NEET MDS Lessons
Pharmacology
Aminoglycoside
Aminoglycosides are a group of antibiotics that are effective against certain types of bacteria. They include amikacin, gentamicin, kanamycin, neomycin, netilmicin, paromomycin, streptomycin, and tobramycin. Those which are derived from Streptomyces species
Aminoglycosides work by binding to the bacterial 30S ribosomal subunit, causing misreading of t-RNA, leaving the bacterium unable to synthesize proteins vital to its growth.
Aminoglycosides are useful primarily in infections involving aerobic, Gram-negative bacteria, such as Pseudomonas, Acinetobacter, and Enterobacter. In addition, some mycobacteria, including the bacteria that cause tuberculosis, are susceptible to aminoglycosides. Streptomycin was the first effective drug in the treatment of tuberculosis, though the role of aminoglycosides such as streptomycin and amikacin have been eclipsed (because of their toxicity and inconvenient route of administration) except for multiple drug resistant strains.
Infections caused by Gram-positive bacteria can also be treated with aminoglycosides, but other types of antibiotics are more potent and less damaging to the host. In the past the aminoglycosides have been used in conjunction with penicillin-related antibiotics in streptococcal infections for their synergistic effects, particularly in endocarditis.
Because of their potential for ototoxicity and renal toxicity, aminoglycosides are administered in doses based on body weight. Blood drug levels and creatinine are monitored during the course of therapy.
There is no oral form of these antibiotics: they are generally administered intravenously, though some are used in topical preparations used on wounds.
Aminoglycosides are mostly ineffective against anaerobic bacteria, fungi and viruses.
BradyKinin
An endogenous vasodilator occurring in blood vessel walls.
At least two distinct receptor types, B1 and B2, appear to exist for BradyKinin
Roles of bradykinin:
1) Mediator of inflammation and pain.
2) Regulation of microcirculation.
3) Their production is interrelated with clotting and fibrinolysin systems.
4) Responsible for circulatory change after birth.
5) Involved in shock and some immune reactions.
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)
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.
Methicillin
Methicillin is an antibiotic related to penicillin and other beta-lactam containing antibiotics. It is often used to treat infections caused by bacteria carrying an antibiotic resistance, e.g., staphylococci. As methicillin is deactivated by gastric acid, it has to be administered by injection.
Uses Methicillin serves a purpose in the laboratory to determine antibiotic sensitivity in microbiological culture.
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
Methyl salicylate
also known as oil of wintergreen, betula oil, methyl ester) is a natural product of many species of plants Structurally, it is methylated salicylic acid It is used as an ingredient in deep heating rubs