A Comparison of SSRIs and SNRIs
Posted 04-06-2008 at 09:54 PM by ladypam
Depression is a disorder afflicting many people nowadays and there are a lot of medications being made for it. Since the mechanism for this disorder has not yet been fully recognized, its treatment has been directed into different aspects of it. The basis of several antidepressants has been directed into the substances that are found in the synaptic cleft
between nerve cells, which are called neurotransmitters. These neurotransmitters have been found to affect the way the signals are transmitted from one nerve cell to another.
When problems occur with these neurotransmitters, then several disorders crop up with the nervous processes. And it is here where these new medications act on, although with different effects. For the treatment of depression, scientists have come up with two medications: the older Selective Serotonin Uptake Inhibitors or SSRIs and the newer one, Serotonin Norepinephrine Uptake Inhibitors or SNRIs.
These two medications have a lot in common with the most specific of all is the ability to inhibit the uptake of serotonin into the releasing nerve cell or presynaptic nerve cell. During synapse, under normal conditions, the presynaptic nerve cell releases neurotransmitters, including serotonin, into the synaptic cleft which is the space between the two nerve cells. These neurotransmitters get attracted to their specific receptors found in the receiving nerve cell or the postsynaptic nerve cell. When these receptors have been filled with neurotransmitters, the remaining neurotransmitters get taken back by the presynaptic nerve cell by the process which we know as reuptake and the neurotransmitters bound to the receptors activate the postsynaptic nerve cell to release neurotransmitters to the next nerve cell. This process goes on and on until it reaches its target organ.
However, there are times that the postsynaptic nerve cell has a hard time getting stimulation. Since the reuptake process removes almost all traces of the neurotransmitters, they have no chance of attracting them via their receptors. With SSRIs and SNRIs, when the serotonin is released by the presynaptic nerve cell, it attaches itself to the transporter proteins that are responsible for the reuptake of neurotransmitters. This in turn inhibits serotonin from getting back into the presynaptic nerve cell and they remain within the synaptic cleft. This increased level of serotonin in the synaptic cleft bombards the receptors in the postsynaptic nerve cell until they become stimulated enough to accept the serotonin and other neurotransmitters.
But you may ask what happens to the increase in serotonin in the synaptic cleft? The serotonin that remains in the synaptic cleft triggers a regulation mechanism in the presynaptic nerve cell to stop the production of serotonin. It also triggers another regulation mechanism or more specifically a deregulation mechanism in the post synaptic nerve cell that adjusts the number of receptors to at least equal the number of serotonin molecules available. With this deregulation mechanism, it is not just ratio of receptors and serotonin molecules that are important but the number of pairs it can produce since it is based on the percentage of activation. This percentage of activation is what determines the length of time that full relief is received from the antidepressant used.
Both medications use this mechanism of action to treat depression although with SNRIs, it is not only limited to serotonin levels but to norepinephrine as well which is responsible for the resolution of neuropathic pain.
The side effects of both medications are quite similar because of the same mechanism that they use. Common side effects are drowsiness, nausea, headaches, variations in appetite, having vivid and explicit dreams, as well as sexual side effects. With these antidepressants, even the libido or interest in having sex is decreased since there is also a decrease in the ability to reach orgasm or climax. Having an erection is not a problem with these drugs although its staying power is sometimes not enough to satisfy their partner. And this problem sometimes leads to patients discontinuing the antidepressant that they are using and taking other brands like nefazodone or Serzone that do not affect the sexual activity of the patient.
With SNRIs, it causes additional side effects due to the presence of norepinephrine. This drug has the ability to cause activation, anxiety and an increase in blood pressure. This is the reason why people taking SNRIs are recommended to have their blood pressures monitored at least twice a day so as to avoid sudden increases in blood pressure.
Both SSRIs and SNRIs cannot be used together with antidepressants made of monoamine oxidase inhibitors since it produces adverse effects between them. St. John’s wort has also been seen to react with these medications.
These antidepressants also have a high toxic dose level as compared to other antidepressants. This means that it safe for those patients planning to kill themselves through taking an overdose. Unfortunately, there are some medications that may increase the toxicity of these antidepressants. This includes alcoholic products, diuretics, monoamine oxidase inhibitor drugs, lithium, ecstasy or MDMA, sympathomimetic drugs including pseudoephedrine, sibutramine, zolpiderm and dextromethrophan.
The dosage schedule of these two antidepressants should not be altered before consulting your doctor since an abrupt stop of these medications may cause a discontinuation syndrome which comprises withdrawal symptoms that may be quite uncomfortable for the person.
The use of SSRIs is quite popular with several of its brand a common name in several households. But SNRIs are now catching up fast since it does not only have antidepressive properties but also tackles the problem on neuropathic pain which also gives a cause for concern for those patients.
With the increase of patients developing depression at present, several medications are being introduced with claims of being the best one in the market. Being the newest at this time, SNRIs only have a few available brands. But it has already garnered positive responses from a lot of patients who have tried it out.
Selective Serotonin Reuptake Inhibitors and Serotonin Norepinephrine Reuptake Inhibitors all affect the nerve cells of patients with depression. With a big number of antidepressants wanting to give a hand in its treatment, it is hard to decide which one. Remember that it is not the medication that will have to adjust but the person receiving them.
between nerve cells, which are called neurotransmitters. These neurotransmitters have been found to affect the way the signals are transmitted from one nerve cell to another.
When problems occur with these neurotransmitters, then several disorders crop up with the nervous processes. And it is here where these new medications act on, although with different effects. For the treatment of depression, scientists have come up with two medications: the older Selective Serotonin Uptake Inhibitors or SSRIs and the newer one, Serotonin Norepinephrine Uptake Inhibitors or SNRIs.
These two medications have a lot in common with the most specific of all is the ability to inhibit the uptake of serotonin into the releasing nerve cell or presynaptic nerve cell. During synapse, under normal conditions, the presynaptic nerve cell releases neurotransmitters, including serotonin, into the synaptic cleft which is the space between the two nerve cells. These neurotransmitters get attracted to their specific receptors found in the receiving nerve cell or the postsynaptic nerve cell. When these receptors have been filled with neurotransmitters, the remaining neurotransmitters get taken back by the presynaptic nerve cell by the process which we know as reuptake and the neurotransmitters bound to the receptors activate the postsynaptic nerve cell to release neurotransmitters to the next nerve cell. This process goes on and on until it reaches its target organ.
However, there are times that the postsynaptic nerve cell has a hard time getting stimulation. Since the reuptake process removes almost all traces of the neurotransmitters, they have no chance of attracting them via their receptors. With SSRIs and SNRIs, when the serotonin is released by the presynaptic nerve cell, it attaches itself to the transporter proteins that are responsible for the reuptake of neurotransmitters. This in turn inhibits serotonin from getting back into the presynaptic nerve cell and they remain within the synaptic cleft. This increased level of serotonin in the synaptic cleft bombards the receptors in the postsynaptic nerve cell until they become stimulated enough to accept the serotonin and other neurotransmitters.
But you may ask what happens to the increase in serotonin in the synaptic cleft? The serotonin that remains in the synaptic cleft triggers a regulation mechanism in the presynaptic nerve cell to stop the production of serotonin. It also triggers another regulation mechanism or more specifically a deregulation mechanism in the post synaptic nerve cell that adjusts the number of receptors to at least equal the number of serotonin molecules available. With this deregulation mechanism, it is not just ratio of receptors and serotonin molecules that are important but the number of pairs it can produce since it is based on the percentage of activation. This percentage of activation is what determines the length of time that full relief is received from the antidepressant used.
Both medications use this mechanism of action to treat depression although with SNRIs, it is not only limited to serotonin levels but to norepinephrine as well which is responsible for the resolution of neuropathic pain.
The side effects of both medications are quite similar because of the same mechanism that they use. Common side effects are drowsiness, nausea, headaches, variations in appetite, having vivid and explicit dreams, as well as sexual side effects. With these antidepressants, even the libido or interest in having sex is decreased since there is also a decrease in the ability to reach orgasm or climax. Having an erection is not a problem with these drugs although its staying power is sometimes not enough to satisfy their partner. And this problem sometimes leads to patients discontinuing the antidepressant that they are using and taking other brands like nefazodone or Serzone that do not affect the sexual activity of the patient.
With SNRIs, it causes additional side effects due to the presence of norepinephrine. This drug has the ability to cause activation, anxiety and an increase in blood pressure. This is the reason why people taking SNRIs are recommended to have their blood pressures monitored at least twice a day so as to avoid sudden increases in blood pressure.
Both SSRIs and SNRIs cannot be used together with antidepressants made of monoamine oxidase inhibitors since it produces adverse effects between them. St. John’s wort has also been seen to react with these medications.
These antidepressants also have a high toxic dose level as compared to other antidepressants. This means that it safe for those patients planning to kill themselves through taking an overdose. Unfortunately, there are some medications that may increase the toxicity of these antidepressants. This includes alcoholic products, diuretics, monoamine oxidase inhibitor drugs, lithium, ecstasy or MDMA, sympathomimetic drugs including pseudoephedrine, sibutramine, zolpiderm and dextromethrophan.
The dosage schedule of these two antidepressants should not be altered before consulting your doctor since an abrupt stop of these medications may cause a discontinuation syndrome which comprises withdrawal symptoms that may be quite uncomfortable for the person.
The use of SSRIs is quite popular with several of its brand a common name in several households. But SNRIs are now catching up fast since it does not only have antidepressive properties but also tackles the problem on neuropathic pain which also gives a cause for concern for those patients.
With the increase of patients developing depression at present, several medications are being introduced with claims of being the best one in the market. Being the newest at this time, SNRIs only have a few available brands. But it has already garnered positive responses from a lot of patients who have tried it out.
Selective Serotonin Reuptake Inhibitors and Serotonin Norepinephrine Reuptake Inhibitors all affect the nerve cells of patients with depression. With a big number of antidepressants wanting to give a hand in its treatment, it is hard to decide which one. Remember that it is not the medication that will have to adjust but the person receiving them.
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