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829 Dosage > Liquid Dosage Forms > Flashcards

Liquid Dosage Forms Flashcards

1
Q

Definition

Solution

A

Homogeneous molecular dispersion

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2
Q

Definition

Emulsion

A

oil in water/water in oil

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3
Q

Definition

Suspension

A

solid in water or oil

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4
Q

Advantages of Solution dosage forms

A
  • homogeneous - no problems of content uniformity
  • easy to manufacture
  • good bioavailability
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5
Q

Components of Solution

A
  • active ingredient (drug)
  • solvent
  • buffering agent
  • preservative
  • antioxidant, chelating agent
  • flavor and sweetener
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6
Q

Solvents used for long-acting parenterals

A

water, vegetable oils

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7
Q

Co-solvet examples

A
  • ethanol
  • glycerin
  • propylene glycol
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8
Q

Flavor and sweetener examples

A

sucrose and soritol

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9
Q

Buffer principle

A

a solution of a weak base and a salt of its conjugate base

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10
Q

Buffer equation for a weak acid removing added base (OH-):

A

HA + OH- ⇿ H2O + A-

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11
Q

Buffer equation for salt removing added acid (H+)

A

A- + H3O+ ⇿ HA + H2O

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12
Q

Handersen-Hasselbalch equation

A
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13
Q

Definition

Buffer capacity

A

Ability of a buffer to resist a change in pH due to added OH- or H+. Amount of strong acid or base needed to change pH by one unit.

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14
Q

Buffer capacity equation: 1

A
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15
Q

Buffer capacity equation: 2
(Van Slyke)

A

C = total buffer [ ] = [HA] + [A-]

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16
Q

T or F: Buffer is at max capacity where pH=pKa

A

True

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17
Q

Common pharmaceutical buffers

A
  • acetic acid
  • citric acid
  • glycine
  • phosphoric acid
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18
Q

what is this structure?

A

acetic acid

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19
Q

what is this structure?

A

citric acid

monobasic, dibasic, and tribasic

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20
Q

what is this structure?

A

glycine

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21
Q

what is this structure?

A

phosphoric acid

monobasic, dibasic, and tribasic

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22
Q

We want to select a pH that provides ___ ___ for the drug. If possible, we want the pH to match the pH of the ___.

A

maximum stability, body

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23
Q

When pH is selected we want to:
* ___ the buffering capacity
* ___ volume
* administer ___

A

minimize, minimize, slowly

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24
Q

Buffer Preparation - Exercise 1

A buffer contains 0.1 M sodium formate and 0.1 M formic acid. 0.03 M of sodium hydroxide was added. The Ka of formic acid is 1.77 x 10 -4
(pKa = -log(Ka) = 3.75).
1. What is the initial pH of the buffer?
2. What is the buffer capacity?
3. What is the pH after the addition of sodium hydroxide?

A
  • 3.75
  • 0.115 M
  • 4.02
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25
Q

Buffer Preparation – Exercise 2

Design a buffer for a penicillin solution that is most stable at pH 6.5. A buffer capacity of 0.15M is required.

A
  • HA (dibasic citrate) 0.117M
  • A- (tribasic citrate) 0.147M
26
Q

Antimicrobial Preservatives Mechanism of Action

A

Preservatives adsorb into the bacterial membrane and disrupt it. The membrane is lipophilic and has a net negative surface charge.

27
Q

Antimicrobial preservatives - 2 methods of adsorption

A

lipid solubility
* alcohols, acids, esters

Electrostatic attraction
* quaternary ammonium compounds

28
Q

Bacterial content allowed in various dosage forms

Ampules

A

must be sterile, single dose no preservative needed

29
Q

Bacterial content allowed in various dosage forms

Multiple dose vials

A

must be sterile, may contain up to 10 doses, need a preservative to kill microorganisms introduced during use

30
Q

Bacterial content allowed in various dosage forms

ophthalmic solutions

A

must be sterile, must contain a preservative if packaged in multiple dose container

31
Q

Bacterial content allowed in various dosage forms

oral liquids

A

need not to be sterile but should not contain pathogens. FDA limits the number of organisms to be less than 100/mL. Need preservative for multiple dose packages.

32
Q

Bacterial content allowed in various dosage forms

oral solids

A

less likely to carry bacteria than liquid forms. Pathogen contamination is still a concern. Test raw materials and be sure that the manufacturing facility is clean.

33
Q

Characteristics of ideal preservatives

A
  • effective in low [ ] against a wide variety of organisms
  • soluble in formulation
  • non toxic
  • stable
34
Q

Pharmaceutical preservatives

Alcohols
* ethanol: requires more than ___%, limited to oral products, may be lost due to ___
* ___: anesthetic action, burning taste (not used ___). Water ___, stable over wide pH range. Used for parenterals
* ___: campor-like odor and taste (not used orally). Used in ___ and ___. ___, lost through rubber stoppers and plastic containers.

A
  • 15%, volatility
  • benzyl, orally, soluble
  • chlorobutanol, parenterals, ophthalmics, volatile
35
Q

Pharmaceutical preservatives

Acids
* benzoic acid (pKa = ___): used in ___ products
* sorbic acid (pKa = ___): used in ___ products, excellent for ___ and ___

A
  • pKa = 4.2, oral
  • pKa = 4.8, oral, molds and yeast

only active in unionized (lipid-soluble) form

36
Q

T or F: acid preservatives are only active in unionized (lipid soluble) form.

A

True

37
Q

Pharmaceutical preservatives

Esters of p-hydroxybenzoic acid (Parabens)
* Used ___. Not ___ but ___ rapidly at pH values above ___.
* Anesthetize ___
* Most lipophilic ones (___ paraben and ___ paraben) are best against ___ and ___.
* Less lipophilic ones (___ paraben and ___ paraben) are best against ___.
* low ___ is a problem
* cause skin ___ when used in dermatological products

A
  • orally, ionized, hydrolyzed, 7
  • tongue
  • Propyl, butyl, mold, yeast
  • methyl, ethyl, bacteria
  • solubility
  • sensitization
38
Q

Pharmaceutical preservatives

Quaternary ammonium compounds
* Benzalkonium chloride (___)
* Cetyltrimethylammonium ___ (Cepryn)
* Widely used in ___. Very water ___ and ___ killing.
* Incompatibility issues due to ___ charge
* Interacts with negatively charged membrane

A
  • Zephirin
  • Chloride
  • ophthalmics, soluble, fast
  • positive
39
Q

What is this molecule an example of?

A

Esters of p-hydroxybenzoic acid (Parabens)

preservative

40
Q

What is this molecule and what is it an example of?

A

Benzalkonium chloride (Zephirin), Quaternary ammonium compounds

preservative

41
Q

What is this molecule and what is it an example of?

A

Cetyltrimethylammonium (Cepryn)

preservative

42
Q

Factors affecting preservative action

  • pH - only the ___ species of ___ acids are effective as a preservative. Need to add more total __ acid when pH is ___ pKa in order to have effective [ ] of unionized species.
  • complex formation - only the ___ preservative is active.
  • adsorption by solids - only the ___ preservative is active.
  • chemical stability - consider the ___.
A
  • unionized, weak, weak, above
  • free (uncomplexed)
  • unadsorbed
  • shelf-life
43
Q

Antioxidants

  • drug substances are __ stable in aq media than in solid dosage forms.
  • acid-base reactions, catalysis, oxidation, or reduction may occur from ingredient-ingredient interactions or ___-product interactions
A
  • less
  • container
44
Q

Antioxidants

Oxidation
* main ___ pathway of pharmaceuticals (vitamin, essential oils, fats, and oils)
* ___- automatic reaction with oxygen without drastic external interference
* initiated by ___, light, ___, metals (Cu and __)

A
  • degradation
  • auto-oxidation
  • heat, peroxide, Fe
45
Q

Antioxidants

Free-radical scavengers
* slow/delay oxidation by rapidly reacting with free radicals
* propyl, _, dodecyl esters of acid
* butylated hydroxyanisole (…); butylated hydroxytoluene (…)
* tocopherols; vitamin __

A
  • octyl, gallic
  • BHA, BHT
  • E
46
Q

Antioxidants

Reducing agents
* have __ redox potentials than drug; more readily ___
* sodium ___: 2NaHSO3 + O2 → 2NaHSO4
* ascorbic acid
* thiols

A
  • lower, oxidized
  • bisulfite
47
Q

Antioxidants

Chelating agents
* antioxidant ___
* little antioxidant effect themselves
* remove trace metals
* examples: ___ acid and ___

A
  • synergists
  • citric, EDTA
48
Q

Sodium bisulfite is a…

A

antioxidant acting by preferntial oxidation

49
Q

EDTA is a…

A

Chelating agent and antioxidant

50
Q

butylated hydroxytoluene (BHT) is a …

A

free radical stabilizer

51
Q

sorbitol is a…

A

sweetener

52
Q

glycerin is a…

A

co-solvent

53
Q

methylparaben is a…

A

preservative acting by lipophilic absorption

54
Q

benzalkonium chloride is a…

A

preservative acting by electrostatic adsorption

55
Q

ascorbic acid is a…

A

antioxidant and buffering agent

weak acid

56
Q

benzoic acid is a…

A

preservative (when unionized/protonated)

57
Q

chlorpromazine is an…

A

active ingredient

58
Q

citric acid is a…

A

chelating agent, buffering agent, and antioxidant

59
Q

propylene glycol is a…

A

co-solvent

60
Q

sodium dihydrogen citrate is a…

A

chelating agent, buffering agent, and antioxidant

61
Q

sucrose is a…

A

sweetener

62
Q

water is a..

A

solvent

829 Dosage (4 decks)

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