NEET MDS Synopsis
Meperidine
Pharmacology
Meperidine (Demerol)
Meperidine is a phenylpiperidine and has a number of congeners. It is mostly effective in the CNS and bowel
Produces analgesia, sedation, euphoria and respiratory depression.
Less potent than morphine, 80-100 mg meperidine equals 10 mg morphine.
Shorter duration of action than morphine (2-4 hrs).
Meperidine has greater excitatory activity than does morphine and toxicity may lead to convulsions.
Meperidine appears to have some atropine-like activity.
Does not constrict the pupils to the same extent as morphine.
Does not cause as much constipation as morphine.
Spasmogenic effect on GI and biliary tract smooth muscle is less pronounced than that produced by morphine.
Not an effective antitussive agent.
In contrast to morphine, meperidine increases the force of oxytocin-induced contractions of the uterus.
Often the drug of choice during delivery due to its lack of inhibitory effect on uterine contractions and its relatively short duration of action.
It has serotonergic activity when combined with monoamine oxidase inhibitors, which can produce serotonin toxicity (clonus, hyperreflexia, hyperthermia, and agitation)
Types of Removable Orthodontic Appliances
OrthodonticsTypes of Removable Orthodontic Appliances
Functional Appliances:
Purpose: Designed to modify the growth of the jaw
and improve the relationship between the upper and lower teeth.
Examples:
Bionator: Encourages forward positioning of the
mandible.
Frankel Appliance: Used to modify the position
of the dental arches and improve facial aesthetics.
Retainers:
Purpose: Used to maintain the position of teeth
after orthodontic treatment.
Types:
Hawley Retainer: A custom-made acrylic plate
with a wire framework that holds the teeth in position.
Essix Retainer: A clear, plastic retainer that
fits over the teeth, providing a more aesthetic option.
Space Maintainers:
Purpose: Used to hold space for permanent teeth
when primary teeth are lost prematurely.
Types:
Band and Loop: A metal band placed on an
adjacent tooth with a loop extending into the space.
Distal Shoe: A space maintainer used in the
lower arch to maintain space for the first molar.
Aligners:
Purpose: Clear plastic trays that gradually move
teeth into the desired position.
Examples:
Invisalign: A popular brand of clear aligners
that uses a series of custom-made trays to achieve tooth movement.
Expansion Appliances:
Purpose: Used to widen the dental arch,
particularly in cases of crossbite or narrow arches.
Examples:
Rapid Palatal Expander (RPE): A device that
applies pressure to the upper molars to widen the maxilla.
Components of Removable Orthodontic Appliances
Baseplate: The foundation of the appliance, usually
made of acrylic, which holds the other components in place.
Active Components: Springs, screws, or other mechanisms
that exert forces on the teeth to achieve movement.
Retention Components: Clasps or other features that
help keep the appliance securely in place during use.
Adjustable Parts: Some appliances may have adjustable
components to fine-tune the force applied to the teeth.
Indications for Use
Correction of Malocclusions: Removable appliances can
be used to address various types of malocclusions, including crowding,
spacing, and crossbites.
Space Maintenance: To hold space for permanent teeth
when primary teeth are lost prematurely.
Tooth Movement: To move teeth into desired positions,
particularly in growing patients.
Retention: To maintain the position of teeth after
orthodontic treatment.
Jaw Relationship Modification: To influence the growth
of the jaw and improve the relationship between the dental arches.
Advantages of Removable Orthodontic Appliances
Patient Compliance: Patients can remove the appliance
for eating, brushing, and social situations, which can improve compliance.
Hygiene: Easier to clean compared to fixed appliances,
reducing the risk of plaque accumulation and dental caries.
Flexibility: Can be adjusted or modified as treatment
progresses.
Less Discomfort: Generally, removable appliances are
less uncomfortable than fixed appliances, especially during initial use.
Aesthetic Options: Clear aligners and other aesthetic
appliances can be more visually appealing to patients.
Disadvantages of Removable Orthodontic Appliances
Compliance Dependent: The effectiveness of removable
appliances relies heavily on patient compliance; if not worn as prescribed,
treatment may be delayed or ineffective.
Limited Force Application: They may not be suitable for
complex tooth movements or significant skeletal changes.
Adjustment Period: Some patients may experience
discomfort or difficulty speaking initially.
Antihypertensives drugs -DIURETICS
Pharmacology
DIURETICS
The basis for the use of diuretics is to promote sodium depletion (and thereby water) which leads to a decrease in extracellular fluid volume.
An important aspect of diuretic therapy is to prevent the development of tolerance to other antihypertensive drugs.
TYPES OF DIURETICS
A. Thiazide Diuretics examples include chlorothiazide
hydrochlorothiazide
a concern with these drugs is the loss of potassium as well as sodium
B. Loop Diuretics (High Ceiling Diuretics) examples include
furosemide (Lasix)
bumetanide
these compounds produce a powerful diuresis and are capable of producing severe derangements of electrolyte balance
C. Potassium Sparing Diuretics examples include
triamterene
amiloride
spironolactone
unlike the other diuretics, these agents do not cause loss of potassium
Mechanism of Action
Initial effects: through reduction of plasma volume and cardiac output.
Long term effect: through decrease in total peripheral vascular resistance.
Advantages
Documented reduction in cardiovascular morbidity and mortality.
Least expensive antihypertensive drugs.
Best drug for treatment of systolic hypertension and for hypertension in theelderly.
Can be combined with all other antihypertensive drugs to produce synergetic effect.
Side Effects
Metabolic effects (uncommon with small doses): hypokalemia,hypomagnesemia, hyponatremia, hyperuricemia, dyslipidemia (increased total
and LDL cholesterol), impaired glucose tolerance, and hypercalcemia (with thiazides).
Postural hypotension.
Impotence in up to 22% of patients.
Considerations
- Moderate salt restriction is the key for effective antihypertensive effect of diuretics and for protection from diuretic - induced hypokalaemia.
- Thiazides are not effective in patients with renal failure (serum creatinine > 2mg /dl) because of reduced glomerular filtration rate.
- Frusemide needs frequent doses ( 2-3 /day ).Thiazides can be given once daily or every other day.
- Potassium supplements should not be routinely combined with thiazide or loop diuretics. They are indicated with hypokalemia (serum potassium < 3.5 mEq/L) especially with concomitant digitalis therapy or left ventricular hypertrophy.
- Nonsteroidal antiinflammatory drugs can antagonize diuretics effectiveness.
Special Indications
Diuretics should be the primary choice in all hypertensives.
They are indicated in:
- Volume dependent forms of hypertension: blacks, elderly, diabetic, renal and obese hypertensives.
- Hypertension complicated with heart failure.
- Resistant hypertension: loop diuretics in large doses are recommended.
- Renal impairment: loop diuretics
Neurons
PhysiologyNeurons :
Types of neurons based on structure:
a multipolar neuron because it has many poles or processes, the dendrites and the axon. Multipolar neurons are found as motor neurons and interneurons. There are also bipolar neurons with two processes, a dendrite and an axon, and unipolar neurons, which have only one process, classified as an axon.. Unipolar neurons are found as most of the body's sensory neurons. Their dendrites are the exposed branches connected to receptors, the axon carries the action potential in to the central nervous system.
Types of neurons based on function:
motor neurons - these carry a message to a muscle, gland, or other effector. They are said to be efferent, i.e. they carry the message away from the central nervous system.
sensory neurons - these carry a message in to the CNS. They are afferent, i.e. going toward the brain or spinal cord.
interneuron (ie. association neuron, connecting neuron) - these neurons connect one neuron with another. For example in many reflexes interneurons connect the sensory neurons with the motor neurons.
Alveolar bone (process)
Dental Anatomy
Alveolar bone (process)
1. The bone in the jaws that contains the teeth alveoli (sockets).
2. Three types of bone :
a. Cribriform plate (alveolar bone proper)
(1) Directly lines and forms the tooth socket. It is compact bone that contains many holes, allowing for the passage of blood vessels. It has no periosteum.
(2) Serves as the attachment site for PDL (Sharpey’s) fibers.
(3) The tooth socket is constantly being remodeled in response to occlusal forces. The bone laid down on the cribriform plate, which also provides attachment for PDL fibers, is known as bundle bone.
(4) It is radiographically known as the lamina dura.
b. Cortical (compact) bone
(1) Lines the buccal and lingual surfaces of the mandible and maxilla.
(2) Is typical compact bone with a periosteum and contains Haversian systems.
(3) Is generally thinner in the maxilla and thicker in the mandible, especially around the buccal area of the mandibular premolar and molar.
c. Trabecular (cancellous, spongy) bone
(1) Is typical cancellous bone containing Haversian systems.
(2) Is absent in the maxillary anterior teeth region.
3. Alveolar crest (septa)
a. The height of the alveolar crest is usually 1.5 to 2 mm below the CEJ junction.
b. The width is determined by the shape of adjacent teeth.
(1) Narrow crests—found between teeth with relatively flat surfaces.
(2) Widened crests—found between teeth with convex surfaces or teeth spaced apart.
Oxycodone
Pharmacology
Oxycodone
About equal potency to morphine. Very effective orally.
It is combined with aspirin or acetaminophen for the treatment of moderate pain and is available orally
Oxycodone is a semisynthetic compound derived from thebaine, with agonist activity primarily at mu receptors.
SELECTION OF SPRUE
Dental Materials
SELECTION OF SPRUE
1 . DIAMETER :
It should be approximately the same size of the thickest portion of the wax pattern .
Too small sprue diameter suck back porosity results .
2 . SPRUE FORMER ATTACHMENT :
Sprue should be attached to the thickest portion of the wax pattern .
It should be Flared for high density alloys & Restricted for low density alloys .
3 . SPRUE FORMER POSITION
Based on the
1. Individual judgement .
2. Shape & form of the wax pattern .
Patterns may be sprued directly or indirectly .
Indirect method is commonly used
ANTICHOLINERGIC DRUGS
Pharmacology
ANTICHOLINERGIC DRUGS
Blocks the action of Ach on autonomic effectors.
Classification
Natural Alkaloids - Atropine. Hyoscine
Semi-synthetic deriuvatives:- Homatropine, Homatropine methylbromide, Atropine methonitrate.
Synthetic compounds
(a) Mydriatics - Cyclopentolate. Tropicamide.
(b) Antisecretory - Antispasmodics - Propantha1ine. Oxy-phenonium, Pirenzipine.
c) Antiparkinsonism- Benzotopine, Ethopropazine, Trihexyphenidyl, Procyclidine, Biperiden
Other drugs with anticholinergic properties • Tricyclic Antidepressants • Phenothiazines • Antihistaminics • Disopyramide
MUSCARINIC RECEPTORS SUBTYPES & ANTAGONISTS
• M 1 Antagonists – Pirenzepine, Telenzepine, dicyclomine, trihexyphenidyl
• M 2 Antagonists – Gallamine, methoctramine
• M 3 Antagonists – Darifenacin, solifenacin, oxybutynin, tolterodine
Pharmacological Actions
CNS - stimulation of medullary centres like vagal. respiratory. vasomotor and inhibition of vestibular excitation and has anti-motion sickness properties.
CVS - tachycardia.
Eye - mydriasis
Smooth muscles - relaxation of the muscles receiving parnsympathetic motor innervation.
Glands - decreased secretion of sweat and salivary glands
Body Temperature - is increased as there is stimulation of temperature regulating centre.
Respiratory System- Bronchodilatation & decrease in secretions. For COPD or Asthma - antimuscarinic drugs are effective
GIT - Pirenzepine & Telenzepine - decrease gastric secretion with lesser side effects.