GBP7 Flashcards
(22 cards)
What does distribution of a drug mean`
movement of drug from circulating blood to sites of action, binding and elimination
What three thing does distribution depend on
relative arterial blood perfusion rate of different tissues
permeability characteristics of barriers
binding in blood or tissues
What tissues are highly perfused and will therefore be more likely to have distribution
blood cells, heart, lungs, kidneys, liver, glands, brain, uterus and placenta
What tissues have negligible perfusion
teeth, hair, bone, tendon, cartilage
What is the half life for thiopental
10 hours
What are the different phases of elimination of thiopental
alpha- concentration needed for surgical anaesthesia, high concentration in the brain rapidly decreases as it is redistributed, lasts 5-10 mins
beta- concentration slowly decreasing, has been redistributed and elimination is slow
Name three characteristics that make the blood brain barrier impermeable
few intracellular pores, lipid barrier, surrounded by glial cells
What effects the transfer of molecules across the BBB
lipid solubilty
binding
ionization
What is the significant difference between dompendone and metoclopramide
metoclopramide can penetrate the BBB and can cause drug induced parkonism
What is special about the placenta in terms of drug transfer
almost every dug crosses the placenta due to high blood flow
Name five drugs that cause problems with placental transfer
anti-epileptics anti-coagulants antibiotics anti-hypertensives anti-diabetics
What is use of anti-epileptics in pregnancy associated with
neural tube defects
facial defects
What drug do you swap warfarin to in pregnancy
Heparin because of large molecular weight and polarity doesnt cross the placenta
What anti-hypertensives are to be avoided in pregnancy
ACEinhibitors (stillbirth and renal agenesis)
Statins (abortion)
What antibiotic is to be avoided in pregnancy
Tetracycline, yellow/brown discolouration of teeth
What protein do acidic drugs bind to
Albumin
What protein do some basic drugs bind to
alpha1- acid Glycoprotein
What is the significant difference in action between bound and unbound drugs
only unbound drugs can - be transferred across membranes - be pharmacologically active - be metabolised or excreted
What may be the effect of liver dysfunction on a drugs action
Liver produces plasma proteins, less of these mean more of the drug will be in the unbound state and therefore may have an exaggerated effect
What drugs would you expect to have a Vd of 3L and why
largw bulky drugs eg Heparin, plasma expanders, monoclonal antibodies
What drugs would you expect to have a Vd of 12L and why
Some lipid soluble drugs tightly bound to plasma proteins = in interstitual fluid and plasma
eg. Warfarin, Ibruprofen
Polar water soluble drugs
eg. Penicillins, aminoglycosides, cephalosporins
What drugs would you expect to have a Vd of +40L and why
Digoxin, as it is avidly bound
