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ATI Pharm 1
Pharmacokinetics and Routes of Administration
| Question | Answer |
|---|---|
| What are the phases of pharmacokinetics? (hint: 4) | 1) Absorption, 2) Distribution, 3) Metabolism, 4) Excretion |
| What is medication absorption? | Transmission of medications from location of administration to bloodstream |
| What are the different types of absorption? (hint: 7) | 1) Oral, 2) Sublingual/buccal, 3) Other mucous membranes (rectal, vaginal), 4) Inhalation via mouth/nose, 5) Intradermal, topical, 6) Subcutaneous/intramuscular, 7) Intravenous |
| Name the barriers to oral absorption. | Medications must pass thru layer of epithelial cells that line GI tract |
| What can affect oral absorption pattern? (hint: 5) | 1) stability and solubility of medication, 2) GI pH and emptying time, 3) presence of food in stomach and intestines, 4) other concurrent medications, 5) forms of medications (enteric-coated pills, liquids) |
| Name the barriers to sublingual/buccal absorption. | Swallowing before dissolution allows gastric pH to inactivate the medication. |
| Absorption pattern of sublingual/buccal administration. | Quick absorption systemically thru highly vascular mucous membranes |
| Name the barriers to other mucous membrane (rectal, vaginal) absorption. | Presence of stool in rectum or infectious material in vagina limits tissue contact. |
| Absorption pattern of other mucous membrane (rectal, vaginal) administration. | Easy absorption with both local and systemic effects |
| Name the barriers to inhalation via mouth/nose absorption. | Inspiratory effort |
| Absorption pattern of inhalation via mouth/nose administration. | Rapid absorption thru alveolar capillary networks |
| Name the barriers to intradermal/topical absorption. | Close proximity of epidermal cells. |
| Absorption pattern of intradermal/topical administration. (hint: 2) | 1) Slow, gradual absorption, 2) Effects primarily local, but systemic as well, especially with lipid-soluble medications passing thru subcutaneous fatty tissue |
| Name the barriers to subcutaneous/intramuscular absorption. | Capillary walls have large spaces between cells creating no significant barrier. |
| Absorption pattern of subcutaneous/intramuscular administration. (hint: 2) | 1) Solubility of medication in water (highly soluble=rapid absorption 10-30 min) (poorly soluble=slow absorption), 2) Blood perfusion at site of injection (high perfusion=rapid absorption) (low perfusion=slow absorption) |
| Name the barriers to intravenous absorption. (hint: bit of a trick question) | No barriers |
| Absorption pattern of intravenous administration. (hint: 2) | 1) Immediate: enters directly into blood, 2) Complete: reaches blood in its entirety |
| What is medication distribution? | Distribution is transportation of medications to sites of action by bodily fluids. |
| What are the 3 factors influencing distribution? | 1) Circulation, 2) Permeability of cell membrane, 3) Plasma protein binding |
| How does circulation affect distribution? | Conditions that inhibit blood flow or perfusion, such as peripheral vascular or cardiac disease, can delay medication distribution |
| How does permeability of cell membranes affect distribution? | Medication must pass thru tissues and membranes to reach target area. Medications that are lipid-soluble or have transport system can cross blood-brain barrier and placenta |
| How does plasma protein binding affect distribution? | Medications compete for protein binding sites within bloodstream, often albumin. Ability of medication to bind to protein affects how much medication leaves and travels to target tissues. Toxicity results when two medications compete for same binding site |
| What is another name for metabolism? | Biotransformation |
| What is medication metabolism and where does it occur? | Metabolism changes medications into less active or inactive forms by action of enzymes. Primarily occurs in liver, but also kidneys, lungs, intestines, and blood |
| Name 5 factors that influence the rate of medication metabolism. | 1) Age, 2) Increase in some medication-metabolizing enzymes, 3) First-pass effect, 4) Similar metabolic pathways, 5) Nutritional status |
| How does age affect medication metabolism? | Infants: limited medication-metabolizing capacity, Older adults: require smaller does due to possibility of accumulation in body (generally hepatic medication metabolism declines with age |
| How does an increase in medication-metabolizing enzymes affect medication metabolism? | When medication is metabolized sooner, more medication is needed to maintain therapeutic levels. |
| How does the first-pass effect change medication metabolism? | Liver inactivates some medications on their first pass thru liver, and thus they require nonenteral route (sublingual, IV) because of their high first-pass effect |
| How does similar metabolic pathways affect medication metabolism? | When same pathway metabolizes two medications, metabolism of one or both can be affected. Rate of metabolism can decrease for one or both leading to medication accumulation. |
| How does nutritional status affect medication metabolism? | Clients who are malnourished can be deficient in factors necessary to produce medication-metabolizing enzymes, causing impairment of medication metabolism |
| Names the 6 outcomes of metabolism. | 1) Increased renal excretion, 2) Inactivation of meds, 3) Increased therapeutic effect, 4) Activation of pro-medications into active, 5) Decreased toxicity-active becomes inactive, 6) Increased toxicity- inactive becomes active |
| What is medication excretion? | Elimination of medications from body, usually kidneys but also liver, lungs, intestines, exocrine glands |
| What often negatively affects medication excretion? What should be monitored? | Kidney dysfunction leads to increased duration and intensity of medication response. Important to monitor BUN and creatinine |
| Plasma levels minimum and above maximum. | Minimum: Minimum effective concentration (MEC), Above maximum: Toxic concentration |
| Therapeutic Index: Peak levels | Peak levels: highest plasma level when elimination=absorption |
| Therapeutic Index: Trough levels | Trough levels: Obtain blood sample immediately before next medication dose |
| Therapeutic Index: Plateau | Plateau: medication's concentration in plasma during series of doses |
| What is a half-life of a medication? | Half-life refers to the time for medication in body to drop by 50% |
| What two organs have the most affect on half-life? | Liver and kidney function. |
| Usually 4 half-lives to achieve steady state of serum concentration. (hint: equivalent equation) | medication intake = medication metabolism and excretion |
| Two facts about short half-life. | 1) Medication leaves the body quickly (4-8 hrs), 2) Short-dosing interval or minimum effective concentration (MEC) drops between doses |
| Three facts about long half-life. | 1) Medications leave body slowly (more than 24 hrs), with greater risk of accumulation and toxicity, 2) Give medications at longer intervals without loss of therapeutic effects, 3) Medications take long time to reach steady state |
| What is pharmacodynamics? | Pharmacodynamics describes interactions between medications and target cells, body systems, and organs to produce effects. |
| What are the 3 ways medications interact with cells? | Agonists, Antagonists, and Partial agonists |
| How do medications that are agonists interact with cells? Give one example. | Medications bind to or mimic receptor activity that endogenous compounds regulate. Ex: morphine, activates receptors that produce analgesia, sedation, constipation, etc. |
| How do medications that are antagonists interact with cells? Give one example. | Medications block usual receptor activity that endogenous compounds regulate or receptor activity of other medications. Ex: losartan, blocks angiotensin II receptors on blood vessels, which prevents vasoconstriction |
| How do medications that are partial agonists interact with cells? Give one example. | Act as agonists and antagonists with limited affinity for receptor sites. Ex: nalbuphine acts as antagonist at mu receptors and agonist at kappa receptors, causing analgesia with minimal respiratory depression at low doses |
| How many routes of medication administration are there? | There are a total of 15 routes of medication administration. |
| 1. Forms of oral/enteral medication administration. (hint: 6) | Tablets, capsules, liquids, suspensions, elixirs, lozenges |
| What is the most common route of medication administration? | Oral/enteral |
| When should you not administer medication by oral/enteral route? | Contraindications include vomiting, decreased GI motility, absence of gag reflex, difficulty swallowing, decreased level of consciousness |
| In what position should the patient be in when taking oral/enteral medication and why? | Patient should be in upright 90 degrees, to facilitate swallowing |
| What can be done to reduce irritation with certain oral/enteral medications? | Take with small amounts of food |
| Why not mix the oral/enteral medication with large amounts of food? | Patient may not be able to eat the whole amount, and you want them to get all the medication. |
| Interacting foods and oral/enteral medication. | Avoid administration with interacting foods/beverages, such as grapefruit juice |
| Generally, administer oral medications on empty stomach | 30 min-1 hr before meals, 2 hr after meals |
| Caution when crushing, cutting, and diluting oral/enteral medication | Follow manufacturer instructions: Ex: Only break or cut scored tablets, swallow enteric-coated or time-release medications whole |
| Benefit of liquid form of oral medication. | Easier to swallow |
| Advantages of oral/enteral medication administration. | Safe, inexpensive, easy and convenient |
| Disadvantages of oral/enteral medication administration. | Oral meds have highly variable absorption, inactivation in GI tract or by first-pass effect, patient must be cooperative and conscious, contraindications include nausea/vomiting |
| What is sublingual medication administration? | Put under the tongue to dissolve |
| What is buccal medication administration? | Put between cheek and gums |
| How is sublingual/buccal medication administration absorbed? | Directly into the bloodstream, bypassing the liver |
| Tips for sublingual/buccal medication administration. | Instruct patient to keep in place until fully dissolved, encourage no eating or drinking until fully dissolved |
| Tips for liquids/suspensions/elixirs medication administration. | Follow directions for dilution and shaking, pour into cup on flat surface so base of meniscus is at level of appropriate dose |
| How does transdermal medication administration work? | Medication in skin patch absorbed thru skin, producing systemic effects |
| Tips for transdermal medication administration. | Apply patches to ensure proper dosing, wash skin with soap and water and dry it, place patch on hairless area and rotate sites daily to prevent skin irritation |
| Advantages of topical medication administration. | Painless, limited adverse effects |
| Tips for topical medication administration. | Apply with glove, tongue blade, or cotton-tipped applicator, don't apply with bare hand |
| Where is instillation (drops, ointments, sprays) generally used on the body? | Eyes, ears, and nose |
| What position should the patient be in for instillation into the eyes? | Sitting upright or supine, head tilted back slightly looking at the ceiling |
| Exactly where in the eye should the instillation medication be placed? | Drop the medication into the center of the conjunctival sac (avoid placing directly on cornea) |
| Where should pressure be applied directly after instillation is administered to the eyes, for how long, and why? | Apply gentle pressure with finger and clean facial tissue to nasolacrimal duct for 30-60 seconds to prevent systemic absorption |
| How long should you wait before administering a second medication to the same eye? | 5 minutes |
| How should eye ointment be administered? | Apply thin ribbon on edge of lower eyelid from inner to outer canthus |
| What position should the patient be in for instillation into the ears? | Patient should be upright on on their side |
| For instillation of medication into the ears how should the ear canal be straightened for adults? | Pull auricle upward and outward |
| How should instillation into the ear be done? | Instill medication, then apply pressure to tragus if not too painful |
| If needed, where should cotton ball be placed following instillation into the ear? | Outermost part of ear canal, don't press it deep into canal |
| How long should patient remain side-lying after instillation into the ear? | 2-3 minutes |
| What technique should be used for instillation into the nose? | Medical aseptic technique |
| In what position should the patient be for instillation into the nose | Supine with head positioned to allow medication to enter appropriate nasal passage |
| What instructions should be given to patient following instillation into the nose? | Breathe through the mouth, stay in supine position, and don't blow nose for 5 minutes |
| What are 2 forms of inhalation medication administration? | Metered dose inhalers (MDI) and dry-powder inhalers (DPI) |
| Instructions for self-administration of MDI inhaler. | Remove cap, shake 5-6 times, hold mouthpiece at bottom, take deep breath and exhale, tilt head back and press inhaler while breathing in 3-5 sec, hold breath for 10 sec, breathe out "purse lips" |
| Instructions for self-administration of DPI inhaler. | DO NOT shake, exhale completely, take deep breath thru mouth, hold breath for 5-10 sec, exhale "purse lips", rinse mouth out with water or brush teeth to reduce risk of fungal infection, rinse in warm running water and dry completely before using again |
| What should be done when administering NG/gastrostomy tube medication? | Verify proper placement just before administration, flush with 15-30 mL of warm sterile water before and after administration to prevent clotting |
| Guidelines for NG/gastrostomy medication adminstration. | Use liquid forms when available, dissolve tablets/caps; DO NOT administer sublingual forms thru tubes; DO NOT crush extended/time-release, fluid-filled, enteric-coated medications; administer each med separately; DO NOT mix meds with enteral feedings |
| General guidelines for suppositories medication administration. | Follow directions for storage, wear gloves for procedure, remove wrapper and lubricate if necessary |
| Specific instructions for rectal suppository medication administration. | Insert just past internal sphincter, remain flat or left lateral for 5 min, absorption times vary with medication |
| In what position should the patient be for administration of rectal suppository medication? | Left lateral side or Sims' position. |
| What form does a rectal suppository medication take? | thin, bullet-shaped medication |
| In what position should the patient be for administration of vaginal suppository medication? | Position supine with knees bent and feet flat on bed, close to hips (modified lithotomy or dorsal recumbent position) |
| Specific instructions for vaginal suppository medication administration. | Insert along posterior wall of vagina (7.5-10 cm), remain supine for 5 minutes |
| What is the best location for administration of parenteral medication in infants 1 year or younger? | Vastus lateralis (outer thigh) |
| Preferred site for IM injections and injecting volumes exceeding 2 mL. | Ventrogluteal (fleshy part of hip) |
| Smaller muscle mass than ventrogluteal and can only accommodate up to 1 mL of fluid | Deltoid (back and outside of upper arm, shoulder) |
| Importance of needle and syringe size for parenteral medication administration. | Needle size and length should be appropriate for type of injection and patient's size, syringe size should be appropriate for volume of medication |
| Volumes of parenteral medication that should be given using a tuberculin syringe. | Solution volumes smaller than 0.5 mL |
| Two general thoughts about injection sites for parenteral medication. | Rotate injection sites to enhance medication absorption and document each site |
| Signs indicating inappropriate location for parenteral medication administration. | Don't use injection site that is edematous, inflamed, has moles, birthmarks, or scars |
| What should be monitored in patients after IV medication administration (and when)? | Immediately monitor clients for therapeutic and adverse effects |
| Important safety note for parenteral medication administration. | Discard all sharps (broken ampule bottles, needles) in leak- and puncture-proof containers |
| When is intradermal administration used? | For tuberculin testing or checking or medication or allergy sensitivities |
| How to administer intradermal medications. | Use small amount of solution in tuberculin syringe with fine-gauge needle in slightly pigmented, thin-skinned, hairless sites (inner mid-forearm or scapular area of back) at 10 to 15 degree angle; insert needle with bevel up, small bleb should appear |
| What should not be done after administration of an intradermal injection? | Do not massage the site |
| What types of medications are given by the subcutaneous route? | Small doses of nonirritating, water-soluble medications, such as insulin or heparin |
| What sizes of syringes should be used for subcutaneous medication administration? | 3/8 - 5/8 inch, 25 - 27 gauge needle, or 28 - 31 gauge insulin syringe (inject no more than 1.5 mL of solution) |
| What are the best sites for subcutaneous medication administration? | Adequate fat-pad size (abdomen, upper hips, lateral upper arms, thighs) |
| At what angle are subcutaneous medications administered for average-sized people? | Pinch skin and inject at 45 - 90 degrees |
| What types of medications are given by the intramuscular route? | Irritating medications, solutions in oils, and aqueous suspensions |
| Most common sites for intramuscular medication administration. | Ventrogluteal (fleshy part of hip), dorsogluteal (buttocks), deltoid (back and outside of upper arm, shoulder), vastus lateralis (outer thigh, for pediatric) |
| What sizes of syringes should be used for intramuscular medication administration? | 18 - 27 gauge (usually 22 - 27 gauge), 1 - 1.5 inch long. Solution volume usually 1 - 3 mL (divide larger volumes into two syringes and use two different sites) |
| At what angle are intramuscular medications administered? | Inject at 90 degrees. |
| Advantages of intramuscular medication administration. | For poorly soluble medications, for administering medications that have slow absorption for extended period of time (depot preparations) |
| Disadvantages of intramuscular medication administration. | More costly, inconvenient, can be pain with risk for local tissue damage and nerve damage, risk for infection at injection site |
| When is the Z-track technique used? | For all IM injections because it is less painful and prevents medications from leaking back into subcutaneous tissues, for medications that cause visible or permanent skin stains (ex: iron preparations) |
| What types of medication is administered by intravenous route? | Use for administering medications, fluids, and blood products. |
| What are the short term IV access called? | Catheters |
| What gauge of IV should generally be used for children, older adults and those who have medical issues or are stable postoperatively | 22 - 24 gauge |
| Which sites are preferable for intravenous medication administration? | Peripheral arm or hand preferable (ask patient for preferred site); for newborn - veins in head, lower legs, and feet; monitor immediately for therapeutic and adverse effects |
| Advantages of intravenous medication administration. | Rapid onset and absorption immediate providing immediate response, control over precise amount of medication administered, administration of large volume of fluid, dilutes irritating medications in free-flowing IV fluid |
| Disadvantages of intravenous medication administration. | More costly even than IM, inconvenient, absorption immediate so potentially dangerous if giving wrong dose or wrong medication, increase risk of infection or embolism, poor circulation can inhibit medication distribution |
| For what types of medication are epidurals used? | for IV opioid analgesia (ex: morphine or fentanyl) |
| How is epidural medication administered? | Clinician advances catheter thru needle into epidural space at level of 4th or 5th vertebra, infusion pump used for administration |
| What gauge IV should generally be used during a trauma? | 16-gauge |
| What gauge IV should generally be used for surgery or blood administration? | 18-gauge |
| What are the long term IV access called? | Infusion ports |
| At what angle are subcutaneous medications administered for obese people? | Pinch and inject at 90 degrees |
| For instillation of medication into the ears how should the ear canal be straightened for children? | Pull auricle downward and back |
Created by:
Sheena B