Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
51 Cards in this Set
- Front
- Back
|
Define pharmacokinetics |
The study of drug movement in the body |
|
|
Rate of absoprtion determines _________, while the amount of absorption determines ________ |
how quickly the drug effect will occur, how intense the drug effect will be |
|
|
What are the 6 factors affecting rate of absorption? |
1. Rate of dissolution 2. Surface area 3. Blood Flow 4. Lipid Solubility 5. pH partitioning 6. Activity of Drug Transport Proteins |
|
|
Explain how rate of dissolution affects absorption |
Drugs must be dissolved in solution before they can become absorbed. Drugs that can disintegrate and dissolve (have a faster rate of dissolution) will have a greater rate of absorption, and thereby a faster onset of action |
|
|
What is the greatest determinant for rate of drug absorption? |
Surface Area |
|
|
What are the components of the stomach and intestine that add to their surface area? Which one has greater SA? |
Stomach has folds called rugae. Intestine has fingerlike projections called villi. Intestine has greater SA, so most drug absorption occurs there. |
|
|
Areas with _____ blood flow maintain a _______ _______ that drives absorption |
Areas with high blood flow maintain a concentration gradient which drives absorption |
|
|
What is a factor that can increase blood flow? |
Excercise. |
|
|
What are conditions that can decrease blood flow? |
Heart failure, hypotension, hypothermia, circulatory shock |
|
|
Explain how pH partitioning affects aborption |
If there is a pH difference between the region of absorption and the blood, such that the drug is ionized in the blood, becoming ion trapped, then rate of absorption will increase |
|
|
_____ transporters increase rate of absorption, whilst _______ transporters decrease ROA |
Uptake, Efflux |
|
|
Categorize the 8 routes of administration based on enteral, parenteral, and other |
|
|
|
What is the most common route of administration? |
Oral |
|
|
Name 2 advantages and disadvantages with oral administration |
Ad: safe, convenient, also economical Dis: Often incomplete absorption, also variable absorption between patients |
|
|
What is the surface area of the intestine? |
200 meters squared |
|
|
Marzopam, a weakly acidic drug, is orally ingested. Where is most of the drug likely to become absorbed? Why? |
Small intestine. Even though it is unionized in the stomach and ionized in the small intestine, the SA of the stomach is much smaller in comparison, and also the stomach has a layer of mucous, leading to greater absorption in the intestine |
|
|
What is the pharmaceutical phase? |
Occurs after a drug is orally ingested. The drug must undergo disintegration phase, into granules, then small particles. Then it must undergo dissolution phase and dissolve in the gastric solution. If it cannot do this, absorption is reduced. |
|
|
Define gastric emptying |
movement of stomach contents to the intestine |
|
|
Why is it that factors that increase gastric emptying increase rate of absorption? |
Because absorption is greater in the intestine than the stomach |
|
|
What are factors that increase gastric emptying? |
1. taking medications on an empty stomach 2. taking medications with cold water 3. lying down on the right side 4. High osmolality/tube feeding 5. Taking a prokinetic drug, which is a drug that increase gastrointestinal motility |
|
|
What are factors that decrease gastric emptying? |
1. Eating a high fat meal 2. Heavy Excercise 3. Lying down on the left side 4. Taking a drug that inhibits the vagus nerve, for example, anticholinergic drugs |
|
|
What is an enteric coating? |
A special coating that prevents drug disintegration and dissolution in the acidic environment of the stomach |
|
|
How are enteric coatings useful? |
They are useful for drugs that can be destroyed by the acidic environment of the stomach, and also drugs that can damage the stomach itself |
|
|
Define bioavailability |
the fraction of a dose of a drug that reaches the systemic circulation unchanged |
|
|
What are three factors that affect bioavailability? |
1. Drug formulation 2. Route of Administration 3. Degree of Metabolism |
|
|
What are the 9 oral drug formulations, in order of decreasing bioavailability |
ASS can get captured, contracting each tricep
Aqueous Solution syrup suspension
chewable tablet granules capsules
compressed tablet enteric coated tablets time release capsules |
|
|
Which drug formulations have no dissolution phase? |
Aqueous solution, syrup
|
|
|
Which drug formulations have slower disintegration phases? |
Enteric coated tablets, Time release capsules |
|
|
How are sublingually adminstered drugs absorbed? |
A drug is placed underneath the tongue. The drug passes through the oral mucosa, which then goes into the superior vena cava, directly to the heart. They still disintegrate and dissolve. |
|
|
T/F injected, sublingual and pulmonary adminstered drugs avoid first pass metabolism |
True |
|
|
What method of administration would you apply if you wanted a drug to act at the heart? |
Sublingual. Oral mucosa feeds into the superior vena cava which goes directly into the heart. |
|
|
What is special about transdermally administered drugs? |
They have a degree of both lipophilicity and hydrophilicity. Lipophilicity to penetrate the epidermis, and hydrophilicity to dissolve into the ECF |
|
|
What is one advantage and one disadvantage with transdermal preparations? How can the disadvantage be recitified? |
Advantage is they provide constant drug plamsa levels with minimal peaks and troughs. Disadvantage is this may induce tolerance, which is recitifed by enforcing drug free periods of 6-10 hours per day. |
|
|
What are the 5 factors that affect transdermal absorption, and in which way? |
1. Thickness of skin - Thicker the skin, slower the absorption 2. Hydration - Greater Skin Hydration, greater absorption 3. Hair follicles - More hair follicles, greater absorption (more areas for drugs to bypass) 4. Area of application - Greater area, greater absorption 5. Integrity of the skin barrier - psoriasis and burned skin can lead to greater transdermal drug absorption
|
|
|
Your patient is vomiting and you need to give him a drug, what route of administration do you choose? |
Rectal
|
|
|
T/F rectally administered drugs bypass the liver |
Both. 50% do. |
|
|
What are 2 disadvantages of rectal administration |
incomplete drug absorption, and suppositories may irritate the rectal mucosa |
|
|
Where are IV injections adminsitered on the body |
In a peripheral vein either on the back of the hand, or the median cubital vein on the elbow |
|
|
What are the 2 methods of IV administration? |
IV bolus - single dose over a short period of time IV drip- continuous dose administered over a long period of time. |
|
|
which method of administration often has drugs dissolved in a 'vehicle'? |
IV drip |
|
|
Name 4 advantages of IV |
1. 100% bioavailability 2. Easy to control dosage and duration of action 3. Allows administration of poorly soluble drugs 4. Allows injection of drugs that are irritants (drugs won't reach a high enough concentration to produce irritation) |
|
|
Name 4 disadvantages of IV |
1. Expenseive, invasive, inconvenience 2. Drug cannot be removed once injected 3. Risk of infection and fluid overload 4. Risk of injecting wrong formulation |
|
|
What is subcutaneous injection and what are its barriers to absorption? |
The drug is injected beneath the skin into the subcutaneous tissue. The only barrier to absorption is the capilliary wall |
|
|
What are 2 factors that affect rate of subcutaneous absorption? |
Rate of blood flow and water solubility of drug |
|
|
What is the barrier to absorption of IM injections? |
Capillary wall |
|
|
What are 2 factors that affect rate of IM absorption? |
Rate of blood flow and water solubility of drug |
|
|
What are 2 advantages of IM injections |
1. can be used to administer poorly soluble drugs 2. can be used to administer depot preparations (preparations in which drug is absorbed slowly over time) |
|
|
Rank these in order of decreasing blood flow vastus lateralis, gluteal, deltoid |
1. Deltoid 2. Vastus lateralis 3. gluteal |
|
|
Where are inhaled drugs absorbed? |
Pulmonary epithelium |
|
|
Why is pulmonary absorption so rapid? |
Large SA of lungs |
|
|
What route of administration is most common for general anaesthetics? |
Pulmonary |
