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31 Cards in this Set
- Front
- Back
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What is Pharmaceutics?
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The study concerned with the formulation, manufacture, stability, and effectiveness of dosage forms.
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What are the 2 components of a drug product?
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Drug Substance + Excipients
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Describe a typical tablet formulation.
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API - desired dose, Dilutants/fillers - sufficient, Binders - 3-5%, Disintegrants - 3-5%, Surfactant - .5-2%, lubricants/glidants - .25-1%
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What are the 2 principles of drug absorption?
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Passive Diffusion and Specialized Transport Mechanisms (active transport and facilitated diffusion)
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What is passive Diffusion?
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passage of molecules through a membrane that does not actively participate in the process, driven by concentration gradient across the membrane
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Describe the 2 specialized transport mechanisms.
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Active Transport: "carrier" with the the drug moving across membrane against concentration
gradient Facilitated Difussion: "carrier" but drug is not move against concentration gradient |
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What is Biopharmaceutics?
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The study of the relationship between the physical, chemical, and biologic aspects of drugs, dosage forms, and drug actions.
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What is pharmokinetics?
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study that elucidates time course of drug concentration in the blood and tissues.
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What is bioavailability?
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rate and extent to which an active drug is absorbed from drug product and becomes available at site of action
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What is the absolute bioavailability (F)?
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the fraction of the administered dose which reaches the systemic circulation relative to an IV Dose.
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What can the absolute bioavailability be used to determine?
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1)the amount of drug absorbed
2)rate of absorption 3)duration of drug's presence 4)relationship between drug blood levels and clinical efficacy and toxicity |
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What are the 3 parameters for Bioavailability assessment?
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1)Peak Height Conc. (Cmax)
2)Time of Peak Conc. (Tmax) 3)Area under blood concentration time curve (AUC) |
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What is Cmax and how is it expressed?
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Cmax occurs when the rates of absorption and elimination are equal. Expressed as concentration in a specific volume of blood.
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What happens to bioavailability when you increase the dose?
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the Cmax and AUC both increase
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What does the Tmax reflect?
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the rate of absorption and the time needed to reach minimum effective concentration (MEC) and maximum toxic concentration (MTC)
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What happens to bioavailability when the rate of absorption is decreased?
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the Cmax decreases and the Tmax occurs later
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What does the AUC represent?
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a measure of the total amount of drug absorbed following a single dose. equivalent doses of a drug produce the same AUC when fully absorbed, although Cmax and Tmax may vary
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How is bioavailability (F) calculated?
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Using the AUC (F = ((AUCpo)(DOSEiv))/((AUCiv)(DOSEpo))), using the amount excreted (F = ((AEpo)(DOSEiv))/((AEiv)(DOSEpo)))
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What are the consequences of a low bioavailability?
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1) if f<1, oral doses must be larger than IV doses.
2) as bioavailability decreases, variability from patient to patient increases |
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What factors influence bioavailability? How do we calculate total bioavailability?
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F = Fa x Fi x Fh
Fa - fraction not destroyed in gut or lost in feces Fi - fraction that escapes metabolism in intestine Fh - fraction that escapes metabolism on 1st pass of liver |
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How does lipophilicity affect oral bioavailability?
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lipophilic drugs more easily pass membranes
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How do weak acidic or weak basic drugs affect bioavailability?
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Weak bases favor absorption in the small intestine because they will be ionized in the low pH of stomach.
Weak acids will be non-ionized in the stomach, but still favor the small intestine because of the small surface area and low perfusion rate in the stomach |
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How does gastric emptying affect oral bioavailability?
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any delay in the drug reaching the small intestine will slow absorption.
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What is relative bioavailability and how is it calculated?
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It is the fraction of the administered dose which reaches the systemic circulation relative to another dosage form.
Frel = (AUCa x DOSEb)/(AUCb x DOSEa) |
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T/F, the same drug offered in different dosage forms always have the same bioavailability characteristics?
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False, they may have different bioavailability characteristics as well as different clinical effectiveness.
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5 standards that a generic drug must follow
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1)contain same active ingredient
2)be identical in strength, dosage form, and administration route 3)have same indications and precautions for use 4)be bioequivalent 5)meet same batch-to-batch requirements for identity, strength, purity, and quality |
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What are bioequivalent drugs?
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drugs that are similar in both rate and extent of bioavailability. have similar AUC and Cmax, but not necessarily same Tmax.
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What are pharmaceutical equivalents?
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1) same strength or amount of active ingredient
2) same dosage 3) same administration route |
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What are therapeutic equivalents?
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pharmaceutical equivalents that are expected to produce the same clinical effects and safety
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What contains all FDA assigned codes to approved drugs regarding therapeutical equivalence?
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"Approved Drug Products with Therapeutic Equivalence Evaluations" or "Orange Book"
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Describe the FDA drug ratings
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A - therapeutically equivalent
AA - no known issues related to bioequivalence AB - B - not therapeutically equivalent |
