what will affect absorption of medications?

• Affected by drug form, route, GI mucosa and motility, food and other drugs, changes in liver
• The same drug—given IV—bypasses the liver, preventing the first-pass effect from taking place, and more drug reaches the circulation.

Describe

Absorption of medications

Process involving movement of a substance from its site of administration, across body membranes, to circulating fluids.

lipid soluable and nonionized drugs are absorbed faster

Explain Bioavailability and routes of administration

Bioavailability: refers to the percentage of administered drug dose that reaches the circulation

route include IV, Oral, IM, PR, etc

Antagonists versus Agonists

• Drugs must bind to an appropriate receptor to achieve the desired effect
• Can bind onto several different types of sites, sometimes on proteins, lipids, etc.
• Drugs that produce a response are agonists - stimulates a receptor
• Drugs that block a response are antagonists – blocks a receptor, preventing something else from binding and acting

Controlled substances schedule – schedule I-V and what that means

• Schedule I
  • Drug has a high potential for abuse and no currently accepted medical use. No safety demonstrated.
• Schedule II
  • High potential for abuse. Has a currently accepted medical use but with a severe restriction. Abuse may lead to severe psychological and physical dependence.
• Schedule III
  • Potential for abuse, less than I and II, has currently accepted medical use. Abuse may lead to moderate or low physical dependence or high psychological dependence.
• Schedule IV
  • Low potential for abuse relative to classes I-III, has accepted medical use. Abuse may lead to limited physical or psychological dependence.
• Schedule V
  • Lowest potential for abuse with accepted medical use. Abuse may lead to limited physical or psychological dependence.

Elimination of medications – how monitored

• Removal of drug from the body.
• The rate at which drugs are excreted determines their concentration in the blood and tissues. This determines their duration of action.
• Main route of removal:Kidneys
• Other routes: liver, bile, feces, etc.
• Monitor kidney function by the following test: creatinine, BUN, Creatinine clearance
• Monitor liver function by the following tests: ALT, AST, GGT, bilirubin

Half-life

• Half-life (t ½) refers to the time it takes for one half of the drug concentration to be eliminated.
• Affected by metabolism and elimination.
• Liver or kidney dysfunction.

Peak and Trough

• Peak = rate of absorption of the drug
• Peak blood level is drawn at a specific time, according to the route of the drug given
• Trough = rate of elimination of the drug
• Trough blood level is drawn immediately before the next dose is given
• Ex. Aminoglycosides

Superinfection

Protein binding and the effect on available medication

• Protein-binding effect – can’t bind with receptors and so inactive
• Free drugs – active
• Important to check the protein-binding percentage of all drugs administered.
• Important to check the patient’s serum protein and albumin levels.

General guidelines for providing patient teaching

• General information
• How to self administer medication
• Diet considerations
• Side effects
• Cultural considerations
• Take medication as prescribed by your health care provider. If you have questions, call.
• Keep medication in original labeled container and store as instructed.
• Keep all medicines out of reach of children. Remind grandparents and visitors to monitor their purses and luggage when visiting.
• Before using any OTC drugs (including aspirin, laxatives, etc.), check with your health care provider. Pharmacists are good resources to ask before buying or using a product.
• Bring all medications with you when you visit the health care provider.
• Know why you are taking each medication and under what circumstances to notify the health care provider.
• Alcohol may alter the action and absorption of the medication. Use of alcoholic beverages is discouraged around the time you take your medications and is absolutely contraindicated with certain medications.
• Smoking tobacco alters absorption of some medications (e.g., theophylline-type drugs, tranquilizers, antidepressants, pain medications). Consult your health care provider or pharmacist for specific information.
• See Box 2-3

Therapeutic range- narrow range

• The range between having therapeutic effect and being toxic
• Some drugs are very narrow, some have wide margins.
• theraputic drug monitoring– especially important for drugs that have a narrow therapeutic range

Side effects versus Adverse effect

Side Effects:

 how is absorption of medications affected in Elderly patients?

• Slower absorption of oral medications
• Impaired circulation can delay transportation of drugs to the tissues
• Drugs metabolized more slowly & less completely
• Drugs excreted less completely
• See Table 11-1

Absorption

• Slow
• Increase alkaline GI secretions
• Decrease motility
• Distribution
• Loss of protein binding sites
• Loss of body water
• Increase in body fat

Pediatric patients and how to administer oral medications

• Oral route
  • Syringe:oral syringes ensure more exact dosing of med and are relativelly easy to use.
    
  • Placement: placed in mouth and pointed toward the buccal mucosa on either side of the mouth. allowing the med to fall too close to the front of the mouth increases the likelihood that medication will be spit out pointing the syringe directly toward the back of the mouth may increase the risk of gagging or choking.
    
  • To crush or not to crush?Nurses may need to crush pills or dissolve capsules in fluid for administration to pediatric clients.
    
  • Small volumes, not added to infant formula
  • IM should be given in vastus lateralis
    
• Other routes

Pediatric patients and age adaptations for medication administration and teaching

• Toddler:
• Preschoolers
• School-age children
• Older-age and adolescent

Penicillin

Class:Anti-infective/Antibacterials/Penicillins   “cillin”   bacterialcidal. Inhibits enzyme in cell wall synthesis. Most gm – and gm + cocci & bacilli.

type of drug:bacterialcidal/bacteriostatic

uses and action:PCN and cephalosporins work by messing up the cell wall building system!

side effects: Rash (but not a true allergy), Diarrhea, Stomach upset,Nasea, vomiting.

adverse reactions:Hypersensitivity, Gastrointestinal symptoms, Neurotoxicity, Renal dysfunction, superinfections,

patient teaching:

Half Life: Short

Penicillins:

Basic:penicillin G, penicillin V

Broad Spectrum:Amoxicillin, ampicillin, bacampicillin

Penicillinase-Resistant penicillin: cloxacillin, dicloxacillin, methicillin, nafcillin, oxacillin

Penicillinase

• The bacteria to produce penicillin-destroying enzymes
• Potassium clavulanate inhibits penicillinase: combined with penicillin

cephalosporin

Class:Anti-infective/Antibacterials/Penicillins   “cillin”   bacterialcidal. Inhibits enzyme in cell wall synthesis. Most gm – and gm + cocci & bacilli.

type of drug:bacterialcidal/bacteriostatic

uses and action:PCN and cephalosporins work by messing up the cell wall building system! Treat infections of:

• Skin, Bone, Heart, Blood, Respiratory tract, Gastrointestinal tract, Urinary tract

Cephalosporins   “cef”  “ceph”   Cef the “GIANT” (Gi; nausea, vomiting, diarrhea   Increase in glucose values   Anaphylaxis may occur; alcohol may cause vomiting    Nephrotoxicity   Thrombocytopenia)

side effects: Diarrhea, Stomach upset,Nasea, vomiting.

adverse reactions:Hypersensitivity, Gastrointestinal symptoms, Neurotoxicity, Renal dysfunction, anemia, superinfections, Thrombophlebitis (when given IV), Sterile abscess (when given IM)

patient teaching:condraindicated if renal disease, lactation, hypersensitivity to penicillins, cephalosporins

Half Life: Short

• First Gen: good gram-positive coverage
• Second:good gram-positive coverage; some gram-negative coverage
• Third:less gram-positive coverage; more gram-negative coverage
• Fourth: good gram-negative coverage

P435

First Gen:Cefadroxil, cefazolin sodium, cephalexin, cephalothin, cephapirin sodium, cephradine

Second Gen:cefaclor, cefamandole, cefmetazole sodium, cefonicid sodium, ceforanide, cefotetan, cefoxitin sodium, cefprozil monohydrate, cefuroxime

Third:cefdinir, cefixime, cefoperazone, cefotaxime, cefpodoxime, ceftazidime, ceftriaxome, ceftibuten, moxalactam disodium, cefditoren

fourth gen: cefepime

Macrolides

Macrolides   “mycin”  bacteriostatic. Inhibits synth of proteins in bact…for clients allergic to Pen, Gm-and Gm+ coverage….U/*L respiratory, GI, Urinary, skin, soft tissue

Class:antibacterial

uses and action:

• Proteins make up much of a bacterial cell’s structure.
• Macrolides block the bacterial cell’s machinery for making new proteins, leaving the cell unable to function.
• In low doses, Emycin stops bacteria from multiplying; in higher doses, it kills the bacteria
• Macrolides can kill bacteria that doesn’t have a cell wall (unlike PCNs and cephalosporins)
  • This is why emycin works on chlamydia and whooping cough (PCN doesn’t work at all on these!)
    • Bacteriostatic: inhibits protein synthesis in the bacterial cell
  • Primarily used for respiratory, gastrointestinal, urinary, skin, and soft tissue infections

side effects: 

• STOMACH UPSET!!!!
• Better with clarithromycin and azithromycin, but horrible with erythromycin!
• Always take with food or milk for this reason!

adverse reactions:

• Hypersensitivity
• Gastrointestinal effects
• Hepatotoxicity
• Jaundice

Patient teaching:p440 renal insufficiency is not a contraindication for macrolide use. Normally food does not hamper the absorption of acid resistant macrolides

Half Life: Short(except for dirithromycin which is 20-50hrs)

macrolides, lincosamides, and tetracyclines are primarily bacteriostatic while vancomycin, aminoblycosides, and fluoroquinolones are bactericidal

Drugs in this class

Macrolides: azithromycin, clarithromycin, dirithromycin, and erythromycin which is (frequently prescribed to patients who are hypersensitive to PCN)

Class:antibacterial

uses and action:

• Also blocks protein making machinery of certain bacteria
• We don’t give these drugs to children 8 and younger due to the effect on bone and tooth enamel.
• Used to treat chlamydia, but not gonorrhea (now resistant)
• The BEST for treating some life threatening infections such as cholera and anthrax!
• Action: inhibit protein synthesis in the bacterial cell; bacteriostatic
• Broad spectrum
  • Bacteria: gram – and gram +
• Effective against: protozoa, Mycoplasma, Rickettsia, Chlamydia, syphilis, Lyme disease

side effects:

• Nausea
• Vomiting
• Diarrhea
• photosensitivity

adverse reactions:

• Do not give to children.
• Affects tooth development from:
  • Fourth month of fetal development to 8 years old
  • Temporary and permanent discoloration of developing teeth
• Photosensitivity
• Superinfection
• Teratogenic in the first trimester of pregnancy
• Ototoxicity
• Renal toxicity

Patient teaching:

• Not to be taken with antacids, milk due to absorption issues.
• TCN increases digoxin absorption, which may result in dig toxicity
• Take on an empty stomach, meaning 1 hour before, or 2 hours after
  • Except for minocycline (Minocin) and doxycycline… absorption actually improves if taken with food for these 2 drugs

Half Life: Short but longer than PCN Cephalosporins and macrolides

macrolides, lincosamides, and tetracyclines are primarily bacteriostatic while vancomycin, aminoblycosides, and fluoroquinolones are bactericidal