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Pharmacology • The study of drugs and their actions
Reasons For Medication Use • Diagnose • Treatment • Curative • Lesson pain • Prevent a disease or condition
Where Do Drugs Come From? • Plants • Animals • Minerals • Laboratory Chemical combinations • Biotechnology Genetics
Pharmacokinetics Definition: • The process a drug goes through upon entering the body • It involves the processes of absorption, distribution, biotransformation (metabolism - liver), and excretion
Pharmacokinetics Absorption: For a drug to work , it must be absorbed. It is absorbed at the site where it is given. Once a drug reaches the capillaries, it is taken into the bloodstream. The rate of absorption varies depending on the type of drug, amount of the drug, route, and the patient.
Pharmacokinetics Continued Distribution: How the drug gets to its target once it is in the bloodstream. Involves circulation of the blood. Targets are cells in tissue or organs.
Pharmacokinetics Metabolism: How a drug is broken down for excretion. Products of breakdown are called metabolites. Metabolites are rendered small, inactive or less active before excretion occurs. Metabolism usually occurs in the liver, however can occur in the kidneys, lungs, blood plasma, or intestinal mucosa.
Pharmacokinetics Excretion: A drug continues to have an action until it is excreted by the body. Kidneys generally are the excretory route. Drugs can be excreted by saliva, sweat, exhalation, breast milk, or feces (poop).
Pharmacodynamics Definition: Is the study of how a drug acts on targeted cells.
Pharmacodynamics Types of Drug Actions: • Inhibitive or destructive • Protection • Supplementation • Replacement • Physiologic function (increase or decrease)
Pharmacodynamics Drug Effect or Action Theories: • Agonists-Drug binds to a special receptor on a target cell and produce the desired effect. • Antagonists-Drug binds with a special receptor on a target cell and prevent or inhibit a response. • Non-specific-Neither agonists or antagonists. These drugs gather on a cell’s membrane or go through it and interfere with actual cell function
Pharmacodynamics Timing of Drug Effects: • Onset- time from when a drug is given (administered) to when effects first occur (or are noticed) • Peak Effect- whena drug is at itsmaximum (peak) effect • Duration- time from when drug effects begin to when they stop
Buccal(*topical) - cheek IM Inhalation Intra-articular Intradermal/dermal Intrathecal – anywhere CSF flows *Topical =‘s any epithelial lined surface. Tongue, rectally, cheek, vagina etc IV Intracardiac po/PO SC/subq - Subcuticular(within epidermis) vs subcutaneous(below skin) sublingual (topical) – under the tongue *topical Routes of Drug Administration
Drug Preparations • Forms of: • solid • semi-solid • liquid • gas/vapors
Topical cream gtts (ear) - drops ung (ointment) PO cap gtts (oral/infants) soln/sol - A solution is a mixture in which other substances are dissolved. Susp- A suspension is a mixture of liquids with particles of a solid which may not dissolve in the liquid. Tab - tablet Abbreviations for PO or Topical Administration
Abbreviations: bid h/hr prn/PRN q qd qh q2h qid tid stat Frequency of Drugs
AD (right ear) AS AU OD (right eye) OS OU os aa (of each) ad (towards) RX c (line over it) dc/DC KVO/TKO npo/NPO per Administration Abbreviations
Nomenclature (Naming) of Drugs • Chemical name: chemical make-up of a drug • Generic name: nonproprietary name given to a drug by the developer of a drug (acetaminophen, ibuprofen, diphenhydramine) • Trade or Brand name: Proprietary or patented name of the manufacturer of the drug (Tylenol, Motrin & Advil, Benedryl). Manufacturing processes may differ slightly.
Legal Implications(Federal) • Pure Food and Drug Act -Standards for US marketing • Federal Food, Drug, and Cosmetic Act -Regulations -FDA approval • Controlled Substances Act -Established DEA -Schedule of Controlled Substances: C-I - Marijuana C-IV – Phenobarbital (treat seizures) C-II - Cocaine C-V – antidiarrheal (low abuse rate) C-III – anabolic steroids The lower the # the higher the addiction/abuse potential
Legal Implications(State) • Regulate practice acts for ordering, prescribing, and administration of medications • As a surgical technologist, we act as an extension of the physician handling drugs under their supervision
Legal Implications(Local) • May have specific guidelines for medication administration in the institution you are employed in
Metric System • Meter = length • Liter = capacity • Gram = weight
Metric Prefixes • Micro-one-millionth; 0.000001 • Milli-one-thousandth; 0.001 • Centi-one-hundredth; 0.01 • Deci-one-tenth; 0.1 • Unit-one;1.0 • Deka-ten;10.0 • Hecto-one-hundred;100.0 • Kilo-one thousand;1000.0
Weight (gram) 1 gram=1000 milligrams 1 kilogram=1000 grams 1 ounce=30 grams Capacity (liter) 1 liter=1000 milliliters 1000 liters=1 kiloliter 1 liter=1.06 quarts 1 quart=0.946 liters 1 milliliter weighs 1 gram 1 cubic centimeter (cc) and 1 milliliter (ml) are equal/same 1 liter=1000ml or cc 1 fl. oz.=30ml or cc 1 fl. dram=0.125fl. oz. or 4ml or cc 1 gallon=3.8 liters Metric Equivalents
Metric Equivalents • Length (meter) • 1 meter=1000mm=100cm=1.094 yd • 1 yard=3 ft.=36 in.=0.9144 meters • 1 in.=2.54 cm=25.4mm • 1 micron (micrometer)=0.001mm=0.000001 meter
Gram-gm Milligram-mg Kilogram-kg Liter-L Milliliter-ml Cubic centimeter-cc Meter-M Millimeter-mm Centimeter-cm Metric Abbreviations
Temperature Measuring • Fahrenheit (F) Water freezes at 32° Water boils at 212° • Celsius (C) (centigrade) Water freezes at 0° Water boils at 100°
Converting C° to F° or F° to C° • Fahrenheit to Celsius • 5/9 (F°-32) = C° ( or F -32 x 5 divided by 9 = C) • Celsius to Fahrenheit • 9/5 (C°)+32 = F° (or C x 9 divided by 5 + 32 =‘s F)
Dosage Calculations • Formula: • D (desired dose) x Q (quantity ofdose on hand) H (dose on hand) =‘s X X = Amount to give/needed • Example: Give 80mg of a drug from a 30ml stock bottle labeled “100mg per 1ml
I know: 1ml=100mg Need to give 80mg • I do not know: Fraction of ml that=80mg • Common sense: If 1 ml of the solution = 100mg of the drug, then the amount given must be less than 1ml.
Formula: D x Q = amt to give H • Solution: 80mg x 1ml=0.8 ml of sol. 100mg • Proof: 80÷100=0.8 0.8x1=0.8
Standard Dilution Equations • C1 x V1 = C2 x V2 • C = concentration in % • V = volume • Problem: Dr. needs 60 ml of ½% contrast media. How much NACL and how much media do you need to make the required amount when you have 60 ml’s of 1% media?
First we must convert the % to decimals • 1/2% = 0.5 • 1 divided by 2 = 0.5 • You always do this when converting percentages to decimals
C1=1/2%=0.5 Concentration 1 (asked for) • C2=1% = Concentration 2 (given) • V1=60ml Volume 1 (asked for) • V2=x (? volume of saline)
Formula: C1 x V1 = C2 x V2 • 0.5 x 60 =1 x x • 30 = x • So, You add x=30 ml’s of pure saline • Need 60mlof 1% – 30ml’s = 30ml’s of 1% dye solution and add 30ml’s saline to get 60ml of 0.5% dye solution
No Total Amount Asked For? • Procedure calls for 1/2% contrast media. I have 60 ml’s of 1% contrast media. How much NACL do I need to add to the mix to get a ½% solution? • 60ml’s of 1% contrast media needs to have 60 ml’s of NACL added to the mix to dilute the mixture to ½%. We will be left with 120 ml’s of 1/2 % solution. • The difference is this question and the one above is that the one above calls for 60 ml's as a final amount on your field. Therefore we need 30 ml’s of contrast media and 30 ml’s of NACL to equal 60 ml’s for that question. This question does not specify the ending total amount.
Standard Dilution Equation • Doctor wants ½% lidocaine. You have 25ml of 1% Lidocaine. How do you dilute it to the proper strength? • C1 (asked) x V1 (given) = C2 (given) x V2 (?) • ½% x 25 = 1% x x • 12.5= x • 25ml lidocaine – 12.5mlof 1% lidocaine = 12.5ml lidocaine = 12.5ml saline = ½% or 0.5% lidocaine
Calculating mg Dose per kg Body Weight • Normal dose of propofol (an induction drug used by anesthesia) is 2 mg per kg for an adult • Find initial dose for an adult weighing 150lbs • Convert lbs. to kg (2.2 lbs. = 1kg) • 150lbs. ÷ 2.2lbs. = 68kg • 68kg x 2mg = 136mg
Calculating Child Dosages • Clark’s Rule: Standard adult weight=150lbs • Problem: If an adult receives 75mg of Demerol, what would be an appropriate dose for a child weighing 30lbs? • Adult dose=75mg • Child weighs 30lbs. • Clark’s rule Standard adult weight = 150lbs. • Common sense: child is smaller, dose will be less than 75mg
Formula: Child’s weight x Adult dose = Child’s dose Adult weight • Solution: • 30lbs. x 75mg = 15mg of Demerol 150lbs
The order calls for a dosage of 20 mg’s of a medication that comes in a concentrate of 4 mg’s per ml. How many ml’s do I need? • 20 mg x 4mg ______ _____ =’s cross multiply. 20mg x 1ml = 4mg x’s x ml • X ml 1ml • 4x = 20 divide both sides by 4 • X = 5mls
What % of NACL is preset in a 2:3 mixture of tincture and NACL? Hint: There are 5 total parts of the mixture. • Total parts =’s 5 • So 2/5’s is tincture = ( 2 divided by 5 = 0.4) 40% • 3/5’s is NACL = ( 3 divided by 5 = 0.6) 60% • #41. You have a 4:5:1 solution of water, alcohol, and tincture. What % of the solution does each ingredient represent? • 4 = water or 4/10 or 40% • 5 =’s alcohol or 5/10’s or 50% • 1 =’s tincture or 1/10 or 10%
Mixing Medications • Do not mix drugs unless you know for certain that they are compatible together • If a compatibility is questioned direct the question to the pharmacist to be certain before mixing • Mixing drugs that are incompatible can result in decreased or increased efficacy, precipitates/crystallization of the drugs which could cause embolization of the drug in the patient, or death • Institutional pharmacies keep a compatibility chart in the pharmacy/Some ORs may have them in the room
Pharmacokinetics Pharmacodynamics Actions/Effects Abbreviations Nomenclature Legal implications Metric System Conversions/ Mathematics Dosage Calculations Mixing Medications Summary