Enzyme inibitors Flashcards
what are some important drug targets for inhibiting enzymes?
AchE, ACE, COX, DPP IV, MAO, PDE, XO
AchE
acetylcholine esterase
COX
cycloxygenase
DPP IV
dipeptidyl peptidase
MAO
monoamine oxidase
XO
xanthine oxidase
what does ACE do?
convert angiotensin I to angiotensin II
what are some examples of ACE inhibitors?
captopril, enalapril (prodrug)
what do all ACE inhibitors end in?
-pril
what are ACE inhibitors used in clinically?
heart failure and hypertension
angiotensin II is a potent
vasoconstrictor
what does catopril work on?
the binding site one angiotensin I
what does angiotensin II do?
increase sympathetic activity
increase tubular Na+ and Cl- reabsorption
promote release of aldosterone from gland on kidney
arteriolar vasoconstriction
increase ADH secretion from pituitary gland (increasing collecting ducts H2O absorption)
what does the prodrug enalapril originate from?
enalaprilat
what are the clinical uses for acetylcholine esterase inhibitors?
Myasthenia gravis, glaucoma,
Alzheimer’s disease
what is an example of AchE inhibitor?
Physostigmine
what are the clinical uses for COX enzyme inhibitors?
Acute/chronic inflammation,
oedema, swelling & fever
which class of drug inhibits COX enzymes?
NSAIDs
what are prostaglandins synthesised from?
arachidonic acid
what do COX enzymes do in the synthesis of prostaglandins?
cut arachadonate into cycloendoperoxides (prostaglandins G and H)
what are coxs more selective for?
COX2 enzymes
example of NSAIDs
ibuprofen, aspin, diclofenac, naproxin
what does TXA2 do?
thromboxane - platelets - vasoconstrictor, Gaq signalling, Promotes clotting and vasodilation
what does PGF2a do?
vasoconstrictor, Gaq signalling
what does PGD2 do?
works in smooth muscle, vasodilator, Gas signalling
PGI2 - does?
vascular endothelium
- vasodilator, Gas signalling, increases pain sensitivity
why do NSAIDs lead to GI bleeding?
Prostaglandins that are made in the stomach – inhibit the production of acid, protect the mucosa, protects the GI tract
what are TX, PGI2, PGF2, PGD?
prostanoids
which enzyme synthesises leukotrienes from arachondonate?
5-lipoxygenase
what do leukotrienes do?
broncho-constricters - asthma
increase vascular complement
example of COX-2 selective inhibiter?
rofecoxib
which COX enzymes are expressed when?
COX1 – expressed at all times
COX2 - when there is pain and inflamation
what is the clinical use for Xanthine Oxidase?
gout - formation of painful crystals of uric acid
how does XO cause gout?
convert purines (aa’s) into uric acid - the painful crystals
what drug inhibits xanthine oxidase?
allopurinol (and oxipurinol)
how many distinct phosphodiesterase are there?
14
what does PDE do?
inactivates the second messenger cAMP - breaks it down
what are the 4 groups of PDEs?
non-specific, PDE III, PDE IV, PDE V
examples of non specific PDE inhibitors?
caffeine and theophylline (asthma)
examples of PDE III inhibitors?
arminone (CHF), cilostazol (intermittent claudication)
examples of PDE IV inhibitors?
Apremilast (psoriasis)
Roflumilast (COPD
examples of PDE V inhibitors?
sidenifil for erectile disfunction
what does sexual stimulation cause the smooth muscle cells in the walls of the arteries to do? result?
relax
- more blood flows into the sinusoids and so volume increase - erect penis
flaccid to erect penis
- sexual stimulation
- production of NO
- activation of guanlyl cyclase
- cGMP
- relaxation of smooth muscle of corpus cavenosum
- inc. blood flow
- errection
flaccid to erect penis
- sexual stimulation
- production of NO
- activation of guanlyl cyclase
- cGMP
- relaxation of smooth muscle of corpus cavenosum
- inc. blood flow
- errection
what are the clinical uses for monoamine oxidase inhibitors?
depression, anxiety, parkinson disease
what does monoamine oxidase do?
responsible for removing the neurotransmitters norepinephrine, serotonin and dopamine from the neurone/brain.
what do monoamine oxidases look like?
adreneline
what is the cheese reaction?
when people are taking monoamine oxidase inhibitors and they eat cheese and have an adverse reaction
where are the inactive metabolites formed by the monoamine oxidase get excreted?
in the urine
MAO non specific inhibitor?
phenalzine
MAOa inhibitor
moclobemide
MAOb inhibitor
selegiline
what dose dipeptidyl peptidase 4 do?
inactivates the incretin
what do incretin hormones do?
lower blood glucose by increasing insulin secretion, suppressing glucagon and slowing gastric emptying
what do DPP 4 inhibitors do?
prolong incretin activity and lower blood glucose levels
what are the clinical uses for DPP4 inhibitors?
diabetes and obesity
examples of incretin hormones?
GLP-1, GIT
examples of DPP4 inhibitors
gliptins (block incretin breakdown) - sitagliptin, ildagliptin
what does exenatide do?
GLP-1 mimetic - mimics the incretin that lower blood glucose