Pharmacology for Anaesthesia and Intensive Care

(Romina) #1

P1: PCX Printer: Yet To Come
9780521704632c09 CUFX213A/Peck 9780521618168 December 28, 2007 11:33


Section IICoredrugs in anaesthetic practice

effects including agranulocytosis and aplastic anaemia. It is significantly bound by
plasma proteins and will interact with other highly bound drugs. It may also impair
hepatic function, produce a rash, and cause sodium and water retention.

Proprionic acids
Ibuprofen
Ibuprofen is prepared as 200–600 mg tablets and as a paediatric elixir containing
20 mg.ml−^1 .Itisnot recommended for children below 1 year of age. The paediatric
dose is 20 mg.kg−^1 .day−^1 in divided doses. It has mild anti-inflammatory and anal-
gesic effects but has the lowest incidence of side effects of the most commonly used
NSAIDs.

Oxicams
Tenoxicam
Tenoxicam exhibits many of the features common with other NSAIDs. Two specific
features make it particularly useful in the peri-operative period:
Itmay be given intravenously resulting in a rapid onset of action.
Ithas a long elimination half-life (72 hours) resulting in a long duration of action
and allowing once-daily dosage.
However, these advantages may become disadvantages if side effects become sig-
nificant.

Kinetics
Tenoxicam is well absorbed from the gut and has a high oral bioavailability. It is
highly plasma protein bound (99%). Clearance from the body is due to metabolism
to an inactive metabolite that is excreted in the urine (66%) and in bile (33%). The
dose is 20 mg.day−^1.

Preferential COX–2 inhibitors
Meloxicam
Meloxicam is available as tablets and suppositories and the initial dose is 7.5
mg.day−^1 ,which may be doubled.
Meloxicam has limited preferential selectivity for COX-2 and is quoted as being
between 3 to 50 times as potent against COX-2. At a dose of 7.5 mg.day−^1 it
has a reduced gastrointestinal side-effect profile when compared with diclofenac,
although its renal side-effect profile appears to be equivalent to other NSAIDs.

Kinetics
Meloxicam is slowly but almost completely absorbed from the gut with an oral
bioavailability of 90%. It is 99% protein bound, essentially to albumin. Metabolism
occurs in the liver to inactive metabolites that are excreted in the urine (50%) and bile
Free download pdf