Dissolution Phenomenon
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Created by:
daisyflower on November 27, 2010
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Terms | Definitions |
|---|---|
 For drug to be absorbed into the systemic circulation and be distributed to site of action it ______ | has to be present in solution form at the site of absorption |
| Except for parenteral and oral administration of solution dosage forms, all other forms of drug need to ______ | dissolve in the medium around the site of administration/absorption to be absorbed, must be in solution form (dissolution form) |
| Dissolution is _____ | a process by which a solid solute with relatively low solubility enters into a solution in the presence of a solvent |
| Dissolution is used ____ | as a quality control tool to evaluate batch-batch uniformity of formulations (and drug availability for absorption) |
| Once tablet is introduced into a beaker or GI tract ____ | it undergoes a process of disintegration to produce granules (aggregates) |
| Granules ______ to form a fine powder, which undergoes dissolution | deaggregate |
| Dissolution of drug (drug entering solution) results from _____ | the fine powder form of the drug |
| Dissolved drug is _____ across the membrane and enters the ______ | absorbed, systemic circulation |
| No _____ of granules and ______ if capsule is available in powder form already | disintegration, deaggregation |
| If capsule has a pellet ____ | must follow disintegration, deaggregation, and dissolution (just like a tablet) to get to absorption |
| Tablet disintegrates into ____ and deaggregates to ____ which leads to dissolution _____ for absorption of drug into the _____ | granules, powder, drug in solution, systemic circulation |
| Concentration gradient (Cs-Cb) is ____ | the driving force of dissolution (difference in concentration) |
| Theory of diffusion (Diffusion-Layer Model) is ____ | rate of drug entering particle into bulk space (dissolution) |
| Noyes-Whitney is ____ | based on the diffusion layer model, describes the quantitative analysis of the amount of drug dissolved from a solid particle as a function of time |
| In Noyes-Whitney ____ | surface area and dissolution both increase (at a constant rate) |
| Dissolution Profile _____ | plateaus at non-sink condition (non-linear) |
| In Hixon-Crowell Cube Root, tablets, capsules, and suspensions particle size of the drug _____ | decreases as the drug dissolves, thus changing the effective surface area |
| Dissolution testing provides _____ | information regarding the total time for release of the drug |
| USP requires determination of time for _____ | 75% of the labeled amount of the drug to dissolve and be present in solution form |
| When a dosage form reaches its site of absorption _______ | the formulation must release the active ingredient to be absorbed into systemic circulation |
| Site of digestion is _____ and _______ | duodenum, jejunum |
| For oral dosage forms, the process begins with ____, _____, and _____ | disintegration, deaggregation, dissolution |
| After dissolution, the molecular form of the drug is ______ | absorbed across the membranes into the systemic circulation |
| For hydroPHOBIC drugs, ______ is the rate limiting step | dissolution |
| For hydroPHILIC drugs, ____ is the rate limiting step | absorption |
| Bioavailability is _____ | the fraction and rate of the dose administered that reaches the systemic circulation |
| Bioavailability of ______ drugs is dissolution rate limited, therefore, bioavailability of hydrophobic drugs is determined by the rate of which the drug dissolves in the aqueous medium | hydroPHOBIC |
| If bioavailability is low dissolution is ____ | low |
| Dissolution profiles of drugs can be manipulated through _____ or _____ changes | physicochemical, formulation |
| When manipulate dosage forms by making a capsule, suspension, or an emulsion, surface area _____ | increases |
| Rate and extent of drug dissolution are affected by ____, _____, and _____ | physiochemical properties of the drug, formulation factors of the dosage form, physiologic factors of the human being |
| When a person is fasting, pH _____ | is low (decreases) |
| In ionization state, salt form of weak electrolytes is _______ | more water soluble |
| In ionization state, dissolution is _____ | faster with salt forms |
| In ionization state, benzathin salt has _____ | lower solubility |
| In Noyes-Whitney Equation, rate of dissolution is _____ | directly proportional to surface area of the drug particles |
| Decreasing the particle size by micronization results in _____ | increase in surface area |
| For poorly soluble drugs, decreasing particle size can _____ | improve dissolution |
| When the dissolution medium has poor wetting properties, micronization sometimes results in _____ | poor dissolution rates due to agglomeration (clumping together) |
| Inclusion of surface active agents in the dissolution medium ____ | increases the rate of dissolution by wetting the particles |
| Wetting agents _____ contact angle of drug particles | decrease |
| Surface active agents inclusions ____ rate of dissolution by wetting the particles | increase |
| Amorphous forms are _____ than crystalline forms | more soluble |
| Amorphous state ______ dissolution of drug | increases |
| Crystalline forms require ______ to break crystal habit and allow formation of homogenous system | more energy |
| Lyophilized (freeze dried) products tend to be amorphous and dissolve faster so _____ | dissolution rate is improved |
| Polymeric materials (PEG, PVP) affect the rate of _____ | dissolution of hydrophobic drugs |
| Lubricating agents ____ the rate of dissolution by forming a hydrophobic layer on the particles | decrease |
| Enteric coated formulations are designed not to _____ | disintegrate and release their contents in the gastric fluid |
| Enteric coated drug, such as aspirin, should not disintegrate in stomach, it should only dissolve ___ | in the intestine (higher pH) |
| Disintegration, dissolution, and absorption occur _____ | in the intestine |
| In suspensions, _______ is the rate limiting step | dissolution |
| In suspension, there is an equilibrium between _____ and _____ | insoluble solid drug, saturated solution of the drug |
| _____ and ____ in a suspension cause dissolution rate to decrease | Settling, Aggregation |
| Drug dissolution from an emulsion results _____ from the oil phase into the aqueous phase and subsequently into the dissolution medium | from partitioning of the drug |
| Viscosity of the emulsion and suspension _______ the diffusion coefficient D, which _____ the rate of dissolution | decrease, decreases |
| Presence of food in the stomach ______ viscosity, which _____ the rate of dissolution, and _____ diffusion coefficient | increases, decreases, decreases |
| pH ____ when food is in stomach | increases |
| Intestinal pH is _____ | basic |
| Stomach pH is ______ | acidic |
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