Term
Describe the top view appearance of the open sodium channels. |
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Definition
positive charches are along the outside with the core negative charge so that sodium ions may pass. |
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Term
| Describe the top view appearance of the closed sodium channels. |
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Definition
| Positive channels are inward toward the core where the sodium channels are repelled and no longer can pass. |
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Term
| How do local anesthetics block nerve conductance? |
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Definition
By targeting sodium channels of nociceptive and other fibers. They bind to specific sites within the pore and block ion movement and AP propagation They decrease the sodium permeability during depolarization |
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Term
Fill in the blanks. The pKa of local anesthetics is optimal between _________ and _________. |
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Definition
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Term
True or False? and why? The unionized (deprotinated) form of procaine is the active form. |
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Definition
False The ionized, protinated form of procaine is active. |
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Term
| Describe the importance of balance between the protinated and deprotinated forms of procaine in anesthesia. |
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Definition
| The balance is delicate such that there is enough deprotinated forms of the drug to pass through the membrane of nerve cells while still maintaining its capability to convert to the active protinated form. |
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Term
| Where and in what form does procaine work? |
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Definition
| Procaine works on the cytoplasmic side as the protinated, ionized molecule; it needs the deprotinated, unionized form to pass through membranes. |
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Term
| How can procaine be toxic? |
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Definition
When procaine is metabolized, one of its end products is PABA(p-amino-benzoic acid). PABA is toxic to the CNS, may act as an allergen, and may interfere with sulfonamide antibiotics. |
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Term
| How can prilocaine be toxic? |
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Definition
Prilocaine can be metabolized via amidases which yields benzene rings with amides. These amides can be oxidized to o-toluidine, which can lead to anemia, heart disease, and cardioinsufficiency. o-toluidine can bind to hemoglobulins and decrease oxygen supply (anemia). |
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Term
When giving a local, order the following sensations from most effected to least effected: Cold, Warm, Pain, Touch, Pressure |
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Definition
| Pain>cold>warm>touch>pressure |
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Term
| Describe the SAR of local anesthetics |
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Definition
-pKa 7.5-9 -2 carbon linkage between amine and aromatic (cationic and hydrophobic group) -hydrophobicity electron donating groups increase activity electron withdrawing groups decrease activity R groups on aromatic ring increase hydrophobicity
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Term
| Spinal fluid contains little _________ activity. Anesthetics must defuse into the _________ for clearance. |
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Definition
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Term
| What can slow down the metabolism of local amide metabolism? |
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Definition
| increased steric bulk around amide. |
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Term
| List the neurotoxicities from local anesthetics. |
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Definition
Depression of cortical inhibitory pathways Convulsions from excess in blood Peripheral nerve toxicity in high doses |
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Term
| List the possible cardiovascular toxicities in local anesthetics. |
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Definition
Direct action on smooth muscle indirect action on autonomic nerves |
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Term
| When would you favor using an ester local anesthetic over an amide local anesthetic? |
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Definition
| If the patient has liver damage. |
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Term
| Amide-linked locals are degraded primarily by __________. Two steps occur in this metabolism, ___________ of the aromatic ring and ____________, which is followed by hydrolysis. |
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Definition
| liver microsomes, oxidation, N-dealkylation |
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Term
| Why are people more likely to have an allergic reaction to benzocaine and not lidocaine? |
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Definition
Benzocaine is an ester-linked local anesthetic. It by product is para-amino-benzoic acid (PABA), which may act as an allergen. The same goes for procaine. Lidocaine on the other hand is an amide-linked local anesthetic. |
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Term
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Definition
Benzocaine ester-linked local note: has no cationic group |
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Term
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Definition
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Term
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Definition
Bupivaine amide local long duration, high potency (16x procaine) |
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Term
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Definition
Ecgonine not an active anesthetic metabolite of cocaine |
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Term
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Definition
lidocaine amide-linked local 4x potency of procaine, medium duration |
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Term
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Definition
tetracaine Ester local Long acting 16x potency of procaine |
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Term
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Definition
Tropine inactive anesthetic No benzoyl group Analogue anesthetic |
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