Applied mathematics article

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Absorption is the transfer o. Absorption of Drugs Absorption is the transfer of a drug from its site applied mathematics article administration to the blood stream Most of drugs are absorbed by the way of passive transport Intravenous administration has no absorption Fraction of administered dose and rate of absorption are important Drug properties:.

Factors affecting absorption Drug properties: lipid solubility, molecular weight, and polarity etc Blood flow to the absorption site Total surface area available for absorption Contact time at the absorption surface Affinity with special tissue Routes of Administration Prezista (Darunavir)- FDA Route of admi. As a Result, the concentration of drug in the systemic circulation will be reduced.

Bioavailability Bioavailability refers to the rate and extent of absorption of a drug from dosage form as determined by its concentration-time curve in blood or by its excretion in urine.

It is a measure 9oo the fraction (F) of administered dose of a drug that reaches the systemic circulation in the unchanged form Bioavailability of drug injected i.

MTC MEC It is the passage of drug. The applied mathematics article of distribution of drug depends on its lipid solubility, ionization at physiological pH (dependent on pKa), extent of binding to plasma and tissue proteins and differences in regional blood flow, disease like CHF, uremia, cirrhosis Movement of drug - until equilibration between unbound drug in plasma and tissue fluids Definition: Apparent Vol.

Blood brain barrier (BBB) : includes the capillary endothelial cells (which have tight junctions and lack large intracellular pores) and an investment of glial from amoxil, over the applied mathematics article. A applied mathematics article barrier is loctated in the choroid plexus Brain and CSF Penetration BBB is lipoidal.

BBB is lipoidal and limits the entry of non-lipid soluble drugs (amikacin, gentamicin, neostigmine etc. This is used latter in parkinsonism. Only lipid soluble Drugs can applied mathematics article. Plasma Protein Binding Plasma protein binding (PPB): Most drugs possess physicochemical affinity for plasma proteins. Increasing concentration of drug can progressively saturate the binding sites The clinical significant implications of PPB are: a) Highly PPB drugs are largely restricted to the vascular compartment and tend to have lower Vd.

Drugs may also accumulate in specifi. Tissue storage Drugs may also accumulate in specific organs or get bound to specific tissue constituents, e. Biotransformation Metabolism of Drugs Chemical alteration of. Biotransformation is required for protection of body from toxic metabolites Active drug and its me.

In addition to liver, applied mathematics article isoforms are expressed in intestine (responsible for first pass metabolism at this site) and kidney too Applied mathematics article of CYP 3A4 by erythromycin, clarithromycin, ketoconzole, itraconazole, verapamil, diltiazem and a constituent of grape fruit juice is responsible applied mathematics article unwanted interaction with terfenadine and astemizole Rifampicin, phenytoin, carbmazepine, phenobarbital are inducers of the CYP 3A4 applied mathematics article. Phase I - Reduction This reaction is conversed of oxidation and involves CYP 450 enzymes working in the opposite direction.

Examples - Chloramphenicol, levodopa, halothane and warfarin Levodopa (DOPA) Dopamine DOPA-decarboxylase This is cleavage of drug molec. Phase I - Hydrolysis This is cleavage of drug molecule by taking up of a molecule of water. Similarly amides and polypeptides are hydrolyzed by amidase and peptidases. Hydrolysis occurs in liver, intestines, plasma and other tissues.

Decyclization: is opening up of ring structure of the cyclic molecule, e. Phase II metabolism Conjugation of the drug or its phase I metabolite with an endogenous substrate - polar highly ionized organic acid to be excreted applied mathematics article urine or bile - high energy requirements Glucoronide conjugation - most important synthetic reaction Compounds with hydroxyl or carboxylic acid group are easily conjugated with glucoronic acid - derived from glucose Examples: Chloramphenicol, aspirin, morphine, metroniazole, bilirubin, thyroxine Drug glucuronides, excreted in bile, can be hydrolyzed in the gut by bacteria, producing beta-glucoronidase - liberated drug is reabsorbed and undergoes the same fate - enterohepatic recirculation (e.

Acetylation: Compounds having amino or hydrazine residues are conjugated with the help of acetyl CoA, e. Methionine and cysteine act as methyl donors. Examples: adrenaline, histamine, nicotinic acid. Factors affecting Biotransformation Factors affecting biotransformation C oncurrent use of drugs: Induction and inhibition G enetic polymorphism P ollutant exposure from environment or industry P athological status A ge One drug can inhibit metabolism o.

Excretion Excretion is a transport proced. Organs of Excretion Excretion is a transport procedure which the prototype drug (or parent drug) or other metabolic products are excreted through excretion organ or secretion organ Hydrophilic compounds can be easily excreted. Routes of drug excretion Kidney Biliary excretion Sweat and saliva Milk Pulmonary Drugs can applied mathematics article excreted in 66.

Energy dependent active transport. Renal Excretion Acidic urine alkaline drugs eliminated acid drugs reabsorbed Alkaline urine - acid drugs eliminated - alkaline drugs absorbed Pharmacokinetics - F, V and. Kinetics of Elimination First Order Kinetics applied mathematics article Rate of elimination is directly proportional to drug concentration, CL remaining constant Constant encyclopedia for herbal medicine of drug is eliminated per applied mathematics article time Applied mathematics article Order kinetics (linear): The rate of elimination remains constant irrespective of drug concentration CL decreases with increase in concentration Alcohol, theophyline, tolbutmide etc.

Kinetics of Elimination Zero Order 1st Order applied mathematics article. Time Defined as time taken for its plas. Plasma half-life 1 half-life …………. Target Level Strategy Low safety margin drugs (anticonvulsants, antidepressants, Lithium, Theophylline etc. You just clipped your first slide.



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