NEET MDS Lessons
Pharmacology
Cephalosporins
Produced semisynthetically by chemical attachment of side chains to 7-aminocephalosporanic acid. Same mode of action , same resistance mech.
But tend to be more resistant than penicillins to certain beta –lactamases .
GENERATION BASED ON :
-- BACTERIAL SUSCEPTIBILITY PATTERNS
-- RESISTANCE TO BETA –LACTAMASES
--NOT EFFECTIVE AGAINST -MRSA , L. MONOCYTOGENES , C. DIFFICLE , ENTEROCOCCI
First Generation
Parentral
- CEPHALOTHIN
- CEFAZOLIN
Oral
- CEPHALEXIN
- CEPHRADINE
- CEFADROXIL
Second Generation
Parentral
CEFUROXIME
CEFOXITIN
Oral
CEFACLOR
CEFUROXIME AXETIL
Third Generation
Parentral
CEFOTAXIME
CEFTIZOXIME
CEFTRIAXONE
CEFTAZIDIME
CEFOPERAZONE
Oral
CEFIXIME
CEFPODOXIME
CEFDINIR
CEFTIBUTEN
Fourth Generation
Parentral
CEFEPIME
CEFPIROME
SGLT-2 Inhibitors
canagliflozin
empagliflozin
Mechanism
glucose is reabsorbed in the proximal tubule of the nephron by the sodium-glucose cotransporter 2 (SGLT2)
SGLT2-inhibitors lower serum glucose by increasing urinary glucose excretion
the mechanism of action is independent of insulin secretion or action
Clinical use
type II DM
Celecoxib
is a highly selective COX-2 inhibitor and primarily inhibits this isoform of cyclooxygenase, whereas traditional NSAIDs inhibit both COX-1 and COX-2. Celecoxib is approximately 10-20 times more selective for COX-2 inhibition over COX-1.
Being a sulphonamide can cause skin rash & hypersensitivity rxn., occasional oedema& HT.
Indication
Osteoarthritis ( 100‐200mg BID ) , rheumatoid arthritis, dysmenorrhea, acute gouty attacks, acute musculoskeletal pain.
SYMPATHOMIMETICS
β2 -agonists are invariably used in the symptomatic treatment of asthma.
Epinephrine and ephedrine are structurally related to the catecholamine norepinephrine, a neurotransmitter of the adrenergic nervous system
Some of the important β 2 agonists like salmeterol, terbutaline and salbutamol are invariably used as bronchodilators both oral as well as
aerosol inhalants
SALBUTAMOL
It is highly selective β2 -adrenergic stimulant h-aving a prominent bronchodilator action.
It has poor cardiac action compared to isoprenaline.
TERBUTALINE
It is highly selective β2 agonist similar to salbutamol, useful by oral as well as inhalational route.
SALMETEROL
Salmeterol is long-acting analogue of salbutamol
BAMBUTEROL
It is a latest selective adrenergic β2 agonist with long plasma half life and given once daily in a dose of 10-20 mg orally.
METHYLXANTHINES (THEOPHYLLINE AND ITS DERIVATIVES)
THEOPHYLLINE
Theophylline has two distinct action:
smooth muscle relaxation (i.e. bronchodilatation) and suppression of the response of the airways to stimuli (i.e. non-bronchodilator prophylactic effects).
ANTICHOLINERGICS
Anticholinergics, like atropine and its derivative ipratropium bromide block cholinergic pathways that cause airway constriction.
MAST CELL STABILIZERS
SODIUM CROMOGLYCATE
It inhibits degranulation of mast cells by trigger stimuli.
It also inhibits the release of various asthma provoking mediators e.g. histamine, leukotrienes, platelet activating factor (PAF) and interleukins (IL’s) from mast cell
KETOTIFEN
It is a cromolyn analogue. It is an antihistaminic (H1 antagonist) and probably inhibits airway inflammation induced by platelet activating factor (PAF) in primate.
It is not a bronchodilator. It is used in asthma and symptomatic relief in atopic dermatitis, rhinitis, conjunctivitis and urticaria.
LEUKOTRIENE PATHWAY INHIBITORS
MONTELUKAST
It is a cysteinyl leukotriene receptor antagonist indicated for the management of persistent asthma.
Monoamine oxidase inhibitors (MAOIs)
e.g. phenelzine, tranylcypromine, moclobemide
- Belong to first generation antidepressants with TCAs
- Most MAOIs irreversibly inhibit the intraneuronal catabolism of norepinephrine and serotonin by MAO-A and MAO-B
- increase brain levels of noradrenaline and 5-HT
- Moclobemide causes selective, reversible inhibition of MAO-A
DRUG INTERACTIONS
Hypertensive crises similar to cheese reaction with OTC cough/cold preparations containing indirect-sympathomimetics
e.g. ephedrine
- Other antidepressants should not be started at least 2 weeks after stopping MAOIs and vice versa due to risk of serotonin syndrome
- Similar interaction with pethidine
ADVERSE DRUG REACTIONS
- Antimuscarinic side effects (e.g. dry mouth, blurred vision, urinary retention)vision, urinary retention)
- Excessive central stimulation causes tremors, excitement and insomnia
- Postural hypotension
- Increased appetite with weight gain
Piroxicam:
Half‐life of 45 hrs. Once‐daily dosing. Delay onset of action.
High doses inhibits PMN migration, decrease oxygen radical production, inhibits lymphocyte function.
used to relieve the symptoms of arthritis, primary dysmenorrhoea, pyrexia; and as an analgesic,non-selective cyclooxygenase (COX) inhibitor
The risk of adverse side efects is nearly ten times higher than with other NSAIDs. Peptic ulcer (9.5 higher)
Dissociation constants
|
Local anesthetic |
pKa |
% of base(RN) at pH 7.4 |
onset of action(min) |
|
Lidocaine |
7.8 |
29 |
2-4 |
|
Bupivacaine |
8.1 |
17 |
5-8 |
|
Mepivacaine |
7.7 |
33 |
2-4 |
|
Prilocaine |
7.9 |
25 |
2-4 |
|
Articaine |
7.8 |
29 |
2-4 |
|
Procaine |
9.1 |
2 |
14-18 |
|
Benzocaine |
3.5 |
100 |
- |