Pharmacology Flashcards
Name the two ways in which drugs are classified
- The way in which they bring about their effect on the body
- The body system or infective agent they affect
Antimicrobial Agents
used to treat infections caused by
bacteria
fungi
virus
protozoa
Antibacterial drugs
may be bacteriocidal or bacteriostatic
will be narrow or broad spectrum
Bacteriocidal drugs
The drug kills the bacteria
Bacteriostatic
The drug stops the bacteria multiplying
means the immune system host must be able to defeat the organism. Not suitable if immunocompromised i.e. cats with FLV
Penicillin
e.g. amoxycilin
Broad spectrum
Bacteriocidal
Tetracyclines
e.g. Oxytetracycline
Broad spectrum
Bacteriostatic
Antiviral drugs
Not often used in small animal practice
feline herpes virus treated with aciclovir
(only viral treatment that’s not a vaccine)
Ivermectin Characteristics
acts by enhancing the actions of certain compounds in the body which inhibits nervous transmission.
It can produce an adverse reaction in collies
Praziquantel Characteristics
(In Milbemax)
effective against a wide range of tapeworms.
It increases the permeability of the cell membrane of the worm
resulting in a leaking of intracellular calcium & paralysis of the worm
Cardiac Drugs
Have a complex mode of action
multiple drugs are often prescribed at the same time (consider drug interactions)
Some cardiac drugs have serious side effects
Beta Blockers
anti-arrhythmic drugs
inhibit the stimulation of the beta receptors in the heart thereby reducing arrythmias e.g. propranolol
Digoxin
Similar effect to sympathomimetics, drug of choice for long term use.
has a very small theraputic index so must be used with care (toxic if dose slightly wrong)
Vasodilators
help to relax smooth muscle of the blood vessels which helps the blood to flow
reduces the amount of work the heart has to do to pump blood around the body
(arterial, veno and mixed dilators)
Mixed Vasodilator
acts on the arteries and veins
e.g. enalapril
Diuretics
increase the volume of urine produced and the amount of salt excreted
classified according to their mode of action
Loop Diuretics
Refers to action - loop of henle
causes diuresis by inhibiting the reabsorption of sodium from the loop of henle
Because sodium is in the urine, water is also retained
at the level of the distal convoluted tubule , potassium is exchanged for sodium. So sodium is reabsorbed back into the body while potassium is excreted.
Because osmotic pressure of the urine stays the same, the water stays in the urine and is excreted from the body along with the potassium.
Therefore, loop diuretics can result in hypokalaemia (K deficiency)
e.g. frusemide
Potassium Sparing Diuretics
Actively antagonises the production of aldosterone.
Aldosterone is the hormone responsible for the absorption of sodium from distal convoluted tubules and collecting ducts.
Because spironolactone stops aldosterone, sodium is not resorbed into the body, resulting in water not being reabsorbed either.
Potassium remains in the body because sodium is excreted, hence the name potassium sparing diuretics
What happens if ACE inhibitors and potassium sparing diuretics are used concurrently?
Hyperkalaemia may develop
