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Pregabalin as a Bully
Have you ever known someone who was a bully but surprised you by sticking up for the little guy? That's kind of how pregabalin is. It's a bully and you are the little guy. Why are you the little guy? Because you are in pain. Pain is picking on you and it won't leave you alone. Why does that make pregabalin a bully? Pregabalin is primarily indicated for use with pain related diagnoses. It can also be used as an anticonvulsant and has other off label uses. We will explore its mechanism of action to determine why, in this case, the bully has turned into the hero.
Mechanism of Action
Pain signals, along with those that cause convulsions or seizures, are passed from nerve to nerve through voltage-gated calcium channels that have alpha-delta subunits. Those with alpha-delta subunits are considered HVA or high voltage-activated channels. In the nerve cell, the calcium that passes through these channels excites the nerve cell and causes the transmission of the signal across the synapse to the next nerve cell.
The alpha-delta subunit can usually be found on the presynaptic section of nerve cells. What does that mean? The synapse, or the synaptic gap, is where a signal is passed from one nerve cell to another. So, if something blocks a signal in the presynaptic region of a cell, it modifies or stops the transmission of the signal to the next nerve. This is where pregabalin comes in, it binds to the subunit blocking the passing of calcium which reduces or stops the signal for pain or convulsions.
In our scenario, you are being picked on by pain, which is carried by calcium through the calcium channel. The door to the calcium channel is labeled the alpha-delta subunit. Pregabalin acts like a big bully to the pain because it blocks the door and refuses to let the calcium by. But, it is a hero to you because when it attaches to the door and refuses to let the pain by, it stops the pain signal.
Pregabalin's actions are described medically as antinociceptive and anticonvulsant. This means its actions prevent or reduce pain and convulsions. Some evidence shows that it may affect epinephrine and serotonin in the central nervous system, which includes the spinal cord and the brainstem.
Pharmacokinetics of Pregabalin
What exactly is pharmacokinetics? In science, kinetics refers to the study of motion and its causes. Combine this with pharmaco-, which deals with the use of drugs in medicine, and we get the study of how medicine moves through the body and what forces act on it causing it to do so. The primary categories of pharmacokinetics are absorption, distribution, and elimination. These categories can be further divided into more specific measures, such as time frames.
Absorption of Pregabalin
Pregabalin is taken by mouth with or without food and quickly absorbed in the stomach. The presence of food does slow the absorption of pregabalin but does not prevent it. In the end, the same amount is absorbed within approximately 40-80 minutes. Pregabalin is not a fast acting medicine, so since the same amount is absorbed ultimately, it does not matter if the patient has eaten or not.
Distribution of Pregabalin
Bioavailability describes how much of a medicine makes it from the point of administration into the blood stream. In the case of pregabalin, it is 90%. The volume of distribution helps the pharmacist and doctor determine the appropriate dose of the drug. Pregabalin's Vd or volume of distribution is 0.5 L/Kg. This gives the prescriber an idea of the volume needed for absorbing all of the medicine.
Pregabalin does not bind to proteins, like albumin, in the blood, and it is minimally metabolized. Once it is in the blood, it stays there until it reaches the point of action, the alpha-delta subunit. Once there, it does its job, blocking the door until it is excreted. This distribution is completed within 1.5 hours to 3 hours depending on whether it was taken with food. Although pregabalin is distributed quickly and evenly, it does not reach a level concentration for one to two days. Its effectiveness may not be seen until at least a week after dosing has begun.
A drug's half-life is the time it takes for its concentration to drop to half the original amount. In other words, how long, does it take for your body to get rid of half of the drug. For pregabalin, it is about six hours. Your kidneys do almost all the elimination of pregabalin. Because of this, the health of your kidney needs to be considered with pregabalin use. When pregabalin gets to your kidneys, 90% is almost completely the same as it went in, which indicates that most of it is not metabolized in the body.
Pregabalin is a medicine used primarily for pain but may be used to treat seizures and a few other off label indications. Pain signals are transmitted from nerve to nerve through calcium channels that have alpha-delta subunits. Pregabalin binds to this site, or door, before the synapse and prevents the calcium from passing through, blocking or reducing the pain.
Pregabalin's pharmacokinetics include absorption in the stomach without regard to food. 90% of the medicine is distributed into the blood stream within 1.5 to 3 hours. It takes 1 - 2 days to reach a steady level and up to a week before effectiveness can be noted. 90% of pregabalin is excreted by the kidneys in its original form, therefore it is mostly non-metabolized. Adequate kidney function is important with pregabalin use.
MEDICAL DISCLAIMER: The information on this site is for your information only and is not a substitute for professional medical advice.
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