Dimenhydrinate

FORMULATIONS

METHOD OF PREPARATION

1 . Calculate the required quantity of each ingredient for the total amount to be prepared.

2. Accurately weigh and/or measure each ingredient.

3. Dissolve the dimenhydrinate and methylparaben in a mixture of the glycerin and ethanol.

4. Add the flavor and mix well.

5. Add the water and then sufficient syrup to volume and mix well.

6. Package and label.

PACKAGING

Package in tight, light-resistant containers.

LABELING

Protect from light. Keep out of reach of children.

STABILITY

A beyond-use date of up to 6 months can be used, dependent upon quality-control testing.1

USE

Dimenhydrinate is used in the prevention and treatment of nausea.

QUALITY CONTROL

Quality-control assessments can include weight/volume, pH, specific gravity, active drug assay, color, clarity, rheological properties, physical observation, and physical stability (discoloration, foreign materials, gas formation, and mold growth).2

DISCUSSION

Dimenhydrinate oral liquid was formerly available in three strengths: 12.5 mg/5 mL, 12.5 mg/4 mL, and 15.62 mg/5 mL; but all have been discontinued. The solid oral-dosage forms are still available.

Dimenhydrinate (C^sub 17^H^sub 21^ NO*C^sub 7^H^sub 7^C1N^sub 4^O^sub 2^, MW 469.96) occurs as a white, crystalline, odorless powder that is slightly soluble in water and freely soluble in alcohol.1 It is an ethanolaminederivative antihistamine that is used as an antiemetic. It is composed of 53% to 55.5% diphenhydrmaine and 44% to 45% of 8-chlorotheophylline. The injection has a pH in the range of 6.4 to 7.2. Dimenhydrinate is used in the prevention and treatment of nausea, vomiting and/or vertigo associated with motion sickness. It is most effective when administered prophylactically. It has also been used in the treatment of Meniere's disease and other vestibular disturbances.3

Glycerin (glycerol, 1,2,3-propane triol) occurs as a clear, colorless, odorless, viscous, hygroscopic liquid with a sweet taste about two thirds as sweet as that of sucrose. It has a specific gravity of about 1.25. It is miscible with water, methanol, and 95% ethanol; practically insoluble in oils and chloroform; and slightly soluble in acetone. It is hygroscopic and should be stored in airtight containers in a cool place. When mixed with water, ethanol, and propylene glycol, the mixtures are chemically stable.4

Ethanol 95% (C^sub 2^H^sub 5^OH, MW 46.07, ethyl alcohol, ethanol, grain alcohol) is a clear, colorless, mobile, and volatile liquid with a slight, characteristic odor and a burning taste. Alcohol USP refers to 95% ethanol, and dehydrated alcohol refers to 99.5% alcohol. Its specific gravity is between 0.812 and 0.816, and its boiling point is 78.15 deg C. It is miscible with chloroform, glycerin, and water. It should be stored in a cool place.5

Methylparaben (C^sub 8^H^sub 8^O^sub 3^, MW 152.15, methyl hydroxybenzoate, methyl parahydroxybenzoate) is available as colorless crystals or as a white, crystalline powder that is odorless, or almost odorless, and has a slight burning taste. Methylparaben is most effective in solutions between pH 4 to 8, and its efficacy decreases at higher pH levels. One gram is soluble in 400 mL of water, 3 mL of 95% ethanol, 60 mL glycerin, 200 mL peanut oil, and 5 mL propylene glycol; and it is practically insoluble in mineral oil.6

Purified water is water that is obtained by distillation, ion exchange, reverse osmosis or some other suitable process. It is miscible with most polar solvents and is chemically stable in all physical states (ice, liquid, and steam).7

Syrup (simple syrup) is a clear, sweet vehicle used as a sweetening agent and the base for many flavored and medicated syrups. It contains 85% w/v sucrose in water and has a specific gravity of not less than 1.30. It is generally self-preserving, as long as the sucrose concentration is maintained sufficiently high.

References

1. United States Pharmacopeial Convention, Inc. United States Pharmacopeia 26/National Formulary2l. Rockville, Maryland:US Pharmacopeial Convention, Inc.; 2003:628-630, 2197-2201, 2375, 2558,

2. Allen LV Jr. Standard operating procedure for performing physical quality assessment of oral and topical liquids. IJPC 1999;3:146-147.

3. McEvoy GK, ed. AHFS Drug Information-2002. Bethesda, Maryland: American Society of Health-System Pharmacists; 2002:2803-2805.

4. Price JC. Glycerin. In: Kibbe AH, ed. Handbook of Pharmaceutical Excipients. 3rd ed. Washington, DC:American Pharmaceutical Association; 2000:220-222.

5. Weller PJ. Alcohol. In: Kibbe AH, ed. Handbook of Pharmaceutical Excipients. 3rd ed. Washington, DC:American Pharmaceutical Association; 2000:7-9.

6. Reiger MM. Methylparaben. In: Kibbe AH, ed. Handbook of Pharmaceutical Excipients. 3rd ed. Washington, DC:American Pharmaceutical Association; 2000:340-344.

7. Ellison A, Nash RA, Wilkin MJ. Water. In: Kibbe AH, ed. Handbook of Pharmaceutical Excipients. 3rd ed. Washington, DC:American Pharmaceutical Association; 2000:580-584.

Copyright International Journal of Pharmaceutical Compounding May/Jun 2003
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