individual variation is a critical measurement used to assess the bioavailability differences from patient to patient in order to ensure predictable dosing.

http://en.wikipedia.org/wiki/Bioavailability

Other way to say that : The RATE of absorption of orally-administered drugs and the subsequent appearance of the drug in the blood is dependent on the following factors: -The rates of disintegration and dissolution of the pill or capsule in the stomach or gastrointestinal (GI) tract,

-The solubility of the drug in stomach or intestinal fluids (the more soluble, the faster),

-The molecular charge on the drug molecule (charged substances are soluble, but don't pass through lipid (fat) soluble biologic membranes well),

-Aqueous (water) solubility vs. lipid (fat) solubility. Water-soluble drugs are soluble but don't pass through lipid-soluble biologic membranes well,

-The presence or absence of food in the stomach (food delays the absorption of some drugs and enhances the absorption of others),

- The presence of any concomitant medication(s) that can interfere with gastrointestinal (GI) motility, e.g., Reglan increases GI motility, Aluminum antacids slow, drugs like atropine or scopolamine used for ulcers or "queasy stomachs" slow GI motility keeping some drugs in the stomach slowing absorption, while drugs like Tagamet, Zantac and Prilosec (Pepcid-AC) decrease gastric acid production increasing the rate of gastric emptying and increasing the rate of absorption of some drugs.

http://www.doctorbenjamin.com/pharm/pharm.htm

Plasma concentration curves

Plasma drug concentration vs time after an IV dose

Drugs injected intravenously are removed from the plasma through two primary mechanisms:

(1) Distribution to body tissues and

(2) metabolism + excretion of the drugs. The resulting decrease of the drug's plasma concentration follows a

biphasic pattern (see figure).

Alpha phase: An initial phase of rapid decrease in plasma concentration. The decrease is primarily attribute

to drug distribution from the central compartment (circulation) into the peripheral compartments (body

tissues). This phase ends when an equilibrium of drug concentration is established between the central and

peripheral compartments.

Beta phase: A phase of gradual decrease in plasma concentration after the alpha phase. The decrease is

primarily attribute to drug metabolism and excretion.

Additional phases (gamma, delta, etc.) are sometimes seen.

2- Distribution Once a drug has been absorbed from the stomach and/or intestines (GI Tract) into the blood, it is circulated to some degree to all areas of the body to which there is blood flow. This is the process of distribution. The compound is carried to its effector site, most often via the bloodstream. From there, the compound may distribute into tissues and organs, usually to differing extents. After entry into the systemic circulation, either by intravascular injection or by absorption from any of the various extracellular sites, the drug is subjected to numerous distribution processes that tend to lower its plasma concentration. Organs with high blood flow e.g., brain, heart, liver, etc. are the first to accumulate drugs, while connective tissue and lesser perfused organs are the last. Distribution is defined as the reversible transfer of a drug between one compartment to another. Some factors affecting drug distribution include regional blood flow rates, molecular size, polarity and binding to serum proteins, forming a complex. Distribution can be a serious problem at some natural barriers like the blood-brain barrier.

Many drugs are bound to plasma proteins such as albumin. Since only drugs which are not bound are free to exert a pharmacologic effect, the ratio of "free" to "bound" drug is important in determining the onset and duration of action of drugs. Highly bound drugs are distributed less extensively throughout the body and are slower to act. By virtue of their high binding to plasma proteins, they also stay in the body for longer periods of time because the binding sites act as a sort of "reservoir" for the drug, releasing drug molecules slowly.

http://en.wikipedia.org/wiki/ADME

http://www.doctorbenjamin.com/pharm/pharm.htm

3- Metabolism Compounds begin to break down as soon as they enter the body. The majority of small-molecule drug metabolism is carried out in the liver by redox enzymes, termed cytochrome P450 enzymes. As metabolism occurs, the initial (parent) compound is converted to new compounds called metabolites. When metabolites are pharmacologically inert, metabolism deactivates the administered dose of parent drug and this usually reduces the effects on the body. Metabolites may also be pharmacologically active, sometimes more so than the parent drug. Drugs in the blood and tissues must be inactivated and excreted from the body. This process is initiated by altering the chemical structure of the drug in such a way as to promote its excretion. The transformation of the drug molecule into a chemically related substance that is more easily excreted from the body is called

metabolism, biotransformation or detoxification.

http://en.wikipedia.org/wiki/ADME Metabolism of homocystein

http://www.fda.gov/drugs/developmentapprovalprocess/developmentresources/druginteractionslabeling/ucm110632.htm

Metabolism - examples In the case of ethanol, the alcohol molecule is metabolized in the liver by the enzyme alcohol dehydrogenase, to acetaldehyde which causes dilatation of the blood vessels and, after accumulation, is responsible for the subsequent hangover which ensues. The acetaldehyde is subsequently metabolized by the enzyme aldehyde dehydrogenase to acetate, a substance very similar to acetic acid or vinegar. Therapeutic agents like antibiotics and drugs used for the treatment of high blood pressure, epilepsy (e.g., phenobarbital, Dilantin), pain (e.g., morphine, codeine), anxiety (e.g., Valium, Xanax) are also metabolized to chemically-related compounds called metabolites, which are then excreted in the urine. REMEMBER: Urine drug screens usually determine metabolites in urine, not the original "parent" drug which was ingested or taken. For example, if cocaine is snorted, smoked or injected, a urine drug screen will most often detect the cocaine metabolite benzoylecgonine in the urine, not cocaine itself. The same analogy applies to other drugs of abuse like: heroin, morphine, amphetamines, PCP (Angel Dust), barbiturates, marijuana, etc.

http://www.doctorbenjamin.com/pharm/pharm.htm

4- Excretion/Elimination Compounds and their metabolites need to be removed from the body via excretion, usually through the kidneys (urine) or in the feces. Unless excretion is complete, accumulation of foreign substances can adversely affect normal metabolism. There are three sites where drug excretion occurs: -the kidney is the most important site and it is where products are excreted through urine. - biliary excretion or fecal excretion is the process that initiates in the liver and passes through to the gut until the products are finally excreted along with waste products or feces. - the last method of excretion is through the lungs e.g. anesthetic gases.

Excretion of drugs by the kidney involves 3 main mechanisms: - Glomerular filtration of unbound drug. - Active secretion of (free & protein-bound) drug by transporters e.g. anions such as urate, penicillin, glucuronide, sulfate conjugates) or cations such as choline, histamine. - Filtrate 100-fold concentrated in tubules for a favorable concentration gradient so that it may be reabsorbed by passive diffusion and passed out through the urine.

http://en.wikipedia.org/wiki/ADME

Excretion Drugs can be excreted by various organs including the kidney and lungs, and found in many biological fluids like: bile, sweat, hair, breast milk, or tears. However, the most common fluid in which to look for drugs is the urine. In order to determine the rate of excretion of any drug from blood, one must first be certain that all the drug in the subject's GI tract has been absorbed. If not, calculation of a rate of excretion would be confounded be the ongoing absorption of more drug. Once all the drug has been absorbed, this is called the post-absorbtive, or distributive stage. At this time, serial (multiple) blood level determinations should show a decline with time. The slope of the log concentration-time graph is called the half-life (T1/2) and is indicative of the drug's half-life, or rate of excretion. The half-life represents the amount of time required to eliminate half of the drug from the body. The figure shows a typical plot of the drug's blood concentration on the verticle axis vs. time on the horizontal axis. Generally, it takes six half-lives to rid the body of 98% of a drug and 10 half-lives to completely eliminate the drug from the body. Using these mathematical relatonships allows pharmacologists to determine how often a therapeutic drug should be administered to a patient or toxicologists to determine a time interval within which one would test positive for drugs of abuse.

http://www.doctorbenjamin.com/pharm/pharm.htm

Class Effect on CNS* Representative Examples

Blood Positive Urine Positive

Amphetamine Stimulation Meth, Speed, Crystal Hrs-Days 1-2 Days

Barbiturates Depression Seconal, Nembutal Hrs-Days Hrs-Days

Cocaine Stimulation Crack, Free-Base, Salt ~6-10 hrs 1-2 Days

Narcotics Depression Heroin, Morphine, Codeine,

Hrs Hrs-Days

Methadone Hrs-Days 2-6 Days

Benzodiazepines Depression Librium, Valium Hrs-Days Days

Xanax, Halcion Hrs Days

Marijuana Depression Pot, Hashish Hrs-Days Days-Weeks

Phencyclidine Variable PCP, Angel Dust Days One Week

LSD Variable Acid Less than a Day 1-2 Days

Table I shows the approximate time intervals individuals will test positive in blood and urine for common drugs of abuse.

http://www.doctorbenjamin.com/pharm/pharm.htm

http://www.pharmacologyonline.org/PDF/excretion.pdf

http://www.pharmacologyonline.org/PDF/excretion.pdf

Factors that may increase half half-life (t ½ ): - Decreased metabolism – Liver disease. – Microsomal inhibitors. - Decreased clearance – Renal disease. – Congestive heart failure. - High binding of drugs. – Plasma proteins. – Tissue binding. - Enterohepatic recycling.

http://faculty.ksu.edu.sa/Hanan Hagar/Lectures 231/GENERAL PHARMACOLOGY (excretion).pdf

Biological Half-Life (t ½): T ½ is the time required to change the total amount of drug in the body by one-half. Is a measure of duration of action. Half-life α (t ½ α) is related to distribution ) is related to distribution phase. Half-life (t ½ β) is related to elimination phase and is generally longer than t ½ α.

http://faculty.ksu.edu.sa/Hanan Hagar/Lectures 231/GENERAL PHARMACOLOGY (excretion).pdf

Clearance: Units are L/h or L/h/kg Cltotal= total= ke . Vd Ke= is elimination rate constant Used for determination of maintenance doseUsed dose

http://faculty.ksu.edu.sa/Hanan Hagar/Lectures 231/GENERAL PHARMACOLOGY (excretion).pdf

Example of parmacological study: resveratrol (anti-oxydant, anti-inflammatory, anti-tumoral, life extension). Absorption and metabolism Radio-labeled trans-resveratrol has been used as a marker. After oral administration, it was found in the urine as a conjugated form and it was virtually undetectable in the plasma. Orally-administered resveratrol is absorbed at 70% in the intestine, which is notably elevated for a polyphenol. In some subjects, it appears as a trace in the plasma after 30 minutes, and it is the, degraded in the liver to form resveratrol-3-sulfate (or -4’- sulfate) or resveratrol-3-4’-disulfate (or -3,5-disulfate) and resveratrol-3-O-glucuronide (or -4’-O-glucuronide). Glucuronidation in 4’ is prefered. In 2003, Goldberg deducted that the benefit of non-conjugated resveratrol (found very active in vitro) was not so important in vivo. Investigation of the distribution of 14C-trans-resveratrol in mouse tissues can be done by using autoradiography. Vitrac et al. (2003) have observed that radioactivity concentration in the blood was relatively low and constant for the duration of the experiments (6h). After 3h, the radioactivity concentration is found in the duodenum, then (decreasing order) in kydneys, liver, lung, spleen, colon, heart, brain and testis. By using autoradiography, they showed that trans-resveratrol enters into the tissuese, especially in the liver where hepatocytes incorporate radioactivity. Taking into account the presence of resveratrol glucosides (piceid, astringin) in red wine and their possible degradation in the intestine, these experiments have concluded that a regular and moderated consumption of red wine can provide the body with a amount of resveratrol sufficient to exert a preventive anticancer action.

http://fr.wikipedia.org/wiki/Resvératrol

Example of parmacological study: resveratrol (anti-oxydant, anti-inflammatory, anti-tumoral, life extension).

Kidney

Tissues

Liver

Intestine wall

Intestine - colon

Deconjugation

5- Toxicity Sometimes, the potential or real toxicity of the compound is taken into account (ADME-Tox or ADMET). When the Liberation of the substance (from protective coating, or other excipients) is considered, we speak of LADME. Computational chemists try to predict the ADME-Tox qualities of compounds through methods like QSPR or QSAR. The route of administration critically influences ADME

http://en.wikipedia.org/wiki/ADME

http://en.wikipedia.org/wiki/Pharmacokinetics

http://en.wikipedia.org/wiki/Pharmacokinetics