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Dosage II > Liquid Dosage Forms > Flashcards

Liquid Dosage Forms Flashcards

1
Q

liquid dosage forms

A

-solution (homogenous molecular dispersion)
-emulsion (oil in water)
-suspension (solid in water or oil)

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2
Q

Solution dosage form examples

A

-injectables
-nasal, opthalmic, otic, irrigation solutions
-enemas
-douches
-gargles
-juices

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3
Q

Advantages of solution dosage forms

A

-homogenous (content uniformity)
-easy to manufacture
-good bioavailability

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4
Q

Components of solution dosage forms

A

-active ingredient
-solvent
-buffering agent
-preservative
-antioxidant, chelating agent
-flavor and sweetener

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5
Q

Solvent

A

-water, oils (for long-acting)
-co solvent (ethanol, glycerin)

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6
Q

Buffer principle

A

-solution of WEAK Acid and salt of CONjugate Base
-weak acid removes added base (OH-)

HA + OH- <–> H2O + A-

-salt removes added acid (H+)

A- + H3O+ <–>. HA + H2O

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7
Q

Henderson Hasselbach

A

pH = pKa + log[A-/HA]

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8
Q

Buffering capacity

A

-ability of a buffer to resist a change in pH due to added OH- or H+
-Van Slyke equation
-max when pH = pKa

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9
Q

van slyke equation

A

B = (acid or base added/pH)

B = 2.3 C (Ka[H3O+]/((Ka+[H3O+])^2)
-C= total buffer concentration = [HA] + [A-]
-max when pH = pKa

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10
Q

Common pharmaceutical buffers

A

-citric acid
-phosphoric acid
-also glycine and acetic acid

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11
Q

Citrate buffers

A

-

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12
Q

Phosphate buffers

A
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13
Q

Selection of pH

A

-use pH that provides maximum stability for drug
-minimize irritation by adjusting pH to be same as pH of body fluid 7.4

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14
Q

If you cannot match pH of body fluid,

A

-minimize buffering capacity
-minimize volume
-administer slowly

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15
Q

Antimicrobial preservatives purpose

A

-protect patient from pathogens
-maintain potency and stability of dosage forms

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16
Q

Antimicrobial preservatives mechanism of action

A

-absorb and disrupt bacterial membrane
-via lipid solubility or electrostatic attraction

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17
Q

bacterial membrane

A

-lipophillic
-negative surface charge

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18
Q

Adsorption due to lipid solubility (antimicrobial preservatives)

A

-alcohols
-acids
-esters

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19
Q

adsorption due to electrostatic attraction (antimicrobial preservatives)

A

quarternary ammonium compounds

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20
Q

bacterial content allowed in dosage forms

A

-ampules (sterile)
-multiple dose vials (sterile)
-ophthalmic solutions (sterile)
-oral liquids
-oral solids

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21
Q

Ampules

A

-must be sterile
-single dose
-no preservative needed

22
Q

Multiple dose vials

A

-must be sterile
-up to 10 doses
-NEED preservative to kill microorganisms

23
Q

Ophthalmic solutions

A

-must be sterile
-preservative if packaged as multiple dose use

24
Q

Oral liquids

A

-not sterile but no pathogens
-e. coli <100 per ml
-need preservative

25
Q

oral solids

A

-less likely to carry bacteria than liquids
-test raw materials
-clean manufacturing facility

26
Q

Ideal preservatives

A

-effective in low concentrations against a wide variety of organisms
-soluble in formulation
-non-toxic
-stable

27
Q

Pharmaceutical preservatives

A

-alcohols
-acids
-esters
-quarternary ammonium compounds

28
Q

Alcohols

A

-ethanol
-benzyl alcohol
-chlorobutanol

29
Q

ethanol

A

-requires more than 15%
-limited to oral
-may be lost due to volatility

30
Q

Benzyl alcohol

A

-local anesthetic action
-burning taste–not used orally
-water soluble
-stable over wide pH range
-used in parenterals

31
Q

Chlorobutanol

A

-campor-like odor and taste
-not used orally
-parenterals and ophtalmics
-volatile, lost through rubber and plastic

32
Q

Acids

A

-only active in unionized (lipid-soluble) form
-benzoic acid (oral)pka4.2
-sorbic acid (oral, good for mold and yeast) pka4.8

33
Q

Esters of P-hydroxybenzoic acid (parabens)

A

-widely used orally
-not ionize but hydrolyze rapidly at pH values above 7
-anesthetize tongue
-lipophilic ones good for mold and yeast
-less lipophilic ones good for bacteria
-low solubility is a problem
-cause skin sensitizatin when used dermatologically

34
Q

Quarternary ammonium compounds

A

-benzalkonium chlorise (Zephirin)
-Cetyltrimethylammonium chloride (Cepryn)
-ophthalmics
-water soluble
-fast killing
-incompatibility issues bc positive charge

35
Q

Factors affecting preservative action

A

-pH
-complex formation
-adsorption by solids
-chemical stability

36
Q

pH

A

-only unionized species of weak acids are effective as a preservative
-need to add more tatal weak acid when pH is above pKa in order to have effective concentration of unionized species

37
Q

complex formation

A

-only the uncomplexed (free) preservative is active

38
Q

Adsorption by solids

A

-only the unadsorbed preservative is active

39
Q

chemical stability

A

shelf-life

40
Q

Drug substances are less stable

A

-in aqueous media than solid dosage forms
-acid-base reactions, catalysis, oxidation, reduction may occur from container-product interactions

41
Q

Oxidation

A

-main degradation pathway of pharmaceuticals
-vitamins, fats
-auto-oxidation
-initiated by heat, light, peroxides, metals (cooper or ion)
-free radicals –> react with oxygen –> more free radicals

42
Q

auto-oxidation

A

-automatic reaction with oxygen without drastic external interference

43
Q

Antioxidants

A

-free-radical scavengers
-reducing agents
-chelating agents

44
Q

free-radical scavengers

A

-delay oxidation by rapidly reacting with free radicals
-gallic acid, BHT, BHA, Tocopherols, Vit E

45
Q

Reducing agents

A

-lower redox potentials than drug =. more readily oxidized
-sodium bisulfate: 2NaHSO3 + O2 –> 2NaHSO4
-ascorbic acid
-thiols

46
Q

chelating agents

A

-antioxidant synergists
-little antioxidant effect themselves
-remove trace metals
-citric acid, EDTA

47
Q

MAthcing

A

matching

48
Q

Ka=

A

-log(pKa)

49
Q

[H3O+] =

A

-log(pH)

50
Q
A

Dosage II (20 decks)

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