Brand Name and Generic Aspirin ConcentrationA Study of the Effects of Steam and Humidity on Brand-Name and Generic Acetylsalicylic Acid

A Study by Paul Jones

Problem/ObservationOver-the-counter drugs and supplements claim that as long as certain conditions are met, it is safe to store them in your bathroom's medicine cabinet. Oftentimes brand-name and generic versions of the same drug have the same warnings about storage and storage conditions. But do they have the same rate of degeneration when stress is applied? Is the advertised dosage an accurate reflection of how much of something is truly in a pill? Is there an accurate method to analyze and quantify these questions when they're applied to the popular analgesic, acetylsalicylic acid, better known as aspirin. In conclusion, is it safe to store aspirin in a steamy-bathroom.

Aspirin

Formula - C9H8O4 Mol. Mass - 180.157 g/mol Density - 1.40 g/cm Melt. Point 135 C Boiling point 140 C Solubility in water - 3 mg/mL (20 C)

O

OH O O

Hypothesis I - MethodThe development of a method to quantify results of this experiment is as important as the results themselves. I hypothesize that I will be unable to execute a method accurate enough to explicitly quantify data, but I will be able to execute a method precise enough to be able to compare two data points objectively. This is important because it classifies this study as a comparative study.

Hypothesis II ConcentrationWith a precise enough method, I hypothesize that I could conclude relative differences in brand name and generic aspirins, both in untouched and degraded forms. Specifically, there will be no significant difference in pure-form brand name or generic aspirins, but there will be a small difference in concentration when they are exposed to steam, the literal steamy-bathroom. But the differences in aspirin concentration due to steam will be equivalent in both brand name and generic drugs. Considering that ASA degrades at 140 C, and steam is approximately 100 C, I hypothesize it is not a great risk to have aspirin in steamy bathroom conditions

Equipment/Supplies/Materials

Erlenmeyer flasks Cuvettes Graduated cylinder Pipets Volumetric flasks Spectrophotometer Brand-name (Bayer) and generic aspirin (Good Neighbor Pharmacy) Parafilm Sodium hydroxide (NaOH) Ferric (III) chloride (FeCl3)

Method OverviewThis method uses sodium hydroxide solution to hydrolyze ASA to produce salicylic acid. The salicylic acid then reacts with iron (III) to give a complex that absorbs light at 530nm. This absorption allows measurement using a spectrophotometer. As the study is comparative, standard (known) solutions of ASA are not required.

Method

(Excerpt from University of Pittsburgh at Bradford, "Spectrophotometric Analysis of Aspirin, Lab 019")

Place one aspirin tablet in a 125 mL Erlenmeyer flask. Add 10 mL of a sodium hydroxide solution to the flask, and heat until the contents begin to boil. Quantitatively transfer the solution to a 250 mL volumetric flask, and dilute with distilled water to the mark. Pipet a 2.5 mL sample of this aspirin tablet solution to a 50 mL volumetric flask. Dilute to the mark with a iron (III) solution. Place solution in a 125 mL Erlenmeyer flask.O O C CH 3 C O O- + [Fe(H2O)6 ] C O O+3

(s) + 3OH- (aq)

OC OO+

O (aq) + CH3C O - (aq) + 2H2O(l)

OH

O C O

Fe(H2O)4 O

+ H 2O + H 3O

+

Spectrophotometric Method

Turn on the spectrophotometer. Adjust the wavelength to 530nm. Insert the blank (0ppm cuvet of iron buffer) and set the blank to 0 absorbance. Obtain an absorbance reading for the aspirin sample.

Determination of Precision

Arithmetic mean of results Standard deviation of results Coefficient of variation = {[mean]/[standard deviation]} x 100%

Ideally, method should have coefficient of variation of within 20% in order to be accurate enough for comparison.

Results and PrecisionTest Brand-Name Generic Control Control 1 0.42 2 0.41 3 0.42 4 0.38 5 0.43 0.41 0.02 4.67% Brand-Name Generic Variable Variable 0.41 0.46 0.45 0.35 0.42 0.45 0.41 0.46 0.44 0.43 0.43 0.43 0.02 4.26% 0.05 10.78%

Mean Standard Deviation Coefficient of Variation

0.23 0.26 0.28 0.27 0.26 0.26 0.02

7.20%

Note All test results are in absorbance and not in transmittance.

Comparisons of Means0.45

0.4

0.35

0.3

0.25

0.2

0.15

0.1

0.05

0

Brand-Name Control

Generic Control

Brand-Name Variable

Generic Variable

Note The Y axis is in mean of absorbance units.

Analysis of ResultsThe results of my experiment clearly show a decrease of about 25% in the steamed generic ASA whereas the steamed brand-name ASA retained its structure. This would suggest that brand name ASA is more durable than generic. But the decreased concentration of the generic steamed pills shows that steam can definitely affect aspirin strength, and thus conclusively, one should not let one's aspirin come into contact with steam, humidity, or steamy-bathroom conditions.

Error Analysis DiscussionASA steam ASA + SA + A (steamed tablet) A + (SA + Fe) method(boiling NaOH)

530nmMy method of measuring aspirin breaks down the aspirin tablet into salicylic acid (SA) and makes it react with a iron (III) to create a complex that absorbs light at 530nm. But what if the steam the variable pills were exposed to broke down the aspirin into salicylic acid? If steam breaks aspirin down into salicylic acid, this method couldn't measure it.

Conclusions1. Aspirin concentration is affected by steam and humidity. 2. Based on advertised aspirin concentration and absorbency initial aspirin concentration is equivalent in both brand-name and generic ASA. 3. Brand-name aspirin has something that makes it more durable that generic aspirin. 4. My method can detect relative differences in aspirin concentration.

ConclusionSteam and humidity degrades aspirin, and it is possible for steam from one's shower to affect aspirin in one's medicine cabinet. My experiment was able to detect these changes in aspirin concentration, and precisely, too (within almost 10% coefficient of variation). Initial concentrations of brand name and generic aspirin were found to be equivalent, but not necessarily as advertised, for my experiment was relative, not quantitative, and I could not detect milligrams of aspirin. According to my results, once steam is applied, generic aspirin degrades while brand-name retains its structure.

Real World ApplicationKeep your aspirin sealed, in its container, away from steam. If you plan to consume the aspirin pretty immediately, generic aspirin will suffice. If you want your aspirin to last many days in your medicine cabinet, brandname is a much safer bet, as per potency.

Works Cited/Refrenced Articles

"Aspirin." Wikipedia, The Free Encyclopedia. 1 Jan 2010, 15:00 UTC. 5 Jan 2010 . University of Pittsburgh at Bradford, "Spectrophotometric Analysis of Aspirin, Lab 019". Science in Motion. S. Farrel, Dr.A. Aspirin Stability. Freshman Engineering Clinic I, 2003. Drugs.com, "Asprin". Cerner Multum. 1/4/10 .