When taking Covonia lozenges Lemon the active ingredients are generally released very gradually and they act locally. Small amounts may enter the digestive system if saliva is swallowed.
Chlorhexidine
Absorption
In oral or topical use, absorption of chlorhexidine is insignificant.
In topical use on intact skin, chlorhexidine is adsorbed on the outside layers of the skin, providing long-term antimicrobial effect. Pharmacokinetic research has shown that after rinsing the oral cavity, approximately 30% of chlorhexidine is retained, which is then slowly released into the saliva.
Distribution
Chlorhexidine binds tightly to saliva proteins.
Biotransformation
Chlorhexidine is not accumulated in the body. Very little of it is metabolised.
Elimination
Following ingestion of a 300 mg dose of chlorhexidine gluconate approximately 90 % is excreted in faeces via biliary routes and less than 1 % is eliminated into urine.
Lidocaine
Absorption
Lidocaine absorption varies, depending on the site and the method of use. It is quickly resorbed from the digestive organs, mucous membranes and through damaged skin.
In healthy adults, no detectable plasma lidocaine levels were noted after use of a 2 % mouth rinse. Children and immune impaired adults do resorb lidocaine from the oral mucosa into the plasma. The levels were approximately 0,2 µ g/ml but the toxic plasma concentration is 5 µ g/ml. The anaesthetic effect of lidocaine after topical use appears 2 to 5 minutes after application and lasts 30 to 45 minutes. The anaesthetic effect is limited to the surface and does not extend to the submucosal structures.
Distribution
Lidocaine is distributed well in the tissues (kidneys, lungs, liver, heart, adipose tissue).
Lidocaine passes through the blood-brain barrier and placenta and into mother's milk.
Biotransformation
It is metabolised during the first pass through the liver and the bioavailability is about 35 % after oral administration. 90 % is deethylated in the liver to monoethylglycinexylide and glycinexylide. Both primary metabolites are pharmacologically active. Further cleavage of the amide bonds forms the metabolites xylidine and 4-hydroxyxylidine.
Elimination
Lidocaine is eliminated in the form of metabolites through the kidneys. Approximately 10% is eliminated unchanged. The biological half-life of lidocaine is one and a half to two hours in adults. The biological half-life of the primary metabolites is two to ten hours.