D.5 Delivery of nitrates by buccal and transdermal route Flashcards
What are nitrates used to treat?
Symptoms of angina
What three ways can nitrates be used to treat angina ?
To relieve an attack that is occuring by using the medicine when the attack begins
To prevent attacks from occuring by using the medicine just before an attack is expected to occur
To reduce the number of attacks that occur by using the medicine regularly on a long-term basis
What are organic nitrates?
Potent vasodilators
How would you synthesis glyceryl trinitrate (GTN)?
Glycerol + HNO3 —-> GTN
Isosrobid + HNO3 —-> Isosorbid dinitrate
Why is there an explostion when high pressure is applied to glycerin trinitrate?
Massive increase of gas which leads to an explusion
True/false? Organic nitrates require enzymic processes to for NO?
True
What is activated when NO is released in smooth muscle ?
Guanylyl cyclase which increases cGMP levels
This causes the relaxation of smooth muscles
What are the effects of nitrovasodilators ?
- Direct relaxant effect on vascular smooth muscle and the dilation of coronary vessels which imporve the oxygen supply to the myocardium (heart).
- The dilation of peripheral veins, and in higher doses periheral arteries, reduces preload and after load, and thereby lowers myocardial oxygen condumption
- Inhibition of platlet aggregation
Why does admision of oral nitrates need to be administered at a high dose ?
First pass metabolism occurs in the liver which reduced the bioavailability of the nitrate
Why are short acting nitrates administered and what are there used?
Provide relief of an acute anginal attack
Used before physical activities to prevent anginal attacks
What are the benifits of sublingual tablets?
Absorption of drug through the oral mucous and direct access to the systemic circulation avoiding GIT
Fast action
What are long-acting nitrates used for ?
prophylaxis: to reduce the number of attacks that occur by using the medicine regularly in a long term basis
What are the disadvantages of long-acting nitrates and how can this be reduced
Nitrate toletrance- impares responsiveness
Have a break period (remove the patch for some time)
What is cross-tolerance in terms of nitrates
Stops other vasodilaters from working