NEET MDS Lessons
Pharmacology
Griseofulvin
- Griseofulvin is an antifungal drug. It is used both in animals and in humans, to treat ringworm infections of the skin and nails. It is derived from the mold Penicillium griseofulvum.
- It is administered orally.
Immunosuppressive antibodies can be classified mainly into monoclonal and polyclonal antibodies, targeting specific components of the immune system.
-
Monoclonal Antibodies:
-
Basiliximab: Targets the IL-2 receptor on T cells, inhibiting T-cell activation. It is FDA approved for use in renal transplantation to prevent acute rejection.
-
Alemtuzumab: Targets CD52, a protein found on the surface of mature lymphocytes. It is used for treating chronic lymphocytic leukemia and as an induction agent in kidney transplantation.
-
Rituximab: Targets CD20 on B cells, leading to B-cell depletion. It is used in various conditions, including non-Hodgkin lymphoma and rheumatoid arthritis.
-
Daclizumab: Targets the IL-2 receptor (CD25) and is used in renal transplantation to prevent acute rejection.
-
Eculizumab: Targets complement component C5, inhibiting the complement cascade. It is used in conditions like paroxysmal nocturnal hemoglobinuria and atypical hemolytic uremic syndrome.
-
-
Polyclonal Antibodies:
-
Rabbit Antithymocyte Globulin (rATG): A polyclonal antibody that targets multiple T-cell surface markers, leading to T-cell depletion. It is used as an induction agent in kidney transplantation and for treating acute rejection.
-
Equine Antithymocyte Globulin (eATG): Similar to rATG, it targets T cells and is used in transplantation settings.
-
-
Mechanisms of Action:
-
Depletion of Immune Cells: Many antibodies work by depleting specific immune cell populations (e.g., T cells or B cells) to reduce the immune response against transplanted organs or in autoimmune diseases.
-
Blocking Activation Signals: Some antibodies block key receptors involved in T-cell activation, preventing the immune response from being initiated.
-
Inhibition of Complement Activation: Antibodies like eculizumab inhibit the complement system, which can contribute to tissue damage in antibody-mediated rejection.
-
-
Clinical Applications:
-
Organ Transplantation: Antibodies are commonly used to prevent rejection in kidney, liver, and heart transplants.
-
Autoimmune Diseases: They are also used in treating conditions like rheumatoid arthritis, lupus, and multiple sclerosis.
-
-
Potential Side Effects:
- Infections: Due to immune suppression, patients are at increased risk of infections.
- Allergic Reactions: Some patients may experience allergic reactions to antibody therapies.
- Infusion Reactions: These can occur during the administration of monoclonal antibodies, leading to symptoms like fever, chills, and hypotension.
ANTIDEPRESSANTS
Monoamine uptake inhibitors
1. Tricyclic antidepressants (TCAs)
2. Selective serotonin reuptake inhibitors (SSRIs)
3. Serotonin-norepinephrine reuptake inhibitors(SNRIs)
4. Norepinephrine reuptake inhibitor
Monoamine oxidase inhibitors (MAOIs)
Monoamine receptor antagonists
Needle selection
Nerve blocks:
Inferior alveolar- 25 G short (LLU technique)
PSA- 25 G short
Mental/Incisive- 25 G short
Palatal- 27/30 G short/ultrashort
Gow-Gates/Akinosi- 25 G long
Infraorbital- 25 G long
Field Block:
ASA 25/27 short
Infiltration:
Infiltration/SP 25/27 short
PDL/Intraosseous
PDL 27/30 short
Intraosseous 30 short/ultrashort
Topical Anesthetics
Benzocaine
Benzocaine is a derivative of procaine, an ester type local anesthetic, and is poorly soluble in water and is
available only as a topical anesthetic.
- Localized allergic reactions are sometimes encountered
- Overdosing is unlikely as benzocaine is poorly absorbed into the blood, which decreases the likelihood of systemic toxicity.
- The onset of surface anesthesia is rapid requiring less than one minute.
Tetracaine
- Tetracaine is an ester type local anesthetic
- Topically applied tetracaine as opposed to benzocaine has a prolonged duration of action.
Cocaine
- Cocaine is a ester type anesthetic that is used exclusively as a topical agent.
- Cocaine is unique among topical and injectable anesthetics in that it has vasoconstrictive as well as anesthetic properties. It is used sparingly because of its abuse potential but is still used when hemostasis of mucous membranes is essential.
- Cocaine is generally available in concentrations of 2-10 % solution.
Lidocaine
- Lidocaine is an amide local anesthetic that is available in injectable and topical formulations.
- It is available in gel, viscous solution, ointment and aerosol preparations in concentrations ranging from 2-10 %.
- The onset of anesthesia is slower relative to benzocaine but, the duration is about the same.
- Absorption into the bloodstream is greater than benzocaine providing a greater risk of systemic toxicity.
Antiarrhythmic Drugs
Cardiac Arrhythmias
Can originate in any part of the conduction system or from atrial or ventricular muscle.
Result from
– Disturbances in electrical impulse formation (automaticity)
– Conduction (conductivity)
– Both
MECHANISMS OF ARRHYTHMIA
ARRHYTHMIA – absence of rhythm
DYSRRHYTHMIA – abnormal rhythm
ARRHYTHMIAS result from:
1. Disturbance in Impulse Formation
2. Disturbance in Impulse Conduction
- Block results from severely depressed conduction
- Re-entry or circus movement / daughter impulse
Types of Arrhythmias
• Sinus arrhythmias
– Usually significant only
– if they are severe or prolonged
• Atrial arrhythmias
– Most significant in the presence of underlying heart disease
– Serious: atrial fibrillation can lead to the formation of clots in the heart
• Nodal arrhythmias
– May involve tachycardia and increased workload of the heart or bradycardia from heart block
• Ventricular arrhythmias
– Include premature ventricular contractions (PVCs), ventricular tachycardia, and ventricular fibrillation
|
Class |
Action |
Drugs |
|
I |
Sodium Channel Blockade |
|
|
IA |
Prolong repolarization |
Quinidine, procainamide, disopyramide |
|
IB |
Shorten repolarization |
Lidocaine, mexiletine, tocainide, phenytoin |
|
IC |
Little effect on repolarization |
Encainide, flecainide, propafenone |
|
II |
Beta-Adrenergic Blockade |
Propanolol, esmolol, acebutolol, l-sotalol |
|
III |
Prolong Repolarization (Potassium Channel Blockade; Other) |
Ibutilide, dofetilide, sotalol (d,l), amiodarone, bretylium |
|
IV |
Calcium Channel Blockade |
Verapamil, diltiazem, bepridil |
|
Miscellaneous |
Miscellaneous Actions |
Adenosine, digitalis, magnesium |
Indications
• To convert atrial fibrillation (AF) or flutter to normal sinus rhythm (NSR)
• To maintain NSR after conversion from AF or flutter
• When the ventricular rate is so fast or irregular that cardiac output is impaired
– Decreased cardiac output leads to symptoms of decreased systemic, cerebral, and coronary circulation
• When dangerous arrhythmias occur and may be fatal if not quickly terminated
– For example: ventricular tachycardia may cause cardiac arrest
Mechanism of Action
• Reduce automaticity (spontaneous depolarization of myocardial cells, including ectopic pacemakers)
• Slow conduction of electrical impulses through the heart
• Prolong the refractory period of myocardial cells (so they are less likely to be prematurely activated by adjacent cells
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