NEET MDS Lessons
Pharmacology
Local Anesthetics
1. Procaine (Novocaine)
a) Classic Ester type agent, first synthetic injectable local anesthetic.
b) Slow onset and short duration of action
2. Tetracaine (Pontocaine)
a) Ester type agent--ten times as potent and toxic as procaine.
b) Slow onset but long duration of action.
c) Available in injectable and topical applications.
3. Propoxycaine (Ravocaine)
a) Ester type agent–five times as potent and toxic as procaine.
b) Often combined with procaine to increase duration of action.
4. Lidocaine (Xylocaine)
a) Versatile widely used amide type agent.
b) Two - three times as potent and toxic as procaine.
c) Rapid onset and relatively long duration of action.
d) Good agent for topical application.
5. Mepivacaine (Carbocaine)
a) Amide type agent similar to lidocaine.
b) Without vasoconstrictor has only short duration of action.
6. Prilocaine (Citanest)
a) Amide type agent — less potent than lidocaine.
b) Without vasoconstrictor has only short duration of action.
c) Metabolized to o-toluidine which can cause methemoglobinemia — significant only with large doses of prilocaine.
d) Higher incidences of paresthesia reported with 4 % preparation
7. Bupivacaine (Marcaine)
a) Amide type agent of high potency and toxicity.
b) Rapid onset and very long duration of action even without vasoconstrictor.
8. Articaine (Septocaine)
a) Amide type agent
b) Only amide-type local anesthetic that contains an ester group, therefore metabolized both in the liver and plasma.
c) Approved by the FDA in 2000
d) Evidence points to improved diffusion through hard and soft tissues as compared to other local anesthetics.
e) Reports of a higher incidence of paresthesia, presumably due to the 4% concentration
f) Not recommended for use in children under 4 years of age
DOBUTAMINE
It is a derivative of dopamine and has relatively β1 -selective action and it also activates α1 receptors and do not have D1 receptor agonistic property. It increases the force of myocardial contraction and cardiac output without significant change in heart rate, blood pressure and peripheral resistance. It is used as inotropic agent and for short term management of CHF and also in patients who are unresponsive to digitalis.
Mefenamic acid
Analgesic, anti‐inflammatory properties less effective than aspirin
Short half‐lives, should not be used for longer than one week and never in pregnancy and in children.
Enhances oral anticoagulants
Used to treat pain, including menstrual pain. It decreases inflammation (swelling) and uterine contractions.
Benzodiazepines
All metabolites are active sedatives except the final glucuronide product.
Elimination half-life varies a great deal from drug to drug.
?-Hydroxylation is a rapid route of metabolism that is unique to triazolam,
midazolam, and alprazolam.
This accounts for the very rapid metabolism and short sedative actions of these
drugs.
Pharmacological effects of benzodiazepines
- Antianxiety.
- Sedation.
- Anticonvulsant (including drug-induced convulsions).
- Amnesia, especially drugs like triazolam.
- Relax skeletal muscle (act on CNS polysynaptic pathways).
Indications
- IV sedation, (e.g., midazolam, diazepam, lorazepam).
- Antianxiety.
- Sleep induction.
- Anticonvulsant (e.g., diazepam, clonazepam).
- Panic disorders.
- Muscle relaxation.
Adverse effects
- Ataxia, confusion.
- Excessive sedation.
- Amnesia (not a desired effect with daytime sedation).
- Altered sleep patterns (increase stage 2 and decrease stage 4 sleep).
Clotrimazole: Clotrimazole is a potent, specific inhibitor of p450 enzymes.
It is used in some antifungal medications, and in the treatment of yeast infections.
FUNDAMENTALS OF INJECTION TECHNIQUE
There are 6 basic techniques for achieving local anesthesia of the structures of the oral cavity:
1. Nerve block
2. Field block
3. Infiltration/Supraperiosteal
4. Topical
5. Periodontal ligament (PDL)
6. Intraosseous
Nerve block- Nerve block anesthesia requires local anesthetic to be deposited in close proximity to a nerve trunk. This results in the blockade of nerve impulses distal to this point. It is also important to note that arteries and veins accompany these nerves and can be damaged. To be effective, the local anesthetic needs to pass only through the nerve membrane to block nerve conduction Field block/Infiltration/Supraperiosteal - Field block, infiltration and supraperiosteal injection techniques, rely on the ability of local anesthetics to diffuse through numerous structures to reach the nerve or nerves to be anesthetized:
- Periosteum
- Cortical bone
- Cancellous bone
- Nerve membrane
Topical - Topical anesthetic to be effective requires diffusion through mucous membranes and nerve membrane of the nerve endings near the tissue surface
PDL/Intraosseous - The PDL and intraosseous injection techniques require diffusion of local anesthetic solution through the cancellous bone (spongy) to reach the dental plexus of nerves innervating the tooth or teeth in the immediate area of the injection. The local anesthetic then diffuses through the nerve membrane
Ampicillin offered a broader spectrum of activity than either of the original penicillins and allowed doctors to treat a broader range of both Gram-positive and Gram-negative infections. Ampicillin is often used in molecular biology as a test for the uptake of genes (e.g., by plasmids) by bacteria (e.g., E. coli)