Pharmaceutical Shelf Life and Stability
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Questions and Answers

What does unimolecular mean in the context of molecularity?

  • Two molecules are required for the reaction.
  • A single molecule produces the product. (correct)
  • Multiple atoms interact to form a product.
  • A mixture of reactants produces multiple products.

    • Which best describes pseudofirst order kinetics?

  • All reactants are in equal concentrations.
  • The reaction rate is independent of the concentration of all reactants.
  • One reactant is in large excess while others are minimal. (correct)
  • Only first-order kinetics applies to drug degradation.

    • In bimolecular reactions, how many molecules come together to produce the product?

  • One molecule.
  • Two molecules. (correct)
  • Four or more molecules.
  • Three molecules.

    • Which of the following reactions could be described as pseudofirst order?

    <p>Drug + light → Products</p> Signup and view all the answers

    What characterizes an elementary reaction?

    <p>It defines the molecularity in terms of molecules reacting.</p> Signup and view all the answers

    What does shelf life indicate in the context of drug products?

    <p>The time a drug remains effective if stored properly.</p> Signup and view all the answers

    Which of the following is true about the expiration date of a drug product?

    <p>It designates when the drug is no longer within approved specifications.</p> Signup and view all the answers

    How is half-life defined in pharmacology?

    <p>The period required for a drug to decompose to one-half of its original concentration.</p> Signup and view all the answers

    What is the significance of the rate constant 'k' in relation to drug shelf life?

    <p>It is used by manufacturers to determine shelf life.</p> Signup and view all the answers

    Which statement correctly describes shelf life duration?

    <p>It is the time required for 10% of the drug material to disappear.</p> Signup and view all the answers

    What are the main strategies pharmacists can use to address chemical instability in drugs?

    <p>Adopting formulation changes, storage conditions, and packaging.</p> Signup and view all the answers

    How do drug formulations affect the stability of pharmaceuticals?

    <p>Different formulations can alter the degradation rate of drugs.</p> Signup and view all the answers

    Which of the following factors is NOT typically considered when determining a drug's shelf life?

    <p>Patient dosage and administration routes.</p> Signup and view all the answers

    What does a change in the specific rate constant, k, indicate?

    <p>It signifies a change at the molecular level due to altered conditions.</p> Signup and view all the answers

    Which of the following best describes molecularity in reactions?

    <p>The number of molecules that come together in an elementary reaction.</p> Signup and view all the answers

    Which type of reaction involves three molecules coming together?

    <p>Termolecular reaction</p> Signup and view all the answers

    What is a characteristic of complex reactions?

    <p>They proceed through multiple elementary steps.</p> Signup and view all the answers

    How are rate constants derived from complex reactions?

    <p>They are functions of the specific rate constants for the elementary steps.</p> Signup and view all the answers

    What is a common characteristic of reactions in aqueous solutions?

    <p>They often have contributions from solvent molecules.</p> Signup and view all the answers

    Which of the following statements is true regarding the variation of specific rate constants?

    <p>A variation in one specific rate constant usually affects others.</p> Signup and view all the answers

    Which reaction order is generally associated with the molecularity of a reaction?

    <p>The molecularity of an elementary reaction corresponds to its order.</p> Signup and view all the answers

    How does temperature specifically affect the rates of reactions?

    <p>It increases the frequency of successful collisions.</p> Signup and view all the answers

    What is the primary concept behind Collision Theory in relation to temperature?

    <p>More collisions per unit time result from higher temperatures.</p> Signup and view all the answers

    What is the frequency factor also known as?

    <p>Arrhenius factor</p> Signup and view all the answers

    What effect does an increase in temperature have on drug stability?

    <p>It reduces the overall stability of drugs.</p> Signup and view all the answers

    Why is the frequency factor important in evaluating reaction rates?

    <p>It indicates how frequently molecules collide with the correct orientation.</p> Signup and view all the answers

    What happens to reaction rates as temperature decreases?

    <p>Reaction rates decrease due to fewer collisions.</p> Signup and view all the answers

    In the context of temperature effects on shelf life, which factor plays a crucial role?

    <p>The rate of molecular collisions</p> Signup and view all the answers

    Which statement correctly summarizes the relationship between temperature and drug shelf life?

    <p>Increased temperature generally reduces shelf life.</p> Signup and view all the answers

    What is the primary purpose of packaging in pharmaceuticals?

    <p>To provide protection from environmental factors</p> Signup and view all the answers

    Which factor describes the ability of substances to move through packaging material?

    <p>Permeability</p> Signup and view all the answers

    What happens during leaching in the context of pharmaceutical packaging?

    <p>Materials transfer from the packaging into the drug solution</p> Signup and view all the answers

    Which type of glass is known to leach low levels of metal oxides into solutions?

    <p>Type I glass</p> Signup and view all the answers

    Why should caution be exercised when using other glass types for drug solutions with a pH greater than 7?

    <p>They may leach higher levels of harmful substances</p> Signup and view all the answers

    What are potential leachables from plastics used in packaging?

    <p>Additives and plasticizers</p> Signup and view all the answers

    Which substances can leach from rubber materials in stoppers and syringes?

    <p>2-mercaptobenzothiazole and nitrosamines</p> Signup and view all the answers

    Which environmental factor is critical for determining the shelf-life of drugs?

    <p>Humidity levels</p> Signup and view all the answers

    Study Notes

    Shelf Life

    • Shelf life is the time period during which a drug product is expected to remain within approved specifications for use, provided it is stored under the conditions defined on the container label.
    • Expiration date is the date placed on the container label of a drug product designating the date after which a batch of the product is not expected to remain with approved specifications, if stored under defined conditions, and after which it must not be used.
    • Half-Life: the period of time required for a drug to decompose to one-half of the original concentration
    • Manufacturers determine k, because of its relationship to shelf life
    • Drug in solution and suspensions decompose at different rates
    • Pharmacists must be able to recognize drugs with stability problems and have strategies to prevent those problems.
    • To overcome chemical instability, changes can be made to formulation, storage conditions, and packaging.
    • Drug stability is closely linked to chemical kinetics and rates of degradation.

    Rate Constants and Reaction Rates

    • Specific rate constant (k) is the constant in the rate law associated with an elementary reaction.
    • Any changes in reaction conditions such as temperature, solvent will lead to a different value for the specific rate constant.
    • Variations in the specific rate constant are of great physical significance because a change in this constant represents a change at the molecular level as a result of a variation in the reaction conditions.
    • Rate constants derived from reactions consisting of a number of steps of different molecularity are functions of the specific rate constants for the various steps.
    • Variations in an overall rate constant can be used to provide useful information about a reaction, but changes can affect multiple specific rate constants.

    Molecularity

    • A reaction whose overall order is measured can be considered to occur through several steps or elementary reactions.
    • Each of the elementary reactions has a stoichiometry giving the number of molecules taking part in that step.
    • The order of an elementary reaction gives the number of molecules coming together to react in the step; this is the molecularity of the elementary reaction.
    • Solution reactions, especially in aqueous solutions, generally involve contributions to their reaction mechanisms from solvent molecules, which require specialized techniques to quantify and to understand.
    • Reactions can be unimolecular, bimolecular, or termolecular (rare).
    • Complex reactions proceed through more than one step.

    Molecularity

    • Molecularity is the number of molecules, atoms, or ions coming together to react in an elementary reaction.
    • Unimolecular reactions: A single molecule produces the product.
    • Bimolecular reactions: Two molecules produce the product.

    Rates of Drug Degradation: Pseudofirst (Apparent) Order

    • Most drugs decompose by reacting with other species.
    • A simplified equation used to describe the reaction rate as pseudofirst order is used.
    • "Apparent" or "pseudo"-order describes a situation where all but one of the reactants is present in large excess, or do not affect the overall reaction and can be held constant.

    Learning Outcomes

    • Calculate shelf life with changes in temperature.
    • Describe environmental factors that affect shelf life.
    • List and evaluate the approaches used to prevent drug stability problems.

    Factors that Affect Shelf Life - Temperature

    • Rates of reaction are affected by temperature.
    • The reaction rate is expected to increase with increasing temperature based on collision theory.
    • Frequency factor (Arrhenius factor): a constant indicating how many collisions have the correct orientation to lead to products.

    Packaging

    • Packaging can be chosen to protect from oxygen, water vapor, and light.
    • Permeability: the ability of volatile substances to move through packaging material.
    • Leaching: loss of materials from the packaging into the drug solution.
    • Adsorption: Active or inactive components of drug solution adhere to the surface of packaging materials, which reduces the concentration in solution.

    Packaging Considerations

    • Type I glass leaches low levels of metal oxides into water and drug solutions.
    • Other glass types have higher levels of leaching and should be used with caution, especially for drug solutions with pH greater than 7.
    • Plastics have a number of additives that are potential leachables into drug solutions.
    • Rubber materials in stoppers and syringe plungers can leach metals, 2-mercaptobenzothiazole, and nitrosamines.

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    Drug Stability Part I - Biopharmaceutics - PDF

    Description

    This quiz covers essential concepts related to the shelf life and stability of pharmaceutical products. It includes definitions of shelf life, expiration dates, and half-life, as well as factors affecting drug stability. Insight into the role of pharmacists in managing drug stability and the chemical kinetics involved is also discussed.

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