All LC pharma Flashcards
Example of Over the counter product
Lotrimin AF (Miconazole, spray)
Lotrimin AF (Clotrimazole, cream)
What is meant by over-the counter?
similar brand name different active ingrediant
why should we use generic and not brand name?
1) single drug multiple brand name (overdosing)
2) Over the counter product (same brand name different active ingrediant)
3) endanger international travelers
how do we excrete lipophilic drugs
they get metabolized in the liver and become hydrophilic via adding more structures to it
how does the pH of the medium affects a drug absorption? remember for a drug to become lipophilic it should be unionized
wek acidic drugs are absorbed better in the stomach as they are found in their unionized for there while weak base drug do the same in the intestine
what are the factors affecting drug absorption?
1) drug properties (lipid solubility, polarity, & molecular weight)
2) route of administration
3) blood flow to the absorption site
4) total SA available for absorbtion
5) Contact time at absorption surface
Expression of P-glycoproteins (P-glycoprotein is a transmembrane transporter protein throughout the body, including the liver, kidneys, placenta, intestines, and brain capillaries, and is involved in transportation of drugs from tissues to blood.
)
what are the types of enteric-coated tablets?
Acid resistant (allows absorption in intestine)
Alkaline sensitive (dissolves in upper intestine)
aspirin is coated to reduce the side effects
coatings either protects drug from stomach or stomach from drug (ulcers
sustained release tablets
Designed to slowly release drug from the formulation ->
rate of dissolution
rate of absorption
frequency of dosing
what is the effect of adrenaline on drug absorbance?
it decreases it as it causes vasoconstriction
which drugs are absorbed faster?
Inhalation→Sublingual→Rectal→intramuscular→subcutaneous→oral→transdermal
what does the area under the graph in the bioavailibity determination emphasizes?
extent of drug absorption
how can you calculate the bioavailibity of a drug from oral and iv graphs?
Area under the curve (oral/area under the curve IV) *100
what is meant by the therapeutic range?
the area between minimum effective concentration and minimum toxic concentration
what is meant by onset?
the time when the drug is given till it reaches the minimum effective concentration
what is meant by the duration of action?
it is the time from onset till it goes below the MEC again
what is the meaning of Bioequivalence,
we use it to describe two drugs, we say that drugs are bioequivalent if they have the same bioavailability and take similar timing to reach peak blood concentration.
what is the meaning of (blood brain barrier)
what is the meaning of volume of distribution,
Volume of distribution (Vd) = amount of drug in the body/ plasma concentration at time 0
OR
F (Bioavailability) * Dose / TC (target plasma concentration) = Vd
it tells us how extensively the drug is distributed to the rest of the body compared to the plasma
so for example you take a certain volume of water and a certain mass of drug, then divide the mass of the drug by the volume of liquid you will get C=mg/L
what are the factors that affect drug distribution?
1) blood flow (brain, liver & kidney has the highest BFlow)
2) capillary permeability
3) binding of the drug to plasma proteins and tissues (may cause drug accumulation in tissue)
4) lipophilicity of the drug
5) volume of distribution
what is meant by a loading dose?
the extra dosage is given initially to go beyond the MEC and below MTC then as it comes down again we give extra dosages at certain time intervals to always be above the MEC
Dose = Vd * TC / F
what is meant by pharmaceutical equivalents?
same active ingredient but one has a brand and the other is generic, they could be differences in
1: drug particle size
2: excipients
3: manufacturing equipment/process
4: site of manufacturing
they could have different bioavailability and be bioinequivelant
how to calculate a dosage?
you multiply the effective drug with its volume of distribution (Vd)
which drugs have the lowest Vd?
drugs restricted to the vascular compartments, as they are large, charged, and often protein bound like warfarin: 9.8L
which drugs have the highest Vd?
Drugs that accumulate in the tissues, as they are small, lipophilic, and unevenly distributed like chloroquine: 13000L