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PMP-102 > Oral solution Dosage form I (Ingredients) > Flashcards

Oral solution Dosage form I (Ingredients) Flashcards

1
Q

Monophasic dosage form/oral

A
  • Ingredients
    -Methods
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2
Q

Everyday solutions

A
  • water
  • coffee
  • lucozade
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3
Q

Pharmaceutical solutions

A

Injections
Eye and ear drops
Enemas
Vaginal douches
Topical solutions
Nebulisers

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4
Q

Rate of absorption can be limited by…

A

precipitation

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5
Q

Chemical_____ is lowest in solutions

A

Stability

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6
Q

What are pharmaceutical solutions?

A

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

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7
Q

Liquid oral dosage forms (solution); examples

A

in cough/cold remedies
for the young/elderly (easier to swallow)

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8
Q

Liquid dosage forms have greater bioavailability compared to other oral dosage forms which means

A

absorption is rapid and complete

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9
Q

Advantages of liquid social dosage forms

A
  • 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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10
Q

Disadvantages of liquid forms

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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11
Q

example of co-solvents

A

alcohol, glycerol, propylene glycol help dissolve the drug

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12
Q

Colouring agents

A

dyes

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13
Q

Antioxidans

A

Sodium metabisulphate

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14
Q

pH adjusters

A

Citric acid

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15
Q

Why is tap water not used for the manufacture of pharmaceutical solutions?

A

Extemporaneous compounding

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16
Q

Non-parenteral solutions

A

Purified by distillation, ion exchange, or reverse osmosis

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17
Q

water for injections

A

Further purified to remove pyrogens (fever-producing compounds)

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18
Q

Drug solubility

A

Both the therapeutic agent and the excipients are required to be present in solution over the shelf-life of the formulated product
Needs to be homogeneous

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19
Q

What is a challenge of drug solubility?

A

attainment of homogeneity in the formulation, due to limited aqueous solubility of the therapeutic agent

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20
Q

Solubility at selected pH of formulation

A

High
> Readily incorporated into the vehicle and formulated as an oral solution

Moderate
> Solubility enhanced using co-solvents or by related methods (changing pH, salt conversion)

Low
> Formulated as an alternative-dosage form, e.g. a suspension

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21
Q

The dissolution of a therapeutic agent in water involves;

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.

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22
Q

Factors affecting the solubility of therapeutic agents; Physiochemical properties…

A

Molecular weight
Particle size
Solubility ∝ “1” /”melting point”
Number of hydrogen bonds
Hydrophilic groups (OH-, COO-, NH4+) > lipophilic groups (methyl, ethyl)
Crystalline/amorphous properties

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23
Q

Lower molecular weight, more or less soluble in water?

A

More soluble in water

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24
Q

The lower the boiling point…more or less soluble

A

More

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25
Factors affecting the solubility of therapeutic agents
Vast majority of drugs are either weak acids or bases and therefore solubility are pH-dependent The solubility of acids and bases increases as the degree of ionisation increases
26
For any acidic drugs (with one ionisable group)
pH > pKa, solubility increases
27
For any basic drugs (with one ionisable group)
pH < pKa, solubility increases
28
pKa equation
𝑝𝐾𝑎 = 𝑝𝐻+𝑙𝑜𝑔 [𝐶𝑖 ]/[𝐶𝑢 ]
29
Henderson-Hasselbalch equation
𝐷𝑖𝑠𝑠𝑜𝑐𝑖𝑎𝑡𝑖𝑜𝑛 𝑐𝑜𝑛𝑠𝑡𝑎𝑛𝑡, 𝐾_𝑎 = [𝐻^+ ][𝐴^−]/[𝐻𝐴] 𝑝𝐾_𝑎 = 𝑝𝐻+𝑙𝑜𝑔 [𝑎𝑐𝑖𝑑]/[𝑐𝑜𝑛𝑗𝑢𝑔𝑎𝑡𝑒 𝑏𝑎𝑠𝑒]
30
Weak acids
𝑝𝐻 − 𝑝𝐾𝑎 = log⁡([𝐴^−])/([𝐻𝐴]) Aspirin pKa = 3.0 pH stomach = 1.2 pH intestine = 6.8 pH blood = 7.4 pKa is larger than pH = negative value In stomach - more unionised
31
Weak base
𝑝𝐻−𝑝𝐾𝑎 = log⁡([𝐵:])/([𝐵𝐻^+]) Chlorpromazine pKa = 5.0 pH stomach = 1.2 pH intestine = 6.8 pH blood = 7.4 In stomach - more ionised
32
Optimisation of formulation pH
The solubility of an ionised therapeutic agent is a function of both the pKa of the compound and the pH of the formulation
33
Acceptable pH range of solutions for oral administration is large
5 - 8 pH units
34
Optimisation - achieve...
using a buffer that does not adversely affect the solubility of the therapeutic agent
35
Conversion of a weak acid to salt
1. The dissolution rate of a weakly acidic drug in gastric fluid (pH 1 - low) 2. ↑ pH in the diffusion layer, ↑ dissolution rate, ↑ saturation solubility (Cs), even though the bulk pH of gastric fluids remained the same 3. ↑ pH of the diffusion layer by changing weakly acidic drug from free acid to basic salt (the sodium or potassium form of the free acid) 4. The pH of the diffusion layer surrounding each particle of the salt form would be higher (e.g., 5 – 6) than the low bulk pH (1 – 3.5) of the gastric fluids because of the neutralising action of the strong anions (Na+ or K+) ions present in the diffusion layer
36
Conversion of a weak acid to salt?
Other factors - chemical stability, hygroscopicity, manufacturability and crystallinity may preclude the choice of a particular salt sodium salt of aspirin, sodium acetylsalicylate, is much more prone to hydrolysis (phenolic ester bond) than aspirin (acetylsalicylic acid)
37
Co-solvents - liquid components
Miscible in both phases
38
Prediction of the solubility of therapeutic agents in mixed solvent systems (the vehicle, water and the chosen co-solvent) is difficult IN PRACTICE:
In practice the pharmaceutical scientist should measure the solubility of the chosen therapeutic agent in a series of mixed solvents to determine the most suitable solvent system for the given purpose.
39
Micellar solubilisation
Incorporating drugs into or onto micelles Micellar solubilisation can also increase the solubility of drugs in the GI tract
40
Micellar solubilisation
Incorporating drugs into or onto micelles Micellar solubilisation can also increase the solubility of drugs in the GI tract
41
Cyclodextrin complexation
Cyclodextrins = Enzymatically modified starches composed of glucopyranose units which form a ring of either six (α-cyclodextrin), seven (β-cyclodextrin) or eight (γ-cyclodextrin) units 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
42
Excipients examples;
Buffers Sweetening agents, flavours, colourants Viscosity-enhancing agents Antioxidants, chelating agents Preservatives
43
Excipients purposes:
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
44
Buffer role;
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
45
pH paper
qualitative - showing colour not a pH value
46
Buffer examples;
Acetates (acetic acid and sodium acetate) Citrates (citric acid and sodium citrate) Phosphates (sodium phosphate and disodium phosphate)
47
Sweetening agents -
To increase the palatability of the therapeutic agent examples: Sucrose, liquid glucose, glycerol, sorbitol
48
Artificial sweetening agents
Aspartame Saccharin sodium used either as the sole sweetening agent or in combination with sugars or sorbitol to reduce the sugar concentration in the formulation
49
When to avoid using sweetening agents?
Avoid in oral formulations for children and patients with diabetes mellitus "SUGAR FREE/ FREE FROM SUGAR"
50
Flavours
mask the taste of the drug substance Red - strawberry Green - Mint Expect flavour
51
Viscosity-enhancing agents
To ensure the accurate measurement of the volume to be dispensed May increase palatability
52
Administration performed using a
Syringe Small-metered cup Traditional 5-ml spoon
53
Syrups, due to the inherent viscosity,
DO NOT require the specific addition of viscosity-enhancing agents
54
Increased (and controlled) by the addition of non-ionic or ionic hydrophilic polymers
Non-ionic (neutral) polymers Cellulose derivatives Methylcellulose Hydroxyethylcellulose Hydroxypropylcellulose Polyvinylpyrrolidone Ionic polymers Sodium carboxymethylcellulose (anionic) Sodium alginate (anionic)
55
Antioxidants
Molecules that exhibit higher oxidative potential than the therapeutic agent, to inhibit free radical-induced drug decomposition
56
Examples of antioxidants:
Aqueous solutions Sodium sulphite, sodium metabisulphite, sodium formaldehyde sulphoxylate and ascorbic acid Oil-based solutions Butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA) and propyl gallate
57
Chelating agents
form complexes with heavy-metal ions involved in oxidative degradation of therapeutic agents Ethylenediamine tetraacetic acid (EDTA) Citric acid
58
Preservatives
control the microbial bioburden of the formulation Ideal properties:
59
Examples of preservatives:
Benzoic acid and salts Sorbic acid and its salts Alkyl esters of parahydroxybenzoic acid
60
Revision; Drug solution
- Drug - Water, buffer, co-solvent - Sweeteners, flavours, colourants - Viscosity- modifying agents - Antioxidants, Chelating agents - Preservatives

PMP-102 (49 decks)

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