ABSTRACT
Labetalol 0.85 40 Changes in liver blood flow associated with liver disease affect these drugs The shunting of blood that bypasses the liver has important effects on bioavailability.
Verapamil 0.80 92
Morphine 0.75 35
Propranolol 0.65 95
Lignocaine (lidocaine)
0.60 65
Flow-and capacity-sensitive drugs
Metoprolol 0.56 10 Changes in both liver blood flow and free fraction of drug in the blood may be important for this class of drugs
Methohexitone 0.53 70
Pethidine 0.50 70
Paracetamol 0.30 20
Chlorpromazine 0.30 95
Ranitidine 0.28 15
Capacity-limited, binding-sensitive drugs
Diphenylhydantoin 0.03 92 This class of drugs will be considerably influenced by changes in protein binding
Chlordiazepoxide 0.02 96
Diazepam 0.02 97
Warfarin 0.005 99
Capacity-limited, binding-insensitive drugs
Hexobarbitone 0.15 47 This class of drugs will not be influenced much by changes in protein binding
Antipyrine 0.05 10
Theophylline 0.05 62
Caffeine 0.04 31
Figure 28.15 The plasma protein binding of some drugs used in anaesthesia. (Adapted from Jorm CM and Stamford SA. Ballière’s Clin Anaesthesiol 1992;6:751; Wood M.Anaesth Analg 1986;65:786.)
Figure 28.16 The relationship between flow-limited and capacitylimited drug metabolism and the hepatic extraction ratio. This diagram is often referred to as Blaschke’s triangle.
