Local Anesthetics | Categories and Calculations | INBDE, ADAT
TLDRIn this engaging video, Ryan dives into the world of pharmacology, specifically focusing on local anesthetics, which are crucial for dental procedures. He explains the two main categories of local anesthetics: amides and esters, highlighting their differences in metabolism and usage. Ryan emphasizes the importance of understanding the pharmacodynamics and pharmacokinetics of these drugs, which affects their efficacy and safety. He also provides valuable insights into calculating anesthetic concentrations and the role of epinephrine as a vasoconstrictor. The video is packed with high-yield facts for dental board exams and clinical practice, making it an invaluable resource for dental students and professionals alike.
Takeaways
- 🎓 **Pharmacology for Dental Boards**: Pharmacology is a challenging topic for the dental boards, but it has the least number of questions among all sections.
- 🔍 **Local Anesthetics Overview**: The video focuses on local anesthetics, covering amides vs. esters, their pharmacodynamics, and pharmacokinetics, as well as calculations involving these anesthetics.
- 🧪 **Amides vs. Esters**: Amides are metabolized in the liver, while esters are metabolized by pseudocholinesterase in the blood plasma. Amides are safer and less commonly cause allergic reactions.
- 💊 **Memorization Tip**: For exam purposes, memorize one category (amides or esters) of local anesthetics to infer the other, using the 'cane' suffix as a clue for anesthetics.
- 🚫 **Ester Allergies**: Esters are less commonly used due to higher toxicity and a higher rate of allergic reactions, often related to the presence of a methyl group.
- 👶 **Pediatric Considerations**: Lidocaine is the safest anesthetic for children, while bupivacaine (Marcaine) is not recommended for pediatric use.
- 🕒 **Duration of Action**: Bupivacaine has the longest duration, whereas articaine (Septacaine) has the shortest, with different concentrations available for various uses.
- 🧠 **Pharmacodynamics**: Local anesthetics work by blocking sodium channels in the neuron's membrane, requiring the drug to penetrate the neuron to be effective.
- 💊 **Pharmacokinetics**: Factors affecting the body's processing of local anesthetics include blood flow, lipid solubility, protein binding, and pKa levels.
- ⚖️ **Calculating Anesthetics**: A cartridge of anesthetic contains 1.8 mL of liquid, weighing 1.8 grams. The actual amount of anesthetic can be calculated based on the percentage concentration.
- 📚 **Key Numbers to Remember**: For a healthy patient, the maximum amount of epinephrine is 0.2 mg, and for a cardiac patient, it's 0.04 mg. Maximum lidocaine dosage varies with and without a vasoconstrictor.
Q & A
What is the main topic of Ryan's next series?
-The main topic of Ryan's next series is pharmacology, specifically focusing on local anesthetics, antibiotics, and analgesics.
How many questions are typically found in the pharmacology section of the part two dental boards?
-There are typically 31 questions in the pharmacology section of the part two dental boards.
What are the two main categories of local anesthetics discussed in the video?
-The two main categories of local anesthetics discussed are amides and esters.
Which enzyme is responsible for metabolizing ester local anesthetics?
-Ester local anesthetics are metabolized by the enzyme called pseudocholinesterase in the blood plasma.
Why are esters less commonly used than amides in dentistry?
-Esters are less commonly used because they are more toxic and have a higher rate of allergic reactions compared to amides.
What is the safest anesthetic to use in children according to the video?
-Lidocaine is the safest anesthetic to use in children.
Which local anesthetic has the longest duration of action?
-Bupivacaine, also known as marcaine, has the longest duration of action among the local anesthetics discussed.
What is the primary mechanism of action for local anesthetics?
-Local anesthetics primarily work by blocking sodium channels in the membrane of a neuron, preventing depolarization and the transmission of pain signals.
How does increased blood flow to the site of injection affect the duration of action of a local anesthetic?
-Increased blood flow to the site of injection results in a shorter duration of action for the local anesthetic, as the drug is carried away from the site more quickly.
What is the significance of the pKa value in relation to local anesthetics?
-The pKa value indicates the acid strength of the local anesthetic. A lower pKa means the drug is more acidic and tends to give up its proton faster, leading to a faster onset of action because more of the drug is in the non-ionized form, which can diffuse through the neuron membrane more quickly.
How does epinephrine function as a vasoconstrictor in local anesthetics?
-Epinephrine prolongs numbness by reducing blood flow to the area, decreases toxicity by limiting the amount of local anesthetic entering the bloodstream, and promotes hemostasis by constricting blood vessels and reducing bleeding.
What is the maximum recommended amount of epinephrine for a systemically healthy patient (ASA 1)?
-For a systemically healthy patient, the maximum recommended amount of epinephrine is 0.2 milligrams.
Outlines
📚 Introduction to Dental Pharmacology Series
Ryan introduces the dental pharmacology series, emphasizing its importance for the dental boards, and mentions the reduced number of questions in this section. He thanks his audience for their support and shares an upgrade to a professional microphone for better audio quality. The focus is on high-yield topics for the Dental Board Exam, with an aim to provide both exam preparation and clinical application knowledge. The series begins with local anesthetics, covering their categories, pharmacodynamics, pharmacokinetics, and calculations. Ryan provides a comprehensive list of local anesthetics for exam purposes, highlighting the importance of distinguishing between the two main categories: amides and esters, and their respective metabolism in the liver and blood plasma.
💊 Commercial Local Anesthetics and Their Characteristics
Ryan discusses individual commercially available local anesthetics, providing one or two high-yield facts for each. Lidocaine is highlighted as the safest anesthetic for children, while bupivacaine is contraindicated in children due to its safety profile. Articaine causes the least vasodilation, and articaine with an ester chain is metabolized in both the liver and blood plasma. Prilocaine is associated with methemoglobinemia. The duration of action for each anesthetic is covered, with bupivacaine being the longest-lasting and articaine the shortest. The concentrations at which these anesthetics are packaged are also discussed, with a focus on their clinical relevance.
🧠 Pharmacodynamics and Mechanism of Local Anesthetics
Pharmacodynamics is explored, focusing on the drug's effect on the body. Local anesthetics are described as sodium channel blockers, which prevent pain signal transduction by blocking sodium channels on the neuron's membrane. The importance of the drug's ability to penetrate the neuron membrane and block the channel from within is emphasized. The impact of an acidic environment on the efficacy of local anesthetics in inflamed tissue is discussed, as well as the concept of critical length for anesthesia. The role of blood flow, lipid solubility, and protein binding in the duration of action of local anesthetics is also covered.
🧮 Calculations for Local Anesthetics
Ryan presents a method for calculating local anesthetic concentrations, starting with the fact that one milliliter of liquid at sea level weighs one gram. He explains how to determine the weight of the local anesthetic within a cartridge, taking into account the percentage concentration. The process involves starting with an 18-milligram block for a 1% solution and adjusting based on the specific percentage of the anesthetic. An example calculation for 2% lidocaine is provided, as well as a practice question for calculating the amount of epinephrine in a solution. The importance of memorizing certain PK values for amide local anesthetics is also mentioned.
💡 Vasoconstrictors in Local Anesthetics and Key Numbers to Remember
The role of epinephrine as a vasoconstrictor in local anesthetics is explained, with its three main purposes: prolonging numbness, reducing toxicity, and promoting hemostasis. The video emphasizes that epinephrine counteracts the vasodilating properties of local anesthetics, resulting in a net vasoconstriction. Key numbers for the maximum amount of epinephrine for a systemically healthy patient (0.2 mg) and for a cardiac patient (0.04 mg) are provided. The maximum amount of lidocaine without and with a vasoconstrictor is also discussed, highlighting the reduced toxicity when a vasoconstrictor is used due to decreased blood flow to the area.
📝 Conclusion and Final Reminders
Ryan concludes the video by encouraging the audience to re-watch and pause as needed, hoping they found the information helpful. He asks for likes and subscriptions to the channel for more content on local anesthetics, pharmacology, and dentistry. The video ends with a reminder of the importance of the covered topics and a prompt for viewers to join him in the next video of the series.
Mindmap
Keywords
💡Pharmacology
💡Local Anesthetics
💡Amides vs. Esters
💡Pharmacodynamics
💡Pharmacokinetics
💡Vasoconstrictors
💡Lidocaine
💡Bupivacaine
💡Mepivacaine
💡Prilocaine
💡Epinephrine Concentration
Highlights
Pharmacology is a challenging topic for the dental boards, with only 31 questions making it less daunting.
Ryan has upgraded to a professional microphone to improve audio quality for the series.
The focus is on high-yield topics essential for the Dental Board Exam and clinical application.
Local anesthetics are categorized into amides and esters, with amides being safer and less toxic.
Lidocaine is the safest anesthetic for children, while bupivacaine is not recommended for them.
Mepivacaine causes the least amount of vasodilation, often packaged with epinephrine.
Articaine has a unique ester chain and is metabolized in both the liver and blood plasma.
Prilocaine is linked to methemoglobinemia, a blood disorder, especially when used in higher concentrations.
Bupivacaine has the longest duration of all local anesthetics, while articaine has the shortest.
Local anesthetics are less effective in inflamed or infected tissue due to the acidic environment affecting drug ionization.
Pharmacokinetics involves how the body processes the drug, including blood flow, lipid solubility, and protein binding.
Epinephrine as a vasoconstrictor in local anesthetics prolongs numbness, reduces toxicity, and promotes hemostasis.
A simple calculation method is introduced for determining the amount of local anesthetic in a cartridge.
The video provides a practice question on calculating the amount of epinephrine in a local anesthetic solution.
Key numbers to remember include the maximum amount of epinephrine for a healthy patient and a cardiac patient.
Lidocaine without a vasoconstrictor has a maximum dosage of 4.4 mg per kilogram, and with a vasoconstrictor, it's 7 mg per kilogram.
The video concludes with encouragement to re-watch and pause as needed for better understanding.
Transcripts
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