Rapid Mucosal Absorption of Topical Lidocaine During Bronchoscopy in the Presence of Oral Candidiasis: Conclusion
These values are total concentrations, both bound and free lidocaine, and give no information about free fraction, which we did not investigate. The major plasma protein which binds lidocaine and several other basic drugs, alpha!-acid glycoprotein is an acute-phase protein that is elevated in certain situations such as stress, neoplastic disease, acute and chronic inflammatory diseases, hepatic damage, and trauma. The free fraction of lidocaine in plasma is inversely related to plasma AAG concentrations. This patients adenocarcinoma and trauma associated with chest tube insertion might have elevated his AAG concentrations and decreased the free fraction of lidocaine. That physiologic change might explain the absence of signs or symptoms of lidocaine toxicity.
Alterations in the rate and extent of absorption of topically applied drugs, such as salicylates and steroids, through abnormal skin have been reported in patients with psoriasis and ichthymosis and in models of experimentally-induced skin damage. Litde information exists, however, on the influence of superficial infections on topical absorption of chemicals applied to the skin. In superficial infections due to Candida, there can be histologic evidence of cell and tissue damage and ulcerative or necrotic lesions with deeper tissue involvement. Altered transfer of water and chemicals through the damaged skin might be expected.
Another recent case report suggests altered absorption of lidocaine jelly due to mucosal trauma. Although seizures occurred, plasma lidocaine levels did not substantiate altered absorption as the cause of the toxicity. Patients with topical fungal infections may be at greater risk of systemic toxicity from topically applied lidocaine and possibly other medications. The possibility of enhanced drug absorption through mucosa damaged by candidiasis warrants further study.