Valley Pharmacology

Question 1

Name drugs used in anesthesia that have a small volume of distribution.

Answer 1

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)

Question 2

Name drugs used in anesthesia that have large volumes of distribution.

Answer 2

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.

Question 3

What combination will most facilitate trapping of a local anesthetic by the fetus?

Answer 3

maternal alkalosis and fetal acidosis

Question 4

What condition most prevents passage of local anesthetic from fetus to mom?

Answer 4

fetal acidosis

Question 5

What type of ions to weak acids unite with?

Answer 5

positively charged ions such as Na+, Mg++, or Ca++

i.e. sodium pentobarbital

Question 6

What type of ions do weak bases unite with?

Answer 6

negatively charged ions such as Cl- or SO4–

i.e. morphine sulfate

Question 7

What single change in a property of a local anesthetic will result in a more potent AND longer acting agent?

Answer 7

An increase in lipid solubility will increase the duration of action and the potency.

Question 8

What factor is more important to duration of action of a local anesthetic: protein-binding or lipid-solubility

Answer 8

protein-binding is more important for the duration of action, even though increased lipid-solubility can also increase the DOA

Question 9

List in order the tissue with highest blood flow (in relation to local anesthetic toxicity/reduced DOA) and Sally

Answer 9

1. intravenous
2. tracheal
3. intercostal
4. caudal
5. paracervical
6. epidural
7. brachial plexus
8. subarachnoid, sciatic, femoral
9. subcutaneous

In Time I Can Please Everyone But Susie
or

I Think I Can Push Each Bolus Slowly For Safety

Question 10

List the plasma concentration and toxic manifestations of lidocaine.

Answer 10

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

Question 11

The action of which drug is not prolonged by the patient taking cimetidine?

• theophylline
• propranolol
• phenytoin
• atracurium

Answer 11

atracurium

Question 12

Neonates need more succinylcholine per kg body weight than the young adult because the neonate has…

Answer 12

a larger volume of distribution and an immature neuromuscular junction

Question 13

Alfentanil is eliminated faster than sufentanil because alfentanil has….

Answer 13

a smaller volume of distribution than sufentanil

Question 14

What drugs are eliminated by zero order kinetics?

Answer 14

phenytoin
aspirin
alcohol

Question 15

A drug will be eliminated slowly if…

Answer 15

its clearance is small and its volume of distribution is large.

Question 16

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?

Answer 16

56.25 mg

Question 17

How many half-lives does it take to eliminate 98% of a drug?

Answer 17

6 half-lives

Question 18

A weak acid becomes more than 50% non-ionized following intravenous injection (blood pH = 7.4). The pKa of this weak acid would be

Answer 18

greater than 7.4

i.e. 7.6 or 9.1 or 11.0

Question 19

When injected into the body, any of the local anesthetics used currently in clinical practice will be more/less/completely ionized?

Answer 19

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

Question 20

Sodium drug has pKa of 8.2. When injected into the blood, this drug will become…?

Answer 20

more than 50% nonionized

Question 21

Potency of a local anesthetic is determined by

Answer 21

lipid solubility

Question 22

Duration of action of local anesthetics is determined by:

Answer 22

protein binding and lipid solubility

but more strongly by protein binding

Question 23

Local anesthetics work on which segment(s) of the neuron?

Answer 23

axon only

Question 24

Conduction block occurs when the ionized/nonionized local anesthetic binds to the voltage gated sodium channel on the outside/inside of the cell.

Answer 24

Conduction block occurs when the non-ionized local anesthetic binds to the VG sodium channel on the inside of the cell

Question 25

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?

2. 3
3. 0
4. 4
5. 5

Answer 25

2.3

Question 26

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

Answer 26

intercostal muscles

Question 27

What factor is more important to duration of action of a local anesthetic: protein-binding or lipid-solubility

Answer 27

but more strongly by protein binding