NEET MDS Synopsis
Methadone
Pharmacology
Methadone
Pharmacology and analgesic potency similar to morphine.
Very effective following oral administration.
Longer duration of action than morphine due to plasma protein binding (t1/2 approximately 25 hrs).
Used in methadone maintenance programs for drug addicts and for opiate withdrawal. Opiate withdrawal is more prolonged but is less intense than it is following morphine or heroin.
LIPOPROTIENS
Biochemistry
LIPOPROTIENS
Lipoproteins Consist of a Nonpolar Core & a Single Surface Layer of Amphipathic Lipids
The nonpolar lipid core consists of mainly triacylglycerol and cholesteryl ester and is surrounded by a single surface layer of amphipathic phospholipid and cholesterol molecules .These are oriented so that their polar groups face outward to the aqueous medium. The protein moiety of a lipoprotein is known as an apolipoprotein or apoprotein,constituting nearly 70% of some HDL and as little as 1% of Chylomicons. Some apolipoproteins are integral and cannot be removed, whereas others can be freely transferred to other lipoproteins.
There re five types of lipoproteins, namely chylomicrons, very low density lipoproteins(VLDL) low density lipoproteins (LDL), high density Lipoproteins (HDL) and free fatty acid-albumin complexes.
Gastric acid neutralizers (antacids)
Pharmacology
Gastric acid neutralizers (antacids)
Antacids act primarily in the stomach and are used to prevent and treat peptic ulcer. They are also used in the treatment of Reflux esophagitis and Gastritis.
Mechanism of action:
Antacids are alkaline substances (weak bases) that neutralize gastric acid (hydrochloric acid) they react with hydrochloric acid in the stomach to produce neutral or less acidic or poorly absorbed products and raise the pH of stomach secretion.
Antacids are divided into systemic and non-systemic.
• Systemic antacids (e.g. sodium bicarbonate) are highly absorbed into systemic circulation and enter body fluids. Therefore, they may alter acid–base balance. They can be used in the treatment of metabolic acidosis.
Non-systemic: they do not alter acid–base balance significantly, because they are not well-absorbed into the systemic circulation. They are used as gastric antacids; and include:
• Magnesium compounds such as magnesium hydroxide and magnesium sulphate MgS2O3. They have relatively high neutralizing capacity, rapid onset of action, however, they may cause diarrhoea and hypermagnesemia.
• Aluminium compounds such as aluminium hydroxide. Generally, these have low neutralizing capacity, slow onset of action but long duration of action. They may cause constipation.
• Calcium compounds such as. These are highly effective and have a rapid onset of action but may cause hypersecretion of acid (acid - rebound) and milk-alkali syndrome (hence rarely used in peptic ulcer disease).
Therefore, the most commonly used antacids are mixtures of aluminium hydroxide and magnesium hydroxide .
Gingival Crevicular Fluid
PeriodontologyGingival Crevicular Fluid (GCF)
Gingival crevicular fluid is an inflammatory exudate found in the gingival
sulcus. It plays a significant role in periodontal health and disease.
A. Characteristics of GCF
Glucose Concentration: The glucose concentration in GCF
is 3-4 times greater than that in serum, indicating
increased metabolic activity in inflamed tissues.
Protein Content: The total protein content of GCF is
much less than that of serum, reflecting its role as an inflammatory
exudate.
Inflammatory Nature: GCF is present in clinically
normal sulci due to the constant low-grade inflammation of the gingiva.
B. Drugs Excreted Through GCF
Tetracyclines and Metronidazole: These antibiotics are
known to be excreted through GCF, making them effective for localized
periodontal therapy.
C. Collection Methods for GCF
GCF can be collected using various techniques, including:
Absorbing Paper Strips/Blotter/Periopaper: These strips
absorb fluid from the sulcus and are commonly used for GCF collection.
Twisted Threads: Placing twisted threads around and
into the sulcus can help collect GCF.
Micropipettes: These can be used for precise collection
of GCF in research settings.
Intra-Crevicular Washings: Flushing the sulcus with a
saline solution can help collect GCF for analysis.
Titration of a weak acid with a strong base
Biochemistry
Titration of a weak acid with a strong base
• A weak acid is mostly in its conjugate acid form
• When strong base is added, it removes protons from the solution, more and more acid is in the conjugate base form, and the pH increases
• When the moles of base added equals half the total moles of acid, the weak acid and its conjugate base are in equal amounts. The ratio of CB / WA = 1 and according to the HH equation, pH = pKa + log(1) or pH = pKa.
• If more base is added, the conjugate base form becomes greater till the equivalance point when all of the acid is in the conjugate base form.
Prostaglandines
Pharmacology
Prostaglandines:
Every cell in the body is capable of synthesizing one or more types of PGS. The four major group of PGs are E, F, A, and B.
Pharmacological actions:
stimulation of cyclicAMP production and calcium use by various cells
CVS
PGE2 acts as vasodilator; it is more potent hypotensive than Ach and histamine
Uterous
PGE2 and PGF2α Contract human uterus
Bronchial muscle
PGF2α and thromboxan A2 cause bronchial muscle contraction.
PGE2 & PGI2 cause bronchial muscle dilatation
GIT: PGE2 and PGF2α cause colic and watery diarrhoea
Platelets
Thromboxan A2 is potent induce of platelets aggregation
Kidney
PGE2 and PGI2 increase water, Na ion and K ion excretion (act as diuresis) that cause renal vasodilatation and inhibit
tubular reabsorption
USE
PGI2: Epoprostenol (inhibits platelets aggregation)
PGE1: Alprostadil (used to maintain the potency of arterioles in neonates with congenital heart defects).
PGE2: Dinoproste (used as pessaries to induce labor)
Synthetic analogue of PGE1: Misoprostol (inhibit the secretion of HCl).
METAPLASIA
General Pathology
METAPLASIA
A reversible replacement of one type of adult tissue by another type of tissue. It is usually an adaptive substitution to a. cell type more suited to an environment, often at the cost of specialised function.
(1) Epithelial metaplasia:
Squamous metaplasia. This is the commoner type of metaplasia and is seen in:
Tracheobronchial lining in chronic smokers and in bronchiectasis.
In Vitamin A deficiency.
Columnar metaplasia:
Intestinalisation of gastric mucosa in chronic gastritis.
(2) Connective tissue metaplasia:
Osseous-Metaplasia in :
Scars.
Myositis ossificans
Myeloid metaplasia in liver and spleen.
Ketamine
Pharmacology
Ketamine
- Causes a dissociative anesthesia.
- Is similar to but less potent than phencyclidine.
- Induces amnesia, analgesia, catalepsy and anesthesia, but does not induce convulsions.
- The principal disadvantage of ketamine is its adverse psychic effects during emergence from anesthesia. These include: hallucinations, changes in mood and body image.
- During anesthesia, many of the protective reflexes are maintained, such as laryngeal, pharyngeal, eyelid and corneal reflexes.
- Muscle relaxation is poor.
- It is not indicated for intracranial operations because it increases cerebrospinal fluid pressure.
- Respiration is well maintained.
- Arterial blood pressure, cardiac output, and heart rate are all elevated.