NEET MDS Lessons
Pharmacology
Levofloxacin
Levofloxacin is effective against a number of gram-positive and gram-negative bacteria. Because of its broad spectrum of action, levofloxacin is frequently prescribed in hospitals for pulmonary infections
Hypothalamic - Pituitary Drugs
Somatropin
Growth hormone (GH) mimetic
Mechanism
agonist at GH receptors
increases production of insulin growth factor-1 (IGF-1)
Clinical use
GH deficiency
increase adult height for children with conditions associated with short stature
Turner syndrome
wasting in HIV infection
short bowel syndrome
Toxicity
scoliosis
edema
gynecomastia
increased CYP450 activity
Octreotide
Somatostatin mimetic
Mechanism
agonist at somatostatin receptors
Clinical use
acromegaly
carcinoid
gastrinoma
glucagonoma
acute esophageal variceal bleed
Toxicity
GI upset
gallstones
bradycardia
Oxytocin
Mechanism
agonist at oxytocin receptor
Clinical use
stimulation of labor
uterine contractions
control of uterine hemorrhage after delivery
stimulate milk letdown
Toxicity
fetal distress
abruptio placentae
uterine rupture
Desmopressin
ADH (vasopressin) mimetic
Mechanism
agonist at vasopressin V2 receptors
Clinical use
central (pituitary) diabetes insipidus
hemophilia A (factor VIII deficiency)
increases availability of factor VIII
von Willebrand disease
increases release of von Willebrand factor from endothelial cells
Toxicity
GI upset
headache
hyponatremia
allergic reaction
Patient positioning
The most common medical emergency encountered in the dental office setting is syncope. So patients in the supine or semi-supine position to improve venous return and cerebral blood flow provided that the position is tolerated by the patient and is appropriate for their medical condition.
Examples of calculations of doses of vasoconstrictors
Ratio concentrations represent grams per millilitre
1:100,000 = 0.01 mg/mL or 10 µg/mL
1:200,000 = 0.005 mg/mL or 5 µg/mL
1:50,000 = 0.02 mg/mL or 20 µg/mL
1 cartridge of epinephrine 1:200,000 = 9 µg
1 cartridge of epinephrine 1:100,000 = 18 µg
1 cartridge of epinephrine 1:50,000 = 36 µg
1 cartridge of levonordefrin 1:20,000 = 90 µg
Routes of Drug Administration
Intravenous
- No barriers to absorption since drug is put directly into the blood.
- There is a very rapid onset for drugs administered intravenously. This can be advantagous in emergency situations, but can also be very dangerous.
- This route offers a great deal of control in respect to drug levels in the blood.
- Irritant drugs can be administer by the IV route without risking tissue injury.
- IV drug administration is expensive, inconvenient and more difficult than administration by other routes.
- Other disadvantages include the risk of fluid overload, infection, and embolism. Some drug formulations are completely unsafe for use intravenously.
Intramuscular:
- Only the capillary wall separates the drug from the blood, so there is not a significant barrier to the drug's absorption.
- The rate of absorption varies with the drug's solubility and the blood flow at the site of injection.
- The IM route is uncomfortable and inconvenient for the patient, and if administered improperly, can lead to tissue or nerve damage.
Subcutaneous
Same characteristics as the IM route.
Oral
- Two barriers to cross: epithelial cells and capillary wall. To cross the epithelium, drugs have to pass through the cells.
- Highly variable drug absorption influenced by many factors: pH, drug solubility and stability, food intake, other drugs, etc.
- Easy, convenient, and inexpensive. Safer than parenteral injection, so that oral administration is generally the preferred route.
- Some drugs would be inactivated by this route
- Inappropriate route for some patients.
- May have some GI discomfort, nausea and vomiting.
- Types of oral meds = tablets, enteric-coated, sustained-release, etc.
- Topical, Inhalational agents, Suppositories
Propofol -Intravenous Anesthetics
- A nonbarbiturate anesthetic
- It is very lipid-soluble, acts rapidly and has a short recovery time.
- It is associated with less nausea and vomiting than some of the other IV anesthetics.
- Propofol is very similar to thiopental in its effects on the cardiorespiratory system.
- It does not have any analgesic properties but lowers the dose of opioid needed when the two agents are used in combination.
- The most significant adverse cardiovascular effect associated with propofol administration is hypotension. It should be used with caution in patients with cardiac disease.
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
|
|
Infiltration |
Nerve block |
||
|
|
Pulpal |
Soft tissue |
Pulpal |
Soft tissue |
|
Short |
30 min |
2-3 hrs |
45 min |
2-3 hrs |
|
Intermediate |
60 min |
2-3 hrs |
75-90 min |
3-4 hrs |
|
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