American Hospital Formulary Service (Ahfs)* Classification Number

28:08.92

Generic Name

USAN: acetaminophen

INN: paracetamol CAS#: 103-90-2

Source of Supply (Trade Name and Manufacturer)

TYLENOL® (acetaminophen) - McNeil Consumer Healthcare

Physical Properties Of The Chemical Entity¹

a. Structural Formula

b. Molecular Formula

C₈H₉NO₂

c. Molecular Weight

151.16

d. Macroscopic Appearance

Acetaminophen is a white, crystalline powder.

e. Solubility

water 1:70
boiling water 1:20
alcohol 1:10
chloroform 1:50
glycerin 1:40
ether slightly soluble

Chemical Properties

a. Structural Similarities/Differences of the Drug to Other Available Compounds or Groups of Compounds

Acetaminophen is a synthetic, nonopiate, centrally acting analgesic derived from p-aminophenol. The full chemical name is N-acetyl-p-aminophenol.

b. pKa

The pKa of acetaminophen is 9.51 at 25°C.

c. Stability of the Drug to Temperature, Light, and Moisture

Acetaminophen is stable to temperature, light, and moisture.

d. pH Range Over Which Drug is Stable in Solution

Acetaminophen is stable at a pH between 4 and 7 at 25°C.

e. pH of Commercially Available Liquid Products

Acetaminophen oral solution (ie, elixir, adult liquid) has a pH of 3.8 to 6.1 and the oral suspension (ie, infants' drops, children's suspension) has a pH of 5.4 to 6.9.

Extra Strength TYLENOL® acetaminophen Adult Liquid: 3058 ± 152 mmol/kg

Children's TYLENOL® acetaminophen Elixir: 6040 ± 25 mmol/kg

Because of the nature of suspension formulations, osmolarity of the TYLENOL® acetaminophen suspension products cannot be determined.

References

1. Remington's Pharmaceutical Sciences. 23rd ed. Easton, PA: Mack Publishing Company; 1995:1109-1110.

*Permission to use the Product Information Form for the American Hospital Formulary Service as modified by McNeil Consumer Healthcare has been granted by the American Society of Health-System Pharmacists, Inc., 7272 Wisconsin Avenue, Bethesda, MD 20814. The answers to all questions are prepared and furnished by the manufacturer. The answers were not supplied by the Society nor are they intended to imply the endorsement of the American Society of Health-System Pharmacists; neither does the Society affirm or deny the accuracy of the answers contained herein. Copyright© 1985, American Society of Health-System Pharmacists, Inc., all rights reserved.

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