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PMP102 - Drugs and Medicines > Oral solution dosage forms > Flashcards

Oral solution dosage forms Flashcards

1
Q

What are some common forms of pharmaceutical solutions?

A

Injections, eye and ear drops, enemas, vaginal douches, topical
solutions, nebulisers.

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2
Q

What are two downsides to pharmaceutical solutions?

A
  • Rate of absorption can be limited by precipitation
  • Chemical stability is lowest in solutions
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3
Q

What is a pharmaceutical solution?

A

liquid preparations in which the
therapeutic agent and the various excipients are dissolved in
the chosen solvent system

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4
Q

What are some common liquid oral solution forms? + why so used?

A
  • Drugs are commonly given in solution
  • in cough/cold remedies
  • for the young and elderly (people with Parkinson’s)
  • Absorption from an oral solution is often rapid and complete, skip one step compared to tablets, greater bioavailability compared to other oral dosage forms
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5
Q

What are the advantages to pharmaceutical oral solutions?

A
  • Easily administered for individuals who have difficulty in
    swallowing, e.g. elderly patients, infants
  • The therapeutic agent is dissolved in the formulation and is
    therefore immediately available for absorption
  • Provided the drug does not precipitate within the gastrointestinal tract
  • Taste-masking of bitter therapeutic agents
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6
Q

What are the disadvantages to pharmaceutical oral solutions?

A
  • Unsuitable for therapeutic agents that are chemically unstable
    in the presence of water
  • The poor solubility of certain therapeutic agents may prohibit
    their formulation as pharmaceutical solutions
  • Expensive to ship and are bulky for the patient to carry
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7
Q

What are some examples of co-solvent excipients?

A

Ethanol, glycerol, propylene glycol

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8
Q

What are some examples of antioxidants excipients?

A

Sodium metabisulphite, ascorbic acid

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9
Q

What are some examples of antimicrobial preservatives excipients?

A

Benzalkonium chloride, parabens, potassium sorbate

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10
Q

What are some examples of pH adjusters excipients?

A

Citric acid, potassium phosphate

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11
Q

What are some examples of Isotonicity adjusters excipients?

A

Sodium chloride, glucose

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12
Q

What are some examples of viscosity enhancers excipients?

A

Hydroxymethylcellulose

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13
Q

What are some examples of chelating agents excipients?

A

EDTA

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14
Q

What are some examples of flavours excipients?

A

Taste masking

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15
Q

What are some examples of sweeteners excipients?

A

Sucrose, sorbitol, mannitol, aspartame, sucralose

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16
Q

What are some examples of colouring agents excipients?

A

Dyes

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17
Q

What type of water is used in pharm sols?

A

Tap drinking water not normally used for the manufacture of pharmaceutical solutions /extemporaneous compounding

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18
Q

If tap water is used/ water what type of processes must it go through to be used?

A
  • Purified by distillation, ion exchange, or reverse
    osmosis → non-parenteral solutions
  • Further purified to remove pyrogens (fever-
    producing compounds) → water for injections
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19
Q

What is a challenge in drug solubility?

A
  • Challenge: attainment of homogeneity in the formulation, due to limited aqueous solubility of the therapeutic agent
20
Q

What happens when drug solubility high?

A
  • Readily incorporated into the vehicle and formulated as an oral solution
21
Q

What happens when drug solubility is moderate?

A
  • Solubility enhanced using co-solvents or by related methods (changing pH, salt conversion)
22
Q

What happens when drug solubility is low?

A
  • Formulated as an alternative-dosage form, e.g. a suspension, emulsion biphasic
23
Q

What needs to happen in drug dissolution between therapeutic agent and water?

A
  • Removal of a molecule of the drug from the solid state
  • Formation of a cavity within the solvent
  • Accommodation of the drug molecule into the formed cavity.
24
Q

What factors affect the solubility of therapeutic agents?

A

*physicochemical properties
*big molecular weight (not likely to dissolve)
*big particle size (not likely to dissolve)
* solubility ∞1/melting point
*number of hydrogen bonds
*not many hydrophilic groups (not likely to dissolve)
* mostly crystalline (not likely to dissolve) / amorphous properties

25
Q

pH and pka in terms of solubility for acids and bases?

A

acids: pH > pKa = solubility increases
bases: pH < pKa = solubility increases

26
Q

What is the acceptable range for pH in oral solutions?

A

pH 5 - 8
cannot go below or above + can be adjusted using a buffer as long as its in the safe pH

27
Q

What is another way to increase pH?

A

converting weak acids into a salt

28
Q

Why can we not always change weak acids into salts?

A

*chemical stability, hygroscopicity,
manufacturability and crystallinity may preclude the choice of a
particular salt
*The sodium salt of aspirin, sodium acetylsalicylate, is much more
prone to hydrolysis (phenolic ester bond) than aspirin (acetylsalicylic
acid)

29
Q

What is a co-solvent?

A

liquid components (miscible in both phases) incorporated into a formulation to enhance the solubility of poorly soluble drugs

30
Q

What are commonly used co-solvents?

A
  • Glycerol
  • Ethanol
  • Propylene glycol
  • Poly(ethylene glycol)
31
Q

What are some properties of glycerol and propylene glycol?

A
  • Odourless, sweet, viscous
32
Q

What are some properties of ethanol?

A
  • Known pharmacological and
    toxicological effects have
    compromised use
33
Q

What are some properties of PEG?

A
  • Lower-molecular-weight grades
    (PEG 200, PEG 400) are
    preferred
34
Q

What is a cyclodextrin?

A

Enzymatically modified starches composed of
glucopyranose units which form a ring of either six (α-
cyclodextrin), seven (β-cyclodextrin) or eight (γ-cyclodextrin)
units

35
Q

Why are cyclodectrin used?

A
  • The ring of β-cyclodextrin is the correct size for most drug
    molecules, and normally one drug molecule will associate with
    one cyclodextrin molecule to form reversible complexes
36
Q

What are the purposes of excipients?

A
  • To facilitate the administration of the dosage form, e.g. pourability,
    palatability
  • To protect the formulation from issues regarding physical and chemical stability and to enhance the solubility of the therapeutic agent
    *physiologically inert
37
Q

What is the purpose of buffers?

A
  • To control the pH of the formulated product
  • To maintain the solubility of the therapeutic agent in the formulated
    product
  • To enhance the stability of products in which the chemical stability of
    the active agent is pH-dependent
38
Q

What are some examples of buffers?

A
  • Acetates (acetic acid and sodium acetate)
  • Citrates (citric acid and sodium citrate)
  • Phosphates (sodium phosphate and disodium phosphate)
39
Q

What is the purpose of sweetening agents?

A
  • To increase the palatability of the therapeutic agent
  • Main sweetening agents
  • Sucrose, liquid glucose, glycerol, sorbitol
  • Artificial sweetening agents is increasing in use
    *avoid in oral formulations for children and patients with diabetes mellitus
40
Q

What is the purpose of flavouring agents? +examples of flavours

A
  • To mask the taste of the drug substance
  • Salty: butterscotch, apricot, peach, vanilla, wintergreen mint
  • Bitter: cherry, mint, anise
  • Sweet: vanilla, fruit, berry
  • Sour: citrus, raspberry
  • Usually a combination to achieve the optimal
    taste-masking
41
Q

What else is in flavouring agents?

A

*methanol, chloroform to numb your taste buds to stop you from tasting the drugs

42
Q

What is the purpose of viscosity agents?

A
  • To ensure the accurate measurement of the volume to be dispensed
  • May increase palatability
43
Q

How are viscosity agents administered and controlled?

A
  • Administration performed using a
  • Syringe
  • Small-metered cup
  • Traditional 5-ml spoon
  • Increased (and controlled) by the addition of non-ionic or ionic hydrophilic
    polymers
44
Q

What is an antioxidant?

A

Molecules that exhibit higher oxidative potential
than the therapeutic agent, to inhibit free radical-induced drug
decomposition

45
Q

What is the purpose of antioxidants + examples?

A
  • To enhance the stability of therapeutic agents that are
    susceptible to chemical degradation by oxidation
  • aqueous
  • oil based
46
Q

What is the purpose of chelating agents?

A
  • To form complexes with heavy-metal ions involved in oxidative
    degradation of therapeutic agents
  • Ethylenediamine tetraacetic acid (EDTA)
  • Citric acid
47
Q

What is the purpose and properties of preservatives?

A
  • To control the microbial bioburden of the formulation
  • Ideal properties:
  • Broad antimicrobial spectrum (gram-positive, gram-negative bacteria and
    fungi)
  • Chemically and physically stable over the shelf-life of the product
  • Low toxicity

PMP102 - Drugs and Medicines (20 decks)

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