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
Loperamide
- Similar chemically and pharmacologically to Diphenoxylate.
- Slows gastrointestinal motility by effects on the circular and longitudinal muscles of the intestine.
- Not well absorbed following oral administration.
- Useful in the treatment of diarrhea.
α-glucosidase inhibitors
acarbose
miglitol
Mechanism
inhibit α-glucosidases in intestinal brush border
delayed sugar hydrolysis
delayed glucose absorption
↓ postprandial hyperglycemia
↓ insulin demand
Clinical use
type II DM
as monotherapy or in combination with other agents
Local anesthetic selection
Local anesthetics are typically divided into 3 main categories:
short, intermediate and long acting local anesthetics.
Based on duration of the procedure and the duration of the individual agents
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Infiltration |
Nerve block |
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Pulpal |
Soft tissue |
Pulpal |
Soft tissue |
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Short |
30 min |
2-3 hrs |
45 min |
2-3 hrs |
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Intermediate |
60 min |
2-3 hrs |
75-90 min |
3-4 hrs |
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Long |
40 min |
5-6 hrs |
3-4 hrs |
6-8 hrs |
Short acting agents
1. Mepivacaine 3 %
2. Lidocaine 2%
Intermediate acting agents
1. Lidocaine 2% 1:100000 epi
2. Lidocaine 2% 1:50000 epi
3. Mepivacaine 2% 1:20000 neocobefrin
4. Prilocaine 4%
5. Articaine 4% 1:100000 epi
Long acting agents
1. Bupivacaine 0.5% 1:200000 epi
Seizure classification:
based on degree of CNS involvement, involves simple ( Jacksonian; sensory or motor cortex) or complex symptoms (involves temporal lobe)
1. Generalized (whole brain involved):
a. Tonic-clonic:
Grand Mal; ~30% incidence; unconsiousness, tonic contractions (sustained contraction of muscle groups) followed by clonic contractions (alternating contraction/relaxation); happens for ~ 2-3 minutes and people don’t breathe during this time
Drugs: phenytoin, carbamazepine, Phenobarbital, lamotrigine, valproic acid
Status epilepticus: continuous seizures; use diazepam (short duration) or diazepam + phenytoin
b. Absence:
Petit Mal; common in children; frequent, brief lapses of consciousness with or without clonic motor activity; see spike and wave EEg at 3 Hz (probably relates to thalamocorticoreverburating circuit)
Drugs: ethosuximide, lamotrigine, valproic acid
c. Myoclonic: uncommon; isolated clinic jerks associated with bursts of EEG spikes;
Drugs: lamotrigine, valproic acid
d. Atonic/akinetic: drop seizures; uncommon; sudden, brief loss of postural muscle tone
Drugs: valproic acid and lamotrigine
2. Partial: focal
a. Simple: Jacksonian; remain conscious; involves motor or sensory seizures (hot, cold, tingling common)
Drugs: carbamazepine, phenytoin, Phenobarbital, lamotrigine, valproic acid, gabapentin
b. Complex: temporal lobe or psychomotor; produced by abnormal electrical activity in temporal lobe (involves emotional functions)
Symptoms: abnormal psychic, cognitive, and behavioral function; seizures consist of confused/altered behavior with impaired consciousness (may be confused with psychoses like schizophrenia or dementia)
Drugs: carbamazepine, phenytoin, laotrigine, valproic acid, gabapentin
Generalizations: most seizures can’t be cured but can be controlled by regular administration of anticonvulsants (many types require treatment for years to decades); drug treatment can effectively control seizures in ~ 80% of patients
Fourth Generation:
These are extended spectrum antibiotics. They are resistant to beta lactamases.
Cefipime
Cough is a protective reflex which helps in expulsion of respiratory secretion or foreign particles which are irritant to respiratory
tract. Irritation to any part of respiratory tract starting from pharynx to lungs carried impulses by afferent fibres in vagus and
sympathetic nerve to the cough centre in the medulla oblongata. \
Cough may be dry (without sputum or unproductive) or productive (with sputum production).
Classification for drugs used in cough.
I. Pharyngeal demulcents
Certain lozenges, linctus and cough drops containing glycerine, liquorice and syrups.
II. Expectorants
Sodium and potassium citrate
Sodium and potassium acetate
Potassium iodide
Ammonium chloride & carbonate
Acetylcysteine
Bromhexine
Guaiphenesin
III. Antitussive
i. Opioids
Codeine (as linctus) Pholcodeine
ii. Non-opioids
Noscapine
Dextromethorphan
Pipazethate
iii. Antihistaminics
Chlorpheniramine
Diphenhydramine
Promethazine
Erdosteine is recently introduced mucolytic with unique protective functions for the respiratory tract. It is indicated in the treatment of acute and chronic airway diseases such as bronchitis, rhinitis, sinusitis, laryngopharyngitis and exacerbations of chronic bronchitis.