NEET MDS Synopsis
Drugs Used in Diabetes -Insulin
Pharmacology
Insulin
Insulin is only given parenterally (subcutaneous or IV) Various preparations have different durations of action
Preparation
Onset (hrs)
Peak (hrs)
Duration (hrs)
Lispro (rapid-acting)
15 min
0.5-1.5
3-4
Regular (short-acting)
0.5-1
2-4
5-7
NPH (intermediate)
1-2
6-12
18-24
Glargine (long-acting)
1
None
>24
Mechanism
bind transmembrane insulin receptor
activate tyrosine kinase
phosphorylate specific substrates in each tissue type
liver
↑ glycogenesis
store glucose as glycogen
muscle
↑ glycogen and protein synthesis
↑ K+ uptake
fat
increase triglyceride storage
Clinical use
type I DM
type II DM
life-threatening hyperkalemia
increases intracellular K+
stress-induced hyperglycemia
Toxicity
hypoglycemia
hypersensitivity reaction (very rare)
Insulin Synthesis
first generated as preproinsulin with an A chain and B chain connected by a C peptide.
c-peptide is cleaved from proinsulin after packaging into vesicles leaving behind the A and B chains
Spinal Anaesthesia
AnaesthesiaSpinal Anesthesia
A. Anatomy
Spinal anesthesia targets the spinal cord, which arises from the foramen magnum
and extends to the conus medullaris, typically ending around the third lumbar
vertebrae (L3) in adults. The spinal column is protected by three layers: the
dura mater, arachnoid mater, and pia mater. The subarachnoid space, where the
spinal anesthetic is administered, contains cerebrospinal fluid (CSF), spinal
nerves, and the arachnoid and pial vessels. The arachnoid membrane provides
significant resistance to drug diffusion, accounting for approximately 90% of
the barrier.
The epidural space lies outside the dura mater and is bounded by the ligamentum
flavum, lamina, and spinous processes. It is important to distinguish between
the epidural and subarachnoid spaces, as the needle placement determines the
type of anesthesia administered.
Key anatomic landmarks for spinal anesthesia include the iliac crests, which can
be used to approximate the L4-L5 interspace. The spinal needle is commonly
inserted at the L3 or L4 level in adults to avoid the termination of the spinal
cord.
B. Indications
1. Lower abdominal and pelvic surgeries: Spinal anesthesia is suitable for
surgeries below the umbilicus, such as hernia repairs, gynecological and
urological procedures.
2. Lower extremity surgeries: This includes orthopedic procedures and lower limb
surgeries.
3. Cesarean sections: It provides adequate analgesia and muscle relaxation while
allowing the mother to remain awake and participate in the birth.
C. Contraindications
Absolute contraindications:
1. Patient refusal or inability to cooperate and maintain a still position.
2. Coagulation disorders or use of anticoagulants, which increase the risk of
spinal hematoma.
3. Local infection at the injection site.
Relative contraindications:
1. Sepsis: Due to the risk of spreading infection to the central nervous system.
2. Neurological conditions: Such as myelitis, which can be exacerbated by
invasive procedures.
3. Intracranial hypertension: As spinal anesthesia can cause a sudden drop in
systemic vascular resistance and increase intracranial pressure.
4. Severe spinal or spinal cord deformities: These may lead to complications in
needle placement and drug distribution.
5. Cardiovascular conditions: Stenotic heart valve lesions and severe
hypertrophic cardiomyopathy can be poorly tolerated due to the hemodynamic
changes associated with spinal anesthesia.
6. Lack of anesthesiologist experience: This may increase the risk of
complications.
D. Equipment
1. Patient monitors: ECG for heart rhythm monitoring, pulse oximeter for oxygen
saturation, and a blood pressure cuff to assess circulation.
2. Resuscitation equipment: Oxygen supply, bag and mask for ventilation, and
suction to clear the airway if needed.
3. Sterile environment: Sterile gloves, mask, gown (if required), and a clean
field are essential to prevent infection.
4. Intravenous access: To administer fluids and medications during the
procedure.
5. Sterile prep solution: Typically Betadine or a non-iodine alternative for
skin preparation.
6. Spinal needle: Small gauge (24-26 gauge) for minimizing trauma.
7. Sterile drapes: To maintain the sterility of the area.
8. Local anesthetic: For skin infiltration to reduce pain during the spinal
block.
9. Syringes: A small syringe for local anesthetic and a 3-5 mL syringe for the
spinal anesthetic agent.
10. Anesthetic agent: Typically a local anesthetic with or without additives
like epinephrine or opioids to prolong the block and enhance analgesia.
11. Bandage: For securing the needle site post-procedure
Ciprofloxacin
Pharmacology
Ciprofloxacin : Ciprofloxacin is bactericidal and its mode of action depends on blocking of bacterial DNA replication by binding itself to an enzyme called DNA gyrase
Ciprofloxacin is a broad-spectrum antibiotic that is active against both Gram-positive and Gram-negative bacteria.
Enterobacteriaceae, Vibrio, Hemophilus influenzae, Neisseria gonorrhoeae
Neisseria menigitidis, Moraxella catarrhalis, Brucella, Campylobacter,
Mycobacterium intracellulare, Legionella sp., Pseudomonas aeruginosa,
Bacillus anthracis - that causes anthrax
Weak activity against: Streptococcus pneumoniae,
No activity against: Bacteroides, Enterococcus faecium, Ureaplasma urealyticum and others
It is contraindicated in children, pregnancy, and epilepsy.
Ciprofloxacin can cause photosensitivity reactions and can elevate plasma
theophylline levels to toxic values. It can also cause constipation and sensitivity to caffeine.
Dosage in respiratory infections is 500-1500 mg a day in 2 doses.
Stimulants
Pharmacology
Stimulants:
Amphetamines: amphetamine is a substrate of serotonin and NE uptake transporters so in cytoplasm, it competes for transport into storage vesicles → ↑ [ ] in cytoplasm then excess amines bind to membrane transporter and are transported out of cell
Drugs:
a. Dextroamphetamine: psychomotor stimulant (↓ fatigue), short-term weight loss, prevents narcolepsy
b. Methylphenidate (Ritalin): prevents narcolepsy, treatment for ADD and ADHD
c. Methamphetamine: psychomotor stimulant, abused widely (cheap, easy to make)
Side effects:
a. CNS: euphoria, anxiety, agitation, delirium, paranoia, panic, suicidal/homicidal impulses, psychoses, tolerance (develops rapidly to most CNS effects), physical dependence (not clinically relevant)
b. CV: headache, chills, arrhythmias and HTN (may be fatal)
OCCLUSION AND DENTAL DEVELOPMENT-Stages-Mixed Dentition Period
Dental Anatomy
Mixed Dentition Period.
-Begins with the eruption of the first permanent molars distal to the second deciduous molars. These are the first teeth to emerge and they initially articulate in an 'end-on' (one on top of the other) relationship.
-On occasion, the permanent incisors spread out due to spacing. In the older literature, is called by the 'ugly duckling stage.' With the eruption of the permanent canines, the spaces often will close.
-Between ages 6 and 7 years of age there are:
20 deciduous teeth
4 first permanent molars
28 permanent tooth buds in various states of development
Bases
Conservative DentistryBases in Restorative DentistryBases are an essential component in restorative dentistry, serving as a
thicker layer of material placed beneath restorations to provide additional
protection and support to the dental pulp and surrounding structures. Below is
an overview of the characteristics, objectives, and types of bases used in
dental practice.
1. Characteristics of BasesA. Thickness
Typical Thickness: Bases are generally thicker than
liners, typically ranging from 1 to 2 mm. Some bases may be
around 0.5 to 0.75 mm thick.
B. Functions
Thermal Protection: Bases provide thermal insulation to
protect the pulp from temperature changes that can occur during and after
the placement of restorations.
Mechanical Support: They offer supplemental mechanical
support for the restoration by distributing stress on the underlying dentin
surface. This is particularly important during procedures such as amalgam
condensation, where forces can be applied to the restoration.
2. Objectives of Using BasesThe choice of base material and its application depend on the Remaining
Dentin Thickness (RDT), which is a critical factor in determining the
need for a base:
RDT > 2 mm: No base is required, as there is sufficient
dentin to protect the pulp.
RDT 0.5 - 2 mm: A base is indicated, and the choice of
material depends on the restorative material being used.
RDT < 0.5 mm: Calcium hydroxide (Ca(OH)₂) or Mineral
Trioxide Aggregate (MTA) should be used to promote the formation of
reparative dentin, as the remaining dentin is insufficient to provide
adequate protection.
3. Types of BasesA. Common Base Materials
Zinc Phosphate (ZnPO₄): Known for its good mechanical
properties and thermal insulation.
Glass Ionomer Cement (GIC): Provides thermal protection
and releases fluoride, which can help in preventing caries.
Zinc Polycarboxylate: Offers good adhesion to tooth
structure and provides thermal insulation.
B. Properties
Mechanical Protection: Bases distribute stress
effectively, reducing the risk of fracture in the restoration and protecting
the underlying dentin.
Thermal Insulation: Bases are poor conductors of heat
and cold, helping to maintain a stable temperature at the pulp level.
Comparisons of primary and permanent teeth:
Pedodontics
1. Crown Dimensions
Primary Anterior Teeth: The crowns of primary anterior
teeth (incisors and canines) are characterized by a wider mesiodistal
dimension and a shorter incisocervical height compared to their permanent
counterparts. This means that primary incisors are broader from side to side
and shorter from the biting edge to the gum line, giving them a more squat
appearance.
Primary Molars: The crowns of primary molars are also
shorter and narrower in the mesiodistal direction at the cervical third
compared to permanent molars. This results in a more constricted appearance
at the base of the crown, which is important for accommodating the
developing permanent teeth.
2. Root Structure
Primary Anterior Teeth: The roots of primary anterior
teeth taper more rapidly than those of permanent anterior teeth. This rapid
tapering allows for a more pronounced root system that is essential for
anchoring the teeth in the softer bone of children’s jaws.
Primary Molars: In contrast, the roots of primary molars
are longer and more slender than those of permanent molars. This elongation
and slenderness provide stability while also allowing for the necessary
space for the developing permanent teeth beneath them.
3. Enamel Characteristics
Enamel Rod Orientation: In primary teeth, the enamel
rods in the gingival third slope occlusally (toward the biting surface)
rather than cervically (toward the root) as seen in permanent teeth. This
unique orientation can influence the way primary teeth respond to wear and
decay.
Thickness of Enamel: The enamel on the occlusal surfaces
of primary molars is of uniform thickness, measuring approximately 1 mm. In
contrast, the enamel on permanent molars is thicker, averaging around 2.5
mm. This difference in thickness can affect the durability and longevity of
the teeth.
4. Surface Contours
Buccal and Lingual Surfaces: The buccal and lingual
surfaces of primary molars are flatter above the crest of contour compared
to permanent molars. This flatter contour can influence the way food is
processed and how plaque accumulates on the teeth.
5. Root Divergence
Primary Molars: The roots of primary molars are more
divergent relative to their crown width compared to permanent molars. This
divergence is crucial as it allows adequate space for the developing
permanent dentition, which is essential for proper alignment and spacing in
the dental arch.
6. Occlusal Features
Occlusal Table: The occlusal table of primary molars is
narrower in the faciolingual dimension. This narrower occlusal surface,
combined with shallower anatomy, results in shorter cusps, less pronounced
ridges, and shallower fossae. These features can affect the functional
aspects of chewing and the overall occlusion.
Mesial Cervical Ridge: Primary molars exhibit a
prominent mesial cervical ridge, which serves as a distinguishing feature
that helps in identifying the right and left molars during dental
examinations.
7. Root Characteristics
Root Shape and Divergence: The roots of primary molars
are not only longer and more slender but also extremely narrow mesiodistally
and broad lingually. This unique shape contributes to their stability while
allowing for the necessary divergence and minimal curvature. Additionally,
primary molars typically have little or no root trunk, which is a stark
contrast to the more complex root structures of permanent molars.
Control of processes in the stomach
PhysiologyControl of processes in the stomach:
The stomach, like the rest of the GI tract, receives input from the autonomic nervous system. Positive stimuli come from the parasympathetic division through the vagus nerve. This stimulates normal secretion and motility of the stomach. Control occurs in several phases:
Cephalic phase stimulates secretion in anticipation of eating to prepare the stomach for reception of food. The secretions from cephalic stimulation are watery and contain little enzyme or acid.
Gastric phase of control begins with a direct response to the contact of food in the stomach and is due to stimulation of pressoreceptors in the stomach lining which result in ACh and histamine release triggered by the vagus nerve. The secretion and motility which result begin to churn and liquefy the chyme and build up pressure in the stomach. Chyme surges forward as a result of muscle contraction but is blocked from entering the duodenum by the pyloric sphincter. A phenomenon call retropulsion occurs in which the chyme surges backward only to be pushed forward once again into the pylorus. The presence of this acid chyme in the pylorus causes the release of a hormone called gastrin into the bloodstream. Gastrin has a positive feedback effect on the motility and acid secretion of the stomach. This causes more churning, more pressure, and eventually some chyme enters the duodenum.
Intestinal phase of stomach control occurs. At first this involves more gastrin secretion from duodenal cells which acts as a "go" signal to enhance the stomach action already occurring. But as more acid chyme enters the duodenum the decreasing pH inhibits gastrin secretion and causes the release of negative or "stop" signals from the duodenum.
These take the form of chemicals called enterogastrones which include GIP (gastric inhibitory peptide). GIP inhibits stomach secretion and motility and allows time for the digestive process to proceed in the duodenum before it receives more chyme. The enterogastric reflex also reduces motility and forcefully closes the pyloric sphincter. Eventually as the chyme is removed, the pH increases and gastrin and the "go" signal resumes and the process occurs all over again. This series of "go" and "stop" signals continues until stomach emptying is complete.