Vioxx Delivery Methods
Vioxx was available in both oral suspension and tablet formats. The oral suspension was off-white/yellow with strawberry flavoring. Vioxx tablets came in 12.5 mg, 25 mg, or 50 mg sizes, and could be taken with or without food.
Description of Vioxx Tablets
- 12.5 mg: round, off-white, engraved with MRK 74 on one side, VIOXX on the other.
- 25 mg: round, yellow, engraved with MRK 110 on one side, VIOXX on the other.
- 50 mg: round, orange, engraved with MRK 114 on one side, VIOXX on the other.
Commonly Prescribed Vioxx Dosages
For arthritis, a chronic condition, Vioxx had a recommended daily dose of no more than 25 mg. In some cases, dosages were adjusted for a particular patient’s needs, but Vioxx came with a general dosage guide as follows:
- Rheumatoid Arthritis: 25 mg once daily (same for treatment of Juvenile Rheumatoid Arthritis in patients aged 2 and up).
- Osteoarthritis: 12.5 or 25 mg once daily.
- Acute pain or dysmenorrhea: 50 mg once daily, for up to 5 days.
- Migraine Headaches: 25 or 50 mg once daily, up to 5 days per month.
Factors Affecting Vioxx Dosages
The patient’s body mass, size, weight, age, and diet may have a bearing on a doctor’s dosage adjustment of any medication. Merck (manufacturer of Vioxx) recommended that Vioxx be taken in the lowest possible effective dosages, particularly when used for long-term treatment. In other words, the chronicity and severity of the condition also had a bearing on what dosage of Vioxx patients were prescribed.
Vioxx Absorption Rates
The body’s absorption of a drug is represented graphically by a roughly bell-shaped curve, which shows the concentration of a drug in the bloodstream in relation to time, as shown below:
The drug’s concentration gradually increases as the body absorbs it; then the concentration peaks, and then gradually declines as the medication wears off. The term used to denote the total amount of a medication absorbed by an individual is the AUC, or Area Under the Curve.
Variations in AUC are observed when individual patients show different levels of the drug in their bloodstreams after the same amount of time has elapsed. An increased AUC means that a patient, in total, absorbs a higher than average amount of a drug. In this case, dosage may be lowered to compensate. Conversely, if a patient shows a decreased AUC, dosage may be raised.
The following AUC variations were observed in Vioxx clinical trials:
- 34% increase in AUC in elderly patients compared with young patients.
- 10-15% increase in AUC in people of African-American or Hispanic descent.
- Up to 30% decrease in AUC in patients with certain types of Hepatitis.
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