PHARMACODYNAMICS Pharmacology Lecture Pharmacokinetics (PK) Pharmacodynamics (PD) Deals with the fate of the drug in the body – processes of Absorption, Distribution Metabolism Excretion …“ADME“ deals with the mechanism of action (e.g. receptor sites, molecular level of action..) „What the body makes with the drug“ „How does it work“ PHARMACOLOGY Pharmacokinetics Pharmacodynamics (how drugs work on the body) ̶ The action of a drug on the body, including receptor interactions, dose-response phenomena, and mechanisms of therapeutic and toxic action ̶ Main targets – cellular, molecular, genetic level… • Therapeutic effects • Adverse effects History of the Pharmacology Founders of specific drug effects - physiologist Newport Langley (1852–1925) and immunologist Paul Ehrlich (1854 – 1915). ̶ 1905 - John Newport Langley – pharmacology of vegetative nervous system and hormonal regulations (nicotin as receptive substance) ̶ 1906 – Paul Ehrlich – salvarsan - selective binding to the „chemoreceptros“ Mechanism of drug actions non-specificspecific Receptor non-receptor I. Non-specific drug effects …through by the general physical-chemical properties of substances - no specific chemical and structural configuration of drugs is needed - influencing pH - oxidating and reducing agents - protein precipitation - adsorbents / detergents - chelating agents a. based on osmotic properties  e.g. salinic laxatives (magnesium sulphate, lactulosa)  osmotic diuretics (mannitol) b. influencing acid-base balance  Antacids ̶ aluminium hydroxide ̶ magnesium carbonate ̶ calcium carbonate ̶ sodium bicarbonate  pH modifiers (blood, urine) - Sodium bicarbonate, ammonium chloride c. based on oxido – reducing properties  e.g. 3% hydrogen peroxide, boric acid, fenols  chlorhexidine act as antiseptics d. chelates (chelating agents)  ethylenediaminetetraacetic acid (EDTA) is a chelating agent, it can form bonds with a metal ion  dexrazoxane - a cyclic analog of EDTA administered with anthracyclines to prevent cardiotoxicity → Fe2 + ions) II. Specific drug effects effect depends on the specific molecules configuration  most drugs act (bind) on receptors  in or on cells  form tight bonds with the ligand  exacting requirements (size, shape, stereospecificity) ….on ion channels or carriers Specific drug effects many drugs inhibit enzymes ̶ A very common mode of action of many drugs  in the patient (ACE inhibitors)  in microbes (sulfas, penicillins)  in cancer cells (5-FU, 6-MP)  some drugs bind to:  proteins (in patient, or microbes)  DNA (cyclophosphamide)  microtubules (vincristine) A. RECEPTORS B. ION CHANNELS C. ENZYMES D. CARRIERS Agonist Antagonist Direct Signal Transduction No effect Endogenous mediator blocked Ion channels Open/closed Enzymes Activation/inhibition n channel modulation DNA transcription Blockers Modulators Flow is blocked Increasing or decreasing probability of opening Inhibitor False substrate Prodrug Reaction is inhibited Abnormal metabolites Active substance normal transport Inhibitor Transport is blocked Rang and Dale Pharmacology, 2017 A. Receptor – effector system = complex of processes extracelullar signal -------------> intracell. signal cascade---------> effector (own effect)  receptor = protein, which interacts ligands – involved in signal transduction  effector = enzyme, ionic channel etc. change in the activity leads to the effect of drug  ligand (signal molecule) = molecule able to bind to specific receptor – endogenous - neurotransmitters, hormones – exogenous - xenobiotics, drugs Receptor classification Localization  membrane  cytoplasm  organels  auto/heterore ceptors Transduction  metabotropic  ion. channels  kinase  DNA regulating Ligands  Achol  amines  AMA  peptides Receptor classification Lokalizace  membránové  cytoplazmat.  organelové  auto/heterore ceptory Transdukce  metabotropní  iont. kanály ligandové  kinázové  regulující DNA Ligandů  Achol  Aminy  AMK  peptidy Type 1 Receptors connected with ion channels Type 2 G-protein coupled receptor Type 3 Receptor tyrosin kinases Type 4 Intracellular (nuclear) receptors Place Membrane Membrane Membrane Intracellular Efector Ion channel Channel or enzyme Enzyme Gene transcription Binding direct G-protein direct DNA mediated Examples Nicotin-cholinergic receptor, GABA receptor Muscarin-cholinergic adrenoreceptors Inzulin, growth factor, cytokin receptor Steroids, thyroid hormon receptors Structure Oligomer composed by subunits surrounding center of the channel Monomer (or dimer) containing 7 transmembrane helical domains. Single transmembrane helical domain interconencted with extracelular kinase Monomer structure with separate receptor and DNA binding domain 4 main type of receptors Rang and Dale Pharmacology, 2012  Heptahelikální struktura.  Jedna intracelulární smyčka je delší a interaguje s G-proteinem  G-protein je membránový protein se 3 podjednotkami (a b g),  a-podjednotka má GTPázovu aktivitu  několik podtypů typů – Gs Gi Go Gq  Aktivace efektoru je ukončena, když navázaná GTP molekula je hydrolyzována, což umožní a-subjednotce rekombinaci s b g.  Příklady: muskarinový receptor, adrenoceptory, opioidní receptory, cannabinoidní receptory, histaminové a neuropeptidové receptory…. Receptory spřažené s G-proteinem (metabotropní) Type 1 Receptors connected with ion channels Type 2 G-protein coupled receptor Type 3 Receptor tyrosin kinases Type 4 Intracellular (nuclear) receptors Place Membrane Membrane Membrane Intracellular Efector Ion channel Channel or enzyme Enzyme Gene transcription Binding direct G-protein direct DNA mediated Examples Nicotin-cholinergic receptor, GABA receptor Muscarin-cholinergic adrenoreceptors Opioid receptors Inzulin, growth factor, cytokin receptor Steroids, thyroid hormon receptors Structure Oligomer composed by subunits surrounding center of the channel Monomer (or dimer) containing 7 transmembrane helical domains. Single transmembrane helical domain interconencted with extracelular kinase Monomer structure with separate receptor and DNA binding domain 4 main type of receptors Rang and Dale Pharmacology, 2012 NeurotransmiterExtracelular space 1 – innactive state - no interaction with Gs protein 2 – active receptor – structural change + interaction with Gs protein. Gs protein releasing GDP and bind GTP. 3 – a subunit Gs protein is released – activating of adenylylcyklase 4 while neurotransmiter is not present, receptor returning to steady state. GTP on a subunit is hydrolysed to GDP and adenylylcyklase is inactivated Receptor b g a GDP Cell membrane Gs protein + GDP Not active adenylyl cyklaseCytosol active adenylyl cyklase a a a b b b g g g GDP GTP GTP GTP GDP cAMP + PPi Pi ATP Rozpoznání chemických signálů membránovými receptory spřaženými s G-proteinem spouští zvýšení (nebo méně často snížení) aktivity adenylylcyklázy. (podle Lippincott´s Pharmacology, 2006) Not active adenylyl cyklase Not active Adenylyl cyklase Type 1 Receptors connected with ion channels Type 2 G-protein coupled receptor Type 3 Receptor tyrosin kinases Type 4 Intracellular (nuclear) receptors Place Membrane Membrane Membrane Intracellular Efector Ion channel Channel or enzyme Enzyme Gene transcription Binding direct G-protein direct DNA mediated Examples Nicotin-cholinergic receptor, GABA receptor Muscarin-cholinergic adrenoreceptors Inzulin, growth factor, cytokin receptor Steroids, thyroid hormon receptors Structure Oligomer composed by subunits surrounding center of the channel Monomer (or dimer) containing 7 transmembrane helical domains. Single transmembrane helical domain interconencted with extracelular kinase Monomer structure with separate receptor and DNA binding domain 4 main type of receptors Rang and Dale Pharmacology, 2012 Receptor Tyrosin Kinases (RTK)  RTKs mediate signaling by insulin and a variety of growth factors such as EGF, VEGF, PDGF..  Importance in the regulation of oncogenes and cell growth  Exists on the cell surface as monomers with the single transmembrane domain  When activated, the receptors dimerize and transfer phosphate to hydroxyl groups on tyrosines of target proteins  Time to response : minutes to hours Targeted therapy – receptor signaling pathways Cell membrane Ligand bindingl Receptor´s activation Proliferation Migration Tumor growth and matastases Survival Signal transduction Receptors with TKI activities Tyrosin- Kinases domain (TKI) Monoclonal antibodies Tyrozin-kinases inhibitors Type 1 Receptors connected with ion channels Type 2 G-protein coupled receptor Type 3 Receptor tyrosin kinases Type 4 Intracellular (nuclear) receptors Place Membrane Membrane Membrane Intracellular Efector Ion channel Channel or enzyme Enzyme Gene transcription Binding direct G-protein direct DNA mediated Examples Nicotin-cholinergic receptor, GABA receptor Muscarin-cholinergic adrenoreceptors Inzulin, growth factor, cytokin receptor Steroids, thyroid hormon receptors, vitamins Structure Oligomer composed by subunits surrounding center of the channel Monomer (or dimer) containing 7 transmembrane helical domains. Single transmembrane helical domain interconencted with extracelular kinase Monomer structure with separate receptor and DNA binding domain 4 main type of receptors Rang and Dale Pharmacology, 2012 Receptor – effector system ̶ Affinity  the ability of the ligand to bind to the receptor ̶ Instrinsic activity  ability to evoke an effect after binding to receptor ̶ !!!the presence of sufficient number of receptor for the induction of pharmacological effect is essential as well as sufficient amounts of receptor ligand!!! Ligand classification (intrinsic activity) AGONISTS Full agonist Partial agonist - IA = 1 - dualist - IA in a range from 0‹ to ›1 Ligand classification Antagonists  IA = 0  Blocks agonist binding to receptor Inverse agonist  IA = -1  Stabilizesthe receptor in the constitutive activity Relation between dose and effect Receptor-effector system Spectrum of ligands Antagonism competitive reverzible non-competitive irreverzible at the receptor level at the function level Antagonism Competitive  ligands compete for the same binding site   c of antagonist decreases agonist effect and inversely  the presence of antagonist incerases the amounts of agonist needed to evoke the effect Non-competitive  allosteric antagonism  irreverzible bounds   c of agonist does not interrupt the effect of antagonist DRC – linear curve – lineární zobrazení. Compound A Compound B EC50 EC50 is concetration of the compound which induce 50 % of max. effect [compound] 0 50 100 %max.effect (podle Lippincott´s Pharmacology, 2006) DRC – semilogaritmické zobrazení. EC50 Compound A compound B log [compound] 0 50 100 %max.effect Affinity of the compound can be compared by EC50, as lowerEC50 - so higher affinity. (podle Lippincott´s Pharmacology, 2006) DRC – semilogaritmic – lineární zobrazení. DRC ukazující rozdíly v afinitě a vnitřní aktivitě. (EC50 = koncentrace léčiva vedoucí k 50 % max. odpovědi) A higher affinity to B, same internal activity C lower affinity and lower internal activity compared to A a B. Comp. A Comp. B Comp. C Log drug concentration EC50 A EC50 B EC50 C 0 50 100 Biologicaleffect (podle Lippincott´s Pharmacology, 2006) Regulation of receptor function Receptor desensitization • reducing the sensitivity of the receptors after repeated agonist exposure • Tachyphylaxis – acute drug „tolerance“ – reduced sensitivity to the active substance evolving quickly (minutes) → distortion of the signal cascade – the reactivity of the organism returns to the original intensity after the elimination of the substance – Ex. of tachyphylaxis – nitrates administration, ephedrine • Tolerance – reduced sensitivity to the active substance, arising from the repeated administration of the drug (days – weeks) → down-regulation, internalization of the receptors – to achieve the original effect required increasingly higher doses of drug – the original reactivity of the organism returns to a certain period of time after discontinuation of the drug – Ex. of tolerance – opioids administration Regulation of receptor sensitivity and counts Hypersensitivity incerase of receptor sensitivity/counts after chronic anatagonist exposure Rebound phenomenom after discontinuation of long-term administered drugs return to its original state or ↑ intensity of the original condition (hypersensitivity of receptors to endogenous ligands → up- regulation) Example: chronic administration of β blockers Regulation of receptor sensitivity and counts B. Non-receptor mechanism of action Interaction with „non-receptor“ proteins ̶ 1. enzyme inhibition ̶ 2. block of ion channels ̶ 3. block of transporters „non-proteins“ ̶ binding to cellular components (ATB-ribosomes, hydroxyapatit, tubulin etc.) 1. Enzyme inhibition Competitive or non-competitive enzyme inhibitors reversible  acetylcholinesteraze– physostigmine  phosphodiesteraze – methylxantine irreversible:  Cyklooxygenaze – ASA (aspirin)  MAO-B – selegilin  aldehyddehydrogenaze– disulfiram 2. Ion channels  Calcium channel blockers (nifedipin, isradipin…)  Potassium channel blockers (flupirtin – selective neuronal potassium channel modulator, oral antidiabetics…)  Natrium channel blockers – local anesthetics 3. “Carriers“  Proton pump inhibitors (PPIs) – omeprazol  Na+/K+ ATPasa inhibitors – digoxin Next lecture 29.10.2019 - Adverse effects, pharmacovigilance Thank you for your attention