Term | Definition |
allopurinol | <synthesis of uric acid by competitive inhibition of xanthine oxidase. Some inhibition of de novo purine synthesis.Converted to alloxanthine by xanthine oxidase,is effective noncompetitive inhibitor of the enzyme&produces most of therapeutic effect. |
methotrexate | Immunomodulator and inhibitor of tetrahydrofolate
dehydrogenase, thus preventing formation of
tetrahydrofolate that is necessary for synthesis of
thymidylate, an essential component of DNA. |
cetirizine | Competes with histamine for the normal H1-receptor
sites on effector cells of the gastrointestinal tract, blood
vessels and respiratory tract. Penetrates CNS less well
than chlorpheniramine so less sedating. |
dexamethasone | Binds with high affinity to specific cytoplasmic receptors to produce inhibition of leukocyte infiltration at the site of
inflammation, interference in the function of mediators of inflammatory response, and suppression of humoral immune responses |
charcoal, activated | Adsorbs several drugs and toxins, and used in treatment of poisoning with certain agents |
amoxicillin + clavulanic acid
(co-amoxiclav) | Clavulanate competitively and irreversibly
inhibits wide variety of beta-lactamases produced by
certain bacteria, making drug combination more potent. |
flucloxacillin | Flucloxacillin stable against
hydrolysis by variety of beta-lactamases, including
penicillinases, and cephalosporinases and extended
spectrum beta-lactamases |
Cefotaxime | Inhibition of cell wall synthesis via a penicillin-binding proteins. Displays resistance to penicillinases so useful to treat penicillin resistant |
nitrofurantoin | Inhibits bacterial acetyl-coenzyme A, interfering with
organism's carbohydrate metabolism. Can also disrupt
bacterial cell wall formation |
oxytetracycline | Reversibly binds to 30S ribosomal subunit and prevents
amino-acyl tRNA from binding to the A site of the
ribosome, inhibiting translation and thus cell growth |
vancomycin | glycopeptide antibiotic which acts by inhibiting cell wall
synthesis. |
ethambutol | Inhibits transfer of mycolic acids into cell wall of tubercle
bacillus |
isoniazid | Prodrug, which once activated, inhibits synthesis of
mycolic acids (essential component bacterial cell wall) |
pyrazinamide | Mechanism unclear. Metabolite (pyrazinoic acid) may
lower intrabacterial pH to level that could inactivate vital
target enzyme (e.g. fatty acid synthase. |
rifampicin | inhibits DNA-dependent RNA polymerase activity in
bacillus |
nystatin | Binds to sterols in cell membrane of susceptible
species, resulting in increased membrane permeability
and subsequent leakage of intracellular components. |
aciclovir | As triphosphate, competitively inhibits viral DNA
polymerase and competes with natural deoxyguanosine
triphosphate for incorporation into viral DNA, thus acting
as chain terminator |
ciclosporin | Binds to cyclophillin to form complex that inhibits
calcineurin, the enzyme that activates of transcription of |
ferrous salt | Essential element in synthesis of haemoglobin (as well
as myoglobin, cytochromes and other enzymes). |
folic acid | Critical cofactor in enzymatic reactions required for DNA
synthesis. Acts as carbon donor in the conversion of
deoxyuridine to deoxythymidine. |
hydroxocobalamin | Analogue of vitamin B12, which is converted to
cobalamin, cofactor for homocysteine-methionine
methyltransferase, which transfers methyl group from methyltetrahydrofolate to homocysteine to make methionine and thus ensure normal activation of folate. |
clopidogrel | Prodrug, active metabolite of which prevents binding of
adenosine diphosphate (ADP) to its platelet receptor,
impairing the ADP-mediated activation of the
glycoprotein GPIIb/IIIa complex |
dipyridamole | Inhibits both adenosine deaminase and
phosphodiesterase, preventing degradation of cAMP, an
inhibitor of platelet function. Elevation in cAMP blocks
release of arachidonic acid from membrane
phospholipids and reduces thromboxane A2 activity. |
Glycerl trinitrate | Converted to NO,activates guanylate cyclase.Stimulates guanosine 3', 5’-monophosphate (cGMP) which activates kinase phosphorylations in SM cells= dephosphorylation of SM myosin light chains. release of CA = relaxation of SM cells&vasodilation. |
isosorbide mononitrate | Converted to NO,activates guanylate cyclase.Stimulates guanosine 3', 5’-monophosphate (cGMP) which activates kinase phosphorylations in SM cells= dephosphorylation of SM myosin light chains. release of CA = relaxation of SM cells&vasodilation. |
nicorandil | Combines KATP channel activation with NO donor
activity, and is used in refractory angina |
adenosine | Slows conduction time through AVN, interrupting re-entry pathways through A-V node, and thus restoring normal sinus rhythm in patients with paroxysmal supraventricular tachycardia (PSVT), including PSVT associated with Wolff-Parkinson-White Syndrome |
amiodarone | Prolongs myocardial cell AP, (phase 3)duraion and refractory period and acts as a non-competitive a and B adrenergic inhibitor. |
losartan | Competitive antagonist at angiotensin II AT1-receptor on
vascular smooth muscle |
doxazosin | Inhibits postsynaptic alpha (1)-adrenoceptors on vascular smooth muscle. This inhibits vasoconstrictor effect of circulating and locally released catecholamines (epinephrine and norepinephrine), resulting in peripheral
vasodilatation |
bisoprolol | B blocker, acts as competitive antagonist of sympathomimetic NT such as catecholamines for binding at beta (1)-adrenergic R in the heart, but to a lesser extent at beta (2)R. Lipophilic exhibits no (ISA) or membrane stabilizing activity. |
dopamine | Produces +ve chronotropic and inotropic effects on the myocardium,=increased HR&conractility. exerting an agonist action on beta-adrenoceptors& indirectly by causing release of norepinephrine from storage sites in sympathetic nerve endings |
streptokinase | Cleaves Arg/Val bond in plasminogen to form proteolytic
enzyme plasmin. Plasmin in turn degrades fibrin matrix
of thrombus, thereby exerting thrombolytic action (also
rt-PA and tenecteplase) |
tropicamide | Inhibits sodium reabsorption in the distal convoluted
tubules and collecting ducts in the kidneys by binding to
the amiloride-sensitive sodium channels. This promotes
the loss of sodium and water from the body, but without
depleting potassium |
spironolactone | specific antagonist of aldosterone, acting through competitive binding of receptors at the
aldosterone-dependent sodium-potassium exchange
site in the DCT, thus causing
increased amounts of sodium and water to be excreted, while K is retained |
compound alginate preparations | Allginate + anatacid increases the viscosity of the stomach contents and can protect oeophageal mucosa from reflux. Some preparations form a viscous gel (raft) that floats on the surface of stomach contents, thereby reducing reflx |
omeprazole | Proton pump inhibitor that suppresses gastric acid
secretion by specific inhibition of the H+
/K+
-ATPase in
the gastric parietal cell, blocking the final step in HCL
production. (Lansoprazole is also widely used) |
metoclopramide | Dopamine antagonist which raises threshold of activity
in the chemoreceptor trigger zone and decreases input
from afferent visceral nerves. Also increases gastric
emptying rate (domperidone similar) |
ondansetron | Selective antagonist of serotonin (5-HT3) receptors
located on nerve terminals of vagus in periphery and
centrally in the chemoreceptor trigger zone of the area
postrema. |
prochlorperazine | Antagonist of dopamine in chemoreceptor trigger zone.
Also antagonist at cholinergic and alpha-adrenergic
receptors |
promethazine | Competes with free histamine for binding at H1-receptor sites in GIT, uterus, large blood vessels,& bronchial muscle. Relief of nausea appears related to central anticholinergic actions and may implicate activity on the medullary CTZ (cyclizine similar) |
mesalazine | An aminosalicylate metabolized in gut to 5- aminosalicylic acid an antioxidant traps free radicals (potentially damaging by-products of metabolism)may diminishes inflammation locally by blocking cyclooxygenase&inhibiting prostaglandin production colon. |
ispaghula husk | Bulk-forming laxative. Polysaccharide polymer not
broken down by the normal processes of digestion in
upper GI tract. Form bulky hydrated mass in gut lumen
promoting peristalsis and improving faecal consistency |
lactulose | Semi-synthetic disaccharide,not absorbed from GIT,increases water in LI, either drawing fluid from body into bowel or retaining fluid. Produces osmotic diarrhoea of low faecal pH,discourages proliferation of NH4-producing organisms. |
senna | Stimulant laxative which directly stimulates the
myenteric plexus, resulting in increased peristalsis and
thus defecation |
loperamide | Non-selective calcium channel blocker that also binds to
opioid mu-receptors in the myenteric plexus to reduce
peristalsis. |
latanoprost | Prostaglandin F2 alpha analogue and prostanoid
selective FP receptor agonist that is believed to reduce
intraocular pressure (IOP) by increasing outflow of
aqueous humor. |
ipratropium bromide | Anticholinergic, which blocks muscarinic cholinergic receptors, without specificity for subtypes, resulting in decrease in formation of (cGMP). This results in effect on intracellular calcium, and therefore in decreased contractility of smooth muscle |
ascorbic acid | Reducing agent required for collagen formation,
synthesis of the biogenic sympathetic amines,
norepinephrine and epinephrine, and synthesis of
carnitine. |
nicotinamide (B3) | Precursor to nicotinamide adenine dinucleotide (NAD)
and nicotinamide adenine dinucleotide phosphate
(NADP), vital cofactors for many essential enzymes |
pyridoxine (B6) | In the form of coenzyme pyridoxal 5'phosphate, wide range of metabolic reactions and synthesis of Nt |
thiamine (B1) | Co-enzyme in several vital metabolic processes,
including oxidative decarboxylation of pyruvate to acetyl
CoA via pyruvate dehydrogenase. |