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Pharmacology Pharmacology :the science which study of the biochemical &physiological effects &source of drug &discovering & how uses Pharmacokinetics : the effects of the tissue on drugs which deal with absorption distribution metabolism &excretion Pharmacodynamics :the effects of the drugs on tissue (biochemical & physiological effects ) & action on body Mode of action :response of body to action Mechanism of action : effect of drug on the cell Drug : any substance which effect on living processes Uses of drug : 1_for treatment 2_for diagnosis 3_for multi vitamin 4_conterceptive Drug sources: 1_plants a _ alkaloids like atropine ,caffeine , nicotine b_ glycosides like digoxin , streptomycin c_ gums like acacia d_ oils like castor oil 2_ bacterial & molds as Pancillin , tetracyclines 3_animals as hormones (insulin) &anticoagulants as heparin 4_minerals as electrolytes (Na, K, Cl ) & Iron & Iodine 5_laboratories (synthetic) as barbiturate , sulfonamides& asprin Drug _receptor interaction *Receptor : protein molecule embedded in the cell membrane or cytoplasm of the cell * Ligand : molecule which binds (attaches) to a receptor & may be protein , hormone , drug , toxin, & neurotransmitter . Types of drugs _ receptors bonds : 1_Weak bond a _ H bond b _ Electrostatic bond} reversible association c _ vaderval bond } reversible association 2_ Strong bond as covalent bond } irreversible The action of drugs : *the drug induce its effect after binding with specific receptor (protein molecule in the cell ) * the number & rate of distribution of receptor depend on its type . The protein target of the drug : 1_Receptor : receptor binding drugs leading to alteration in biochemical and or biophysical activity of a cell eg * Receptor for histamine is called histamine receptor eg * Receptor for Ach is called muscurinic \ nicotine receptor 2_enzymes : drugs may bind with enzymes eg* Inhibition of dihydrofolate reductase enzyme by trimethoprim eg* Inhibition of Ach esterase enzyme by neostigmine 3_ Ion channels : drugs act in two ways a _ channels blocker : ( prevent passage of ion ) as local anesthetic by preventing Na⁺ & ca⁺⁺ blocker by diltiazem b _ channels modulator : by increase or decrease the entrance of ion 4 _ Structural protein eg: Tubulin is the receptor for colchicines in gout treatment . Types of receptor : 1_ Ion channel receptors (Iono tropic Receptor ): *the activity of these channels is regulated by the binding of aligand to the channel *Responsible for these regulation of the flow of ions a cross cell membrane * response to these receptors is very rapid & duration of few milli second eg: Ach _ nicotinic receptor stimulation by ach eg: GABA receptor stimulate by Benzodiazepam 2_ G _ protein _ coupled receptor ( metabotropic receptor ) : *consist of G _ protein coupled receptor * G _ protein having 3 subunit α_β_γ * Binding ligand to extracellular region of receptor , which activate G_ protein , so that GTP replaced GDP on α_ subunit * β&γ interaet with other ion channel * these effectors change the concentration of 2_ messenger which are responsible for further action in the cell * activation of adenyl cyclase by α _ GTP sub unit production of c_ AMP (2_massenger) * C_AMP regulate protein phosphorylation or case Ca⁺² release or other than cellular effect * Time scale is tens of seconds * eg: Nep , dopamine , serotonin & Ach muscurinic receptor 3_ Enzyme _ linked receptors : *Binding of ligand to an extracellular domin , activate or inhibits this cystolic enzyme activity * Upon binding , the conformational changes in the receptor * kinase enzyme convert from in active to active form * Binding ligand lead to kinase activity causes autophosphory lation of receptor → target molecule phosphorylate → cellular signals * time scale is minutes * eg : Insulin 4_ Intracellular receptor : *this type of receptor differ from others due to intracellular receptor *ligand must be diffuse into the cell to interact with receptor *ligand must be lipid soluble to move across cell membrane *the activated ligand _ receptor complex migrate to nucleus *complex typically dimerize *time scale is hours *eg : Glucocorticoids Drug _ receptor interaction Agonist : a drug that bind to a receptor of a cell & triggers a maximal response by the cell *An a gonist mimics the action of naturally occurring substance *eg : Ach + nicotinic receptor induce conformational changes in the receptors associated ion channel Partial agonist : molecule bind to receptors & induce sub maximal response even when in adequent amount of endogenous ligand are present *Partial agonist act as antagonist in presence of full agonist *eg: aripiprazole , buprenorphine Antagonists : it’s a molecule or drug that inhibit the action of anagonist but has no effect in the absence of the agonist Type of antagonism : 1_ receptor antagonist (pharmacologic antagonist ) a _ competitive A : Drug which block directly the binding site of agonist & divided into : Reveres able : eg Adrenaline agonist & propranolol antagonist Irreversible : The drug still bind to receptor even the drug concentration is completed eg: Phenoxybenzamine (antagonist ) at α receptor b _ Non competitive A : the drug not bind to the receptor but interfere with chemical events & stop the action of a gonist *eg: Diltiazem block calcium ion channel 2_ Non receptore antagonists : a _ chemical A : it inactive the agonist by modification it so result in active complex *Protamine is bind to heparin ( anticoagulant ) & prevent heparin activity by producing inert compound b _ physiologic A : The drug will produce the opposite function of other drug *Histamine produce dilation of blood vessels Adrenaline : Vaso constriction of blood vessels C _ Kinetic A :it happened antagonized the agonist in absorption or distribution or metabolism or excretion *eg: Diuretic increase the elimination of asprin eg: Charcoal (activated ) decrease absorption Potency : the concentration ( amount of drug ) which induce 50% of its maximal response *potent drug as morphine which give larger response at low concentration while the lower potent drug like acetylsalicylic acid give small response at low concentration *Potency depend on Affinity & Efficacy Efficacy : is the maximal therapeutic response produce by the drug *furosemide eliminate much salt & water than chlorothiazide Furosemide is greater efficacy than chlorothiazide Drug interaction : *Additive effect : the summation of effects which greater than separately effect eg: Paracetamol + codine . (2+2)= 4 *Potentiation : the effect after combination is more than the summation of their effect. (2+2)=6 *eg:Probancid retards the excretion of pencillin . * So pencillin persists longer when taken with it . * Synergistic effect : the effect after combination is more greater than the summation of their effect (2+2) = 10 Eg: phenobarbiton + Ethanol . *Antgonism : There is minimal or no effect result in the combination of their effect . (2+2)=0 or 1