Lecture 5 Flashcards
Oral Sedation Advantages
Well accepted Easy Cost Effective Low Adverse Reaction No needles
Oral Sedation Disadvantages
Compliance Latent Period Erratic Difficult to titrate Difficult to alter Prolonged duration- may need escort home 1st Pass Metabolism
Enteral Absorption
Oral, Sublingual, Rectal
Parenteral
IV, IM, IN, inhalation, Transdermal, Transmucosal
Bioavailability
The fraction of drug that reaches the central circulation
Proteins that drugs bind to
Most common: Albumin
2nd most common: a-acid glycoprotein
Where is the drug metabolized?
Most often in LIVER
CYP 450
Cleaves prodrug into active drug or further metabolizes drug
Common Ways of Metabolizing Drugs
CYP 450 and Glucoronidation
Acidic drugs better absorbed in _______ environment, like the _________
acidic; stomach
Basic better metabolize in more basic places like small intestine
Rationale for oral sedation
Good nights sleep, decrease pre-op anxiety, decrease intraoperative anxiety/pain
NOT for making uncooperative patients cooperative
Oral agents rules in Ohio
All agents must be administered concomitantly- and can only prescribe ONE dose
Sublingual Advantages
Enters systemic circulation
Cost
Low adverse rxn
No 1st pass effect
Sublingual Disadvantages
Cooperation needed
Difficult to titrate
Difficult to alter
Sublingual
Considered Enteral
Sublingual Characteristics
Deeper level of sedation
Higher peak plasma levels
Decreased time to sedation
Examples of Sublingual Meds
Nitroglycerin, Nifedipine, Fentanyl lollipop
Intranasal
Rapid onset, goes directly into systemic circulation
IM advantages
Quick onset
Max effect at 30 min
Reliable and predictable
Cooperation not essential
IM Disadvantages
Not titratable Not very reversible Prolonged Injection--> painful Injury--> nerve damage Have to use needle!
Sites for IM
Gluteal, Ventrogluteal, Vastus Lateralis, Deltoid
Gluteal IM
Least well perfused
Can cause damage to Sciatic N
Don’t do in little kids!
Do in Gluteus Medius, NOT gluteus maximus
Deltoid IM
Best perfused, best absorption, holds 4mL
Don’t do in little kids
Vastus Lateralis IM
Do for kids!!
Holds 15 mL, quicker uptake than Deltoid
IM Complications
Nerve damage Periostitis Hematoma Abscess Sloughing of tissue
Clark’s Rule of Dosing
Weight/150 * Adult dose
Young’s Rule of Dosing
Age/Age+12 * Adult dose
Most accurate dosing for children
Age related body surface area as a percent of average adult body surface area
Rectal Advantages
Relatively rapid
Less SE’s and lower intensity SE’s
Cost and Ease - higher acceptance
Less hepatic 1st pass effect (only 1/3)
Rectal Disadvantages
Inconvenient Intestinal irritation Difficult to titrate Difficult to alter Prolonged Duration Erratic- variable absorption
Superior vs Middle vs Inferior Rectal veins
Superior enters portal system/Liver via inf mesenteric
Middle and Inferior empty into circulation w/ internal iliac V
Drugs to use with Rectal
Midazolam or Diazepam
IV advantages
Rapid onset Highly effective Shorter recovery ABILITY TO REDOSE Ability to reverse Titratable
IV disadvantages
Venipuncture Inc monitoring Pain from needle Potential catheter injury Most cannot be reversed Pt cooperation
Drugs that reverse benzodiazepines
Miloxam and Flumazenil
Benzodiazepines: Site of Action
GABA and how Cl is transferred into cell
Benzodiazepines Physio effects
Reduction of hostile and aggressive behavior, reduces fear, relaxes skeletal muscles, anticonvulsant, sedation, and hypnosis
Contraindications to Benzodiazepines
Allergy to them
Acute Narrow angle glaucoma
Benzodiazepines: Uses
Sedative
Anxiolysis
Anticonvulsant
Amnesia
Benzodiazepines effects on Respiration
Little when used alone and orally
Mild when used alone and slowly titrated IV
Unconsciousness and loss of airway in high or bolus dose
Benzodiazepines effects on CV
Minimal
Benzodiazepines Adverse Effects
Disinhibition
Ataxia
Prolonged drowsiness or amnesia
Benzodiazepines drug interactions
Opioids- additive resp depression
Other CNS sedatives - barbiturates, antidepressants, clonidine- synnergistic
Cimetidine- Inc T1/2 of Diazepam
Half life of Midazolam
1-4 hrs
Half life of Diazepam
Pt’s age
Oral Benzo drugs
Diazepam, Midazolam, Flumazenil, Lorazepam
Flow of Benzodiazepines throughout body
Go first (75%) to vessel rich tissues like brain, then (19%) to muscles, then (6%) to far, and finally (1%) to vessel-poor group
Diazepam Characteristics
Dissolved in organic solvent- propylene glycol
Sodium Benzoate
Burns on injection
5-15 mg for 1 hr appointment
Midazolam
Rapid absorption orally
50% lost to 1st pass effect
Slow effect-site equilibration time
Short duration of action
Midazolam risk
Greater risk of early respiratory depression
Titrate how much Diazepam or Midazolam
2.5mg Diazepam or 1 mg Midazolam
Diazepam Oral Dosing
2-10 mg tabs for adults
1-2 mg for children > 6mo
Midazolam Oral Dosing
250-500 mcg/kg (
Lorazepam
For pts w/ impaired liver fxn because does not require hepatic oxidation
0.05 mg/kg IM/IV so
Triazolam
Transient anterograde amnesia Cat X May cause higher freq of psychiatric SE's 0.125-0.25 mg orally Long half life
Zaleplon
10 mg orally
NOT a benzodiazepine
Metabolized by Aldehyde Oxidase
Zolpidem
10 mg orally
NOT a benzodiazepine
Short T1/2, potentiates GABA
Temazapam
For sleeping
7.5-15mg orally
