Pharmacokinetics
Absorption
Vinpocetine, the active ingredient of Cavinton 5mg, is rapidly absorbed, with peak serum concentration achieved one hour after ingestion. The primary absorption site is in the proximal part of the digestive system. Interestingly, this compound is not metabolized when passing through the intestine.
Distribution
Studies conducted on mice using radiolabeled medication reveal that vinpocetine has high concentrations in the liver and digestive system. Maximum concentrations in tissue can be measured 2-4 hours after ingestion. The concentration of the radiolabeled substance in the brain is not higher than that in the blood. In humans, 66% of vinpocetine is bound to proteins. The absolute oral bioavailability is 7%. The distribution volume is 246.7+88.5 liters, indicating significant tissue binding. The elimination clearance of vinpocetine (66.7 l/hour) exceeds the serum clearance of the liver (50 l/hour), suggesting metabolism outside the liver.
Excretion
Repeated dosing of 5mg and 10mg doses of vinpocetine shows linear kinetics; the serum concentration at steady state is 1.2±0.27 ng/ml and 2.1±0.33 ng/ml, respectively. The elimination half-life in humans is 4.83±1.29 hours. Studies conducted with radiolabeled substances reveal that the primary excretion route is through urine and feces in a 60/40 ratio. Most radiolabeled substances originate from bile in mice and dogs, but significant enterohepatic circulation has not been confirmed. Apovincamic acid is eliminated through the kidneys via simple renal filtration, with elimination half-life depending on the dose and route of vinpocetine administration.
Metabolism
The main metabolite of vinpocetine is apovincaminic acid (AVA), which is produced in humans at a rate of 25-30%. After ingestion, the area under the AVA concentration curve is twice as large as after intravenous injection, indicating first-pass metabolism. Other identified metabolites include hydroxyvinpocetine, hydroxy-AVA, dihydroxy-AVA glycinate, and their conjugates with glucuronide and/or sulfate. In the studied species, the amount of vinpocetine excreted as unchanged compound only accounts for a small percentage of the administered dose.
Advantages and Importance of Vinpocetine
A significant advantage of vinpocetine is that no dose adjustment is needed for patients with renal or liver impairment because it does not accumulate. The daily dose ranges from 1 to 2 tablets of Cavinton 5mg three times a day (15mg-30mg per day) or 1 tablet of Cavinton Forte three times a day.
Changes in Pharmacokinetic Characteristics under Specific Conditions
Since vinpocetine is mainly indicated for the treatment of elderly patients, who may experience altered drug kinetics, such as reduced absorption, distribution, metabolism, and excretion, it is crucial to conduct pharmacokinetic studies in this age group, especially with long-term medication use. Research results have shown that the pharmacokinetics of vinpocetine in elderly individuals does not differ significantly from younger individuals and does not lead to drug accumulation. In cases of impaired liver and kidney function, using the regular dose is still possible as vinpocetine does not accumulate, allowing for long-term treatment.
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