M1: Ch3 Drug Absorption & Distribution Flashcards
(129 cards)
0
Q
Refers to Drug Fate
A
Metabolism & Excretion
1
Q
Refers to Drug Disposition
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Absorption & Distribution
2
Q
Delivery of drug to the tissue
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Distribution
3
Q
Passage of drug from its site of administration into the blood
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Absorption
4
Q
Most important transfer mechanism for foreign substance. Down a concentration gradient. Drug molecules pass from high to low concentration.
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Passive Diffusion
5
Q
Pass to different pores of membrane via fenestrations. Important for small molecules.
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Filtration
6
Q
Example of an organ that utilizes Filtration
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Kindney (Glomeruli)
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Q
Agains a concentration gradient. Energy-dependent, Selective carrier-mediated & Saturable. From Low to High concentration. Uphill and against a concentration gradient.
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Active transport
8
Q
Drugs that uses Active transport
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Levodopa, Iron, PTU & 5-FU “LIP 5”
9
Q
Drugs that uses Active transport: for thyroid problems
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PTU
10
Q
Drugs that uses Active transport: for parkinsonism
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Levodopa
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Q
Drugs that uses Active transport: for cancer
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5-FU
12
Q
Drugs that uses Active transport: for blood dyscrasia
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Iron
13
Q
Down a concentration gradient. Does not require energy. Selective carrier-mediated. Saturable. Never against a concentration gradient. High to Low concentration.
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Facilitated Diffusion
14
Q
Examples of drugs using Facilitated Diffusion
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Vit. B12/Cobalamin
15
Q
Complexes with intrinsic factor the goes to ileum them detected by the intestinal cells
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Vit. B12
16
Q
Microscopic invaginations capable of cell drinking. In-pouching of cell wall.
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Pinocytosis
17
Q
An example of drug that uses Pinocytosis
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Botulinum toxin
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Q
Important in cell absorption. Example is Albumin may not be able to pass thru smaller sized membranes.
A
Basement membrane
19
Q
Contains tight junctions with tightly packed endothelial junction. Only drugs that have high lipid-water partition coefficient can penetrate.
A
Blood Brain Barrier
20
Q
BBB uses what mechanism of drug transfer
A
Passive & Facilitated Diffusion
21
Q
Can increase the permeability of BBB
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Inflammation (bacterial meningitis & encephalitis)
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Q
Substances that are lipid soluble crosses the placenta with relative ease in accordance with their partition coefficient and degree of ionization
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Placental Barrier
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Found at the specialized sertoli-sertoli cell junction, prevents certain chemotherapeutic agents thus hinders treatment of neoplasm.
A
Blood-Testis Barrier
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Four Parameters that Influence the rate of diffusion of drugs
Thickness, Permeability Coefficient, Surface Area & Concentration Gradient "TPS C"
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Fick's Law of Diffusion: Increase Concentration Gradient = _________ Diffusion.
Decrease
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Fick's Law of Diffusion: Increase of Surface Area = ________ Diffusion.
Increase
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Fick's Law of Diffusion: Increase of Membrane Thickness = _________ Diffusion.
Decrease
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Ratio of concentration of a drug in two phases (oil & water) polar & nonpolar. Measure drug affinity to lipid and water.
Lipid-Water Partition Coefficient
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Formula for Lipid-Water Partition Coefficient
Kp = Coil / Cwater
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Increase in Kp means
Soluble in oil
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Decrease Kp means
Soluble in water
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The polarity of drug influences its
Solubility
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Increase polarity of drug = _____ water solubility. Thus Kp is ______.
Increased. Decreased.
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Decrease polarity of drug = _____ water solubility. Thus Kp is ______.
Decrease. Increase.
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More nonpolar means
More soluble to oil
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Less nonpolar means
Less soluble to oil
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Drug that is polar, ionized = ______ Kp (<1); soluble in ________.
Decreased. Water.
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Drug that is nonpolar, non-ionized = ______ Kp (>1); soluble in ________.
Decreased. Lipid.
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Ionization extent of Drug is based on
pH solution & pKa
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Formula for total drug concentration
pH - pKa = log R/RH (unprotonated/protonated)
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Fully ionized in a region of acidic environment. Goes into Intestine. _______ form will dominate.
Weak bases. Unionized.
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More lipid soluble substances & able to cross membranes (lipophilic)
Unionized form
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Base favors basic environment. Intestine is less acidic: ___________.
Unionized form
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Base favors basic environment. Stomach is acidic: ___________.
Ionized form
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Causes trapping
Ionized form
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Able to pass
Unionized form
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Weak Base in the Intestine is
Unionized
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Weak Base in the GIT is
Ionized
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Weak Acid in the GIT is
Unionized
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Weak Acid in the Intestine is
Ionized
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2 BE drugs necessarily need to have the same PE?
Yes
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Convenient (easy administration especially capsule and tablet) Requires no medical skills or conditions. Appropriate fro outpatient use and medicines OTC. Those having difficulty in swallowing tablets/capsule can use solution/suspension form.
Oral forms
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Drugs that can't be taken orally due to GI acidity: sensitive to action of proteases of the gastric enzymes.
Insulin
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Route of administration of Insulin
SubQ
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Drugs that can't be taken orally due to GI acidity: Antibiotics which are sensitive to gastric acids.
Methicillin & Penzylpenicillin
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Drugs that can't be taken orally due to GI acidity
Oxytocin, Penzylpenicillin, Insulin & Methicillin "OPiM"
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Oral administered drugs are usually absorbed via
Passive Diffusion
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Solid components separated from liquid. Needs to be shaked.
Suspension
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Fluid preparation
Solution
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Combination of oil & water
Emulsion
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Hard & Chewed in the mouth
Lozenges
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Drugs bypass distribution and undergo metabolism
Pre-systemic Metabolism
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PSM is plotted using
Area Concentration Curve (Drug Concentration over Time)
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An antifungal drug which is inactivated by PSM. Instead uses Isosorbate which is more stable. Also used for angina pectoris.
Glyceryl Nitrate
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An antipsychotic drug that undergoes pre systemic circulation. Huge discrepancy if the drug is given orally versus IM & IV.
Chlorpropazine
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Fractions of the drug which is available in the systemic circulation and obtained by comparing the Area under the curve of drugs with those that of an IV.
Bioavailability
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Formula for Bioavailability
BA = AUC oral/ AUC IV x 100
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Comparing the rate of absorption of two drugs. Rate and Bioavailability after administration are similar with the same route.
Bioequivalence
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Two drugs having the same active ingredient, concentration, form, amount, strength and concentration but doesn't mean they have the same bioavailability.
Pharmaceutic Equivalence
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Both drugs have the same effect
Therapeutic equivalence
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Renders the drug inactive
Presystemic circulation
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Bioequivalence should always be pharmaceutically equivalent but not all pharmaceutical equivalence is ________.
Buoequivalent
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Inactive drug that becomes active when metabolized.
Prodrug
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Prednesone is a corticosteroid and is inactive. Active form of which is
Prednisolone
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Located in the apical portion of intestinal cells. Principal action is once a molecule gets inside the cell, it will pump out the molecule. Efflux mechanism.
P-Glycoprotein
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GI motility: increase motility (diarrhea) leads to ________ transit time resulting to _______ absorption.
Decrease. Decrease.
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GI motility: decrease motility equals
Increase absorption
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GI motility: increase motility equals
Decrease absorption
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GI motility: Antimuscarinic drug which decreases GI motility
Loperamide
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Passage of blood from the aorta to the different tissues.
Splanchnic Blood Flow
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Decrease Splanchnic Blood Flow (fasting) = _______ rate of drug absorption.
Decrease
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Food & Drugs: increase absorption with intake of a fatty meal
Griseofulvin (antifungal)
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Food & Drugs: increases absorption of drug if taken together.
Grapefruit juice + Felodipine (antihypertensive)
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Food & Drugs: decrease absorption when taken with milk, calcium, FeSo4 and antacids like magnesium because they contain divalent ions.
Tetracycline (antibiotic)
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Other forms of Drug Administration
Sublingual, Intravenous/arterial, SubQ, IM, Rectal, Inhalation & Intradermal "SISIRIiN"
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Angle for IM
90°
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Example of IM drugs
Flu vaccine
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Angle for SubQ
45°
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Example of drugs administered SubQ
Insulin
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Angle for Intradermal
10-15°
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Example for drugs given ID
PPD, skin test
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Examples are Nifedipine & Captopril for gradual decrease of BP
Sublingual Administration
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A denitrate form. A sublingually taken drug.
Isodril
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Examples of drug rectally administered
Suppository (Paracetamol)
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For seizure
Diazepam
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Inhaled but has solid particles
Insufflation
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Drugs that are administered thru Inhalation
Salbutamol
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Drugs absorbed enter the general circulation directly if drug has high lipid-water coefficient. Drug absorption is limited. Extensive network of blood vessels facilitates rapid absorption.
Oral cavity & Sublingual Absorption
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Rich in blood supply and contact with epithelial lining is a potential site for drug absorption. Extent of absorption vary individually.
Absorption in the Stomach
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May affect the degree of ionization thus affecting absorption
Low pH
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Large surface area and high blood perfusion; greater capacity for absorption. Proximal jejunum. Utilizes facilitated, active, filtration and pinocytosis.
Absorption from the Small Intestine
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Smaller absorptive surface area; little absorption. Site of absorption especially for drugs not completely absorbed in the SI.
Absorption from the Large Intestine
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Factors Affecting Rate of GI Absorption
Gastric emptying time, Intestinal motility, Food & Formulation factors. "GIFF"
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Gastric Emptying Time: Increase in GET equals
Increase drug absorption
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Intestinal Motility: Absorption depends on _____ and change in ______.
Drug. Motility.
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Food: Most drug absorption is ______ or ______ in presence of food. Increase __________ increase rate of absorption.
Reduced or delayed. Splanchnic blood flow.
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Ability of drug forms and solubility in highly acidic gastric juice must be considered
Formulation factors
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Major site of administration agents for both local and systemic effects. Facilitated by large surface area of the pulmonary alveolar membrane. Rapid absorption & high lipid-water partition coefficient and smaller molecular radii of such agents.
Absorption of drug in the lungs
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Driving force (measure the capacity of blood to dissolve drug) Absorption of drug in the Lungs.
Blood-Air partition coefficient
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Determined by lipid-water partition coefficient
Absorption of drugs through Skin
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Absorption of drugs through Skin: barrier against rapid penetration of most drugs
Stratum corneum (epidermis)
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Absorption of drugs through Skin: well supplied with blood vessels permeable to both lipid and water soluble compounds.
Dermis
113
Most common means of parenteral administration. Increase realibilitu and precision in the drug blood level finally achieved, rapid absorption and onset effect. However, painful, local tissue necrosis and etc.
IM & SubQ
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Ensures immediate pharmacological response. Useful for compounds that are poorly or erratically absorbed. Possible overdose, embolism & infection.
IV
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Factors Influencing Drug Distribution: _________ permeability.
Capillary
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Factors Influencing Drug Distribution: ______________ ratio.
Blood flow tissue mass
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Factors Influencing Drug Distribution: Extent of ________ and specific organ _______.
Plasma protein. Binding.
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Factors Influencing Drug Distribution: Regional differences in _____.
pH
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Factors Influencing Drug Distribution: __________ available.
Transport mechanism
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Factors Influencing Drug Distribution: _________ characteristics of specific tissue membrane.
Permeability
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The volume of fluid required to dissolve the amount of drug in the body. Will move through systems until reach equilibrium.
Apparent Volume of Distribution (Vd)
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Protein Binding: Increase PB = _______ vd, because it is confined in only one area.
Decrease
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Protein Binding: Decrease PB= _______ free drug = ______ vd.
Increase. Increase.
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Dye to measure plasma volume. Binds to albumin. (heparin)
Evan's Blue
125
Water soluble polysaccharide. Does not enter cell. For ECF. (Pen G & Tubocurarine)
Inulin
126
To measure Total Body Water. Isotopic labeled water. (Ethanol,digoxin)
Deuterium Oxide (D2O)
127
Most are reversible due to hydrophobic characteristic
Protein binding
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Protein binding: the greater the binding, vd becomes ______, _______ available drugs to receptor.
Reduced. Lesser.
