Slide 1The Therapeutic Objective of Drug Therapy:Drug ClassificationsDRUG NAMESWhy Do Patients Respond Differently to the Same Drug?Pharmacokinetics-impact of body on the drugAbsorptionRoutes of AdministrationDistributionDrug Movement at Capillary Bedsal Drug TransferProtein Binding of DrugsMetabolismExcretionSingle-dose Time CurveDrug Half-lifeEffect of Kidney Failure on Drug Half-lifePlateau or “Steady State”Drug Accumulation with Repeated DosesPHARMACODYNAMICSDose-response RelationshipSlide 23ReceptorsSlide 25Do you know where this is? (Crete in May)Drug interactionsOther interactionsADVERSE DRUG REACTIONSADRIdentifying ADRBOXED WARNINGSFDA Drug Categories for Pregnancy:Medication ErrorsMedications errorsISMPPatient ComplianceSome Commonly Used AbbreviationsSpecial populations:Module 1: Introduction to PharmacotherapeuticsUNCW School of Nursing1The Therapeutic Objective of Drug Therapy:To provide maximum benefit with minimum harm.Because no drug is ideal…Each health care team member must exercise care and skill to achieve objectiveUse reputable source of information2Drug ClassificationsOver-the-counter (OTC)MedicationSupplementsHerbalsPrescriptionNon-controlled-ViagraControlled substances-morphineSchedules I, II, III, IV, VRange from high potential for abuse (Schedule I) to low potential for abuse (Schedule V)Schedule I and II cannot be called in / must be written in person due to abuseInvestigational 3DRUG NAMESPurposes:To communicate about medications (written and verbal)To accurately identify containers of medicationsThree names:Chemical – same all over (safest to use)Generic – changes from country to country Trade (Brand) – most used4Why Do Patients Respond Differently to the Same Drug?Administration errorsBy the care providerBy the patient (compliance)PharmacokineticsPharmacodynamicsIndividual characteristics (body weight, age, gender)Pathophysiology (kidney/ liver disease)TolerancePlacebo effectGenetics (idiosyncratic reactions)Drug/food interactionsNutritional statusBioavailability5Pharmacokinetics-impact of body on the drug6AbsorptionThe movement of a drug from site of administration to the blood. Rate of absorption determines how soon effects will beginAmount of absorption determines how intense effects will beBioavailability: ability of a drug to be absorbedInvolves factors such as tablet disintegration, enteric coatings, sustained-release preparations etc.Factors that affect absorption:Administration routeDissolution, blood flow, lipid solubility , surface area7Routes of AdministrationEnteral: “via the gut” Oral (PO)-low cost, easy to use, interactionsRectal (PR)- safe route with decreased LOC, uncomfortableParenteral: “outside the gut”Intravenous (IV)-fast, large volume, increased infectionIntramuscular (IM)-small volume, painful Subcutaneous (SC)-little volumeOthers: topical, vaginal, intranasal, inhaled Note: usually only injection are referred to as parenteral8DistributionDefinition: the movement of drugs in bloodstream throughout body to site of action.Mostly determined by amount of blood flow to tissuesSome unique situations that affect distribution:Blood-brain barrier: makes it difficult for drugs to reach CNS. (This can be good and bad)Placenta: fetus receives drugs taken by mother. No barrier to distribution. (nursing mothers and their babies)Protein-bound drugs: do not pass through capillary walls (Albumin is an important blood protein that many drugs bind to)9Drug Movement at Capillary Beds1011Drug movement across blood brain barrieral Drug Transfer12Placental Drug TransferProtein Binding of Drugs13MetabolismDefinition: “the enzymatic alteration of drug structure”; biotransformation. Involves cytochrome P-450 system.Can be a source of interactions and toxicities.Liver is the most important organ for metabolismMonitor LFT (AST/LFT)Special considerations:Age- infants <1 yo and elderly have decreased ability to metabolize drugs due to immaturity and deterioration of liver, respectivelySome drugs can increase metabolism of other drugs (example-Phenobarbital or rifampin) while others decrease metabolism of drugs (erythromycin)First-pass effect- ability of the liver to inactivate oral drugs after being absorbed (lidocaine, nitroglycerin)Usually administered parenterally or topically14ExcretionDefinition: “the removal of drugs from the body”Kidney is the most important organ for excretionMonitor BUN; Creatinine, GFR, UOPSpecial considerations:Age:Elderly have decreased excretion due to deterioration of kidney functionNewborns have decreased excretion due to immaturity of kidney function; normal renal function occurs several months after birth15Single-dose Time Curve16Drug Half-life Definition: The time required for the amount of drug in the body to decrease by 50%Mainly affected by kidney functionDetermines drug dosing interval: The time between each drug doseDrugs with short T1/2 , drug interval is short; dose more oftenDrugs with a long T1/2, drug interval is long; dose less often17Effect of Kidney Failure on Drug Half-life18Plateau or “Steady State”Definition: with repeated dosing of a drug, plateau is reached when the amount of drug eliminated between doses equals the amount of drug administered.With repeated dosing, plateau is reached in approximately 4-5 half-lives.As long as dose remains the same, time to plateau is independent of dosage sizeWhen a drug is discontinued, most of the drug will approach a “zero” drug level in approximately 4-5 half-lives.19Drug Accumulation with Repeated Doses20PHARMACODYNAMICSDefinition: the study of the biochemical and physiologic effects of drugs on the body or what drugs do to the body and how Some key concepts:Dose-response relationshipsMaximal efficacyRelative potencyReceptorsTherapeutic index (TI)21Dose-response Relationship22Efficacy-largest effect of drug Potency- amount of drug to get effect23ReceptorsWhat are they? A molecule in a cell that drugs bind to produce an effect. Most drugs interact with multiple receptors on different types of cells. This explains why almost all drugs have associated side effects.Types of drug-receptor relationships:Agonist- a drug that activates a receptor