Ketoprofen - How It Works

CLINICAL PHARMACOLOGY Ketoprofen is a nonsteroidal anti-inflammatory drug with analgesic and antipyretic properties.

The anti-inflammatory, analgesic, and antipyretic properties of ketoprofen have been demonstrated in classical animal and in vitro test systems.

In anti-inflammatory models ketoprofen has been shown to have inhibitory effects on prostaglandin and leukotriene synthesis, to have antibradykinin activity, as well as to have lysosomal membrane-stabilizing action.

However, its mode of action, like that of other nonsteroidal anti-inflammatory drugs, is not fully understood.

Pharmacodynamics Ketoprofen is a racemate with only the S enantiomer possessing pharmacological activity.

The enantiomers have similar concentration time curves and do not appear to interact with one another.

An analgesic effect‑concentration relationship for ketoprofen was established in an oral surgery pain study with ketoprofen capsules.

The effect-site rate constant (K e0 ) was estimated to be 0.9 hour -1 (95% confidence limits: 0 to 2.1), and the concentration (Ce 50 ) of ketoprofen that produced one‑half the maximum PID (pain intensity difference) was 0.3 mcg/mL (95% confidence limits: 0.1 to 0.5).

Thirty-three to 68% of patients had an onset of action (as measured by reporting some pain relief) within 30 minutes following a single oral dose in postoperative pain and dysmenorrhea studies.

Pain relief (as measured by remedication) persisted for up to 6 hours in 26 to 72% of patients in these studies.

Pharmacokinetics General Ketoprofen extended-release capsules contain ketoprofen.

They differ only in their release characteristics.

Ketoprofen capsules release drug in stomach whereas ketoprofen extended-release capsules are designed to resist dissolution in the low pH of gastric fluid but release drug at a controlled rate in the higher pH environment of the small intestine (see DESCRIPTION ).

Irrespective of the pattern of release, the systemic availability (F s ) when either oral formulation is compared with IV administration is approximately 90% in humans.

For 75 to 200 mg single doses, the area under the curve has been shown to be dose proportional.

The figure depicts the plasma time curves associated with both products.

Ketoprofen is > 99% bound to plasma proteins, mainly to albumin.

Separate sections follow which delineate differences between ketoprofen capsules and ketoprofen extended-release capsules.

Absorption Ketoprofen capsules are rapidly and well-absorbed, with peak plasma levels occurring within 0.5 to 2 hours.

Ketoprofen extended-release capsules are also well-absorbed from this dosage form, although an observable increase in plasma levels does not occur until approximately 2 to 3 hours after taking the formulation.