Valley Pharmacology Flashcards
Name drugs used in anesthesia that have a small volume of distribution.
Muscle Relaxants - these drugs are water soluble, therefore they do not cross the lipid cell membrane, or into the fat - stay in the extracellular compartment (plasma + interstitial volume)
Name drugs used in anesthesia that have large volumes of distribution.
Induction agents - these drugs are lipid soluble, therefore they cross into the intracellular and fat compartments. There is a small amount in the watery areas (plasma and interstitial fluid) and higher concentration in fatty areas.
What combination will most facilitate trapping of a local anesthetic by the fetus?
maternal alkalosis and fetal acidosis
What condition most prevents passage of local anesthetic from fetus to mom?
fetal acidosis
What type of ions to weak acids unite with?
positively charged ions such as Na+, Mg++, or Ca++
i.e. sodium pentobarbital
What type of ions do weak bases unite with?
negatively charged ions such as Cl- or SO4–
i.e. morphine sulfate
What single change in a property of a local anesthetic will result in a more potent AND longer acting agent?
An increase in lipid solubility will increase the duration of action and the potency.
What factor is more important to duration of action of a local anesthetic: protein-binding or lipid-solubility
protein-binding is more important for the duration of action, even though increased lipid-solubility can also increase the DOA
List in order the tissue with highest blood flow (in relation to local anesthetic toxicity/reduced DOA) and Sally
- intravenous
- tracheal
- intercostal
- caudal
- paracervical
- epidural
- brachial plexus
- subarachnoid, sciatic, femoral
- subcutaneous
In Time I Can Please Everyone But Susie
or
I Think I Can Push Each Bolus Slowly For Safety
List the plasma concentration and toxic manifestations of lidocaine.
1-5 mcg/mL –> analgesia, theraputic
5-10 mcg/mL –> light-headed, tinnitus, visual disturbances, numbness of tongue, muscle twitching
10-15 mcg/mL –> seizures, convulsions
15-25 mcg/mL –> unconsciousness, coma, respiratory arrest
> 25 mcg/mL –> cardiovascular depression
The action of which drug is not prolonged by the patient taking cimetidine?
- theophylline
- propranolol
- phenytoin
- atracurium
atracurium
Neonates need more succinylcholine per kg body weight than the young adult because the neonate has…
a larger volume of distribution and an immature neuromuscular junction
Alfentanil is eliminated faster than sufentanil because alfentanil has….
a smaller volume of distribution than sufentanil
What drugs are eliminated by zero order kinetics?
phenytoin
aspirin
alcohol
A drug will be eliminated slowly if…
its clearance is small and its volume of distribution is large.
600 mg of a drug is administered, and 60 hours later 75 mg remains. If this drug is eliminated by first order of kinetics, how much drug is eliminated in the next 40 hours?
56.25 mg
How many half-lives does it take to eliminate 98% of a drug?
6 half-lives
A weak acid becomes more than 50% non-ionized following intravenous injection (blood pH = 7.4). The pKa of this weak acid would be
greater than 7.4
i.e. 7.6 or 9.1 or 11.0
When injected into the body, any of the local anesthetics used currently in clinical practice will be more/less/completely ionized?
less than 50% nonionized
** the end of chapter quiz said that it should be more than 50% non-ionized, which is a typo. LA weak base + physiologic pH (more acidic than any current pKa) is base + acid = less non-ionized
Sodium drug has pKa of 8.2. When injected into the blood, this drug will become…?
more than 50% nonionized
Potency of a local anesthetic is determined by
lipid solubility
Duration of action of local anesthetics is determined by:
protein binding and lipid solubility
but more strongly by protein binding
Local anesthetics work on which segment(s) of the neuron?
axon only
Conduction block occurs when the ionized/nonionized local anesthetic binds to the voltage gated sodium channel on the outside/inside of the cell.
Conduction block occurs when the non-ionized local anesthetic binds to the VG sodium channel on the inside of the cell
You can make your own local anesthetic. If you want the local anesthetic to have a fast onset, you will want to have the local anesthetic have what pKa?
- 3
- 0
- 4
- 5
2.3
Injection of local anesthetic at which of the following sites is most likely to result in systemic toxicity?
- epidural space
- paracervical tissue
- intercostal muscles
- brachial plexus
intercostal muscles
What factor is more important to duration of action of a local anesthetic: protein-binding or lipid-solubility
but more strongly by protein binding
