1. Interaction of physostigmine and alfentanil in a human pain model†
A.P. Wehrfritz, H. Ihmsen, S. Schmidt, C. Müller, J. Filitz, J. Schüttler, W. Koppert 
British Journal of Anaesthesia 
Volume 104, Issue 3, Pages (March 2010)
DOI: /bja/aep372
Copyright © 2010 The Author(s) Terms and Conditions

2. Fig 1
Schematic illustration of the experimental protocol. Four separate treatment trials were performed. The subjects received i.v. infusions of physostigmine, alfentanil, a combination of both, or saline as a control in a randomized order. The drugs were delivered by a continuous infusion lasting 15 min (physostigmine) or 2 min (alfentanil) and starting 30 min (physostigmine) or 35 min (alfentanil) after the onset of the electrical stimulation.
British Journal of Anaesthesia  , DOI: ( /bja/aep372)
Copyright © 2010 The Author(s) Terms and Conditions

3. Fig 2
Pain ratings (a) and the areas of pinprick-hyperalgesia (b) for the four treatments. Data were normalized to baseline and are expressed as mean±se.
British Journal of Anaesthesia  , DOI: ( /bja/aep372)
Copyright © 2010 The Author(s) Terms and Conditions

4. Fig 3
Measured and predicted time courses of the analgesic effect after administration of alfentanil and physostigmine for the two tested interaction models. Model 1, as defined by equations (3) and (4), was less appropriate than model 2, as defined by equations (6) and (7).
British Journal of Anaesthesia  , DOI: ( /bja/aep372)
Copyright © 2010 The Author(s) Terms and Conditions

5. Fig 4
Placebo-corrected and normalized analgesic (a–c) and antihyperalgesic (d–f) effects for alfentanil (a, d), physostigmine (b, e), and a combination of both (c, f), respectively. The predictions of the final pharmacodynamic model are drawn with solid lines. Data are expressed as mean±se.
British Journal of Anaesthesia  , DOI: ( /bja/aep372)
Copyright © 2010 The Author(s) Terms and Conditions

6. Fig 5
Isoboles for half-maximum analgesic (a) and antihyperalgesic (b) effect. The thin lines are the isoboles of the individual subjects, the bold line is the isobole obtained with the population parameters. The dashed line shows the line of additive interaction.
British Journal of Anaesthesia  , DOI: ( /bja/aep372)
Copyright © 2010 The Author(s) Terms and Conditions

7. Fig 6
Dose–response curves for the analgesic (a) and antihyperalgesic (b) effect of alfentanil and physostigmine.
British Journal of Anaesthesia  , DOI: ( /bja/aep372)
Copyright © 2010 The Author(s) Terms and Conditions