On with the grand unveiling:
This week the featured drug belongs to a group of medicines known as anticonvulsants. Anticonvulsants are defined as, 'medications that are used to prevent seizures or stop a series of on-going seizures'. (http://www.medterms.com/script/main/art.asp?articlekey=20523)
This is in honor of a patient that I took care of not too long ago and I got to see again today. He is a cute little guy and he and I hit it off, but unfortunately we did not meet under good circumstances. This guy has a pretty severe seizure disorder and anticonvulsant medications are used to treat his seizures.
The anticonvulsant of choice shall be: Neurontin, or Gabapentin (we will just call it Neurontin for simplicity sake).
I also have another motive in discussing this medication as I have personal experience with it. In an old job of mine I worked with the developmentally disabled and one of my clients was on this particular medication. The rules in Utah are funny: if I were giving medication to an intellectually capable person it would have been far outside of my scope of practice, but as my clients were not fully capable of understanding what was going on, it was suddenly appropriate for me to give them the medicine, and they took it. The days when this client either neglected or was not able to take his medication he had a great deal more seizures, so at least in his case, it proved effective.
The Neurontin molecule looks like this:
This molecule is considerably less complex than some we have looked at before. I wanted to find a space-filling molecule, but information on this drug is surprisingly lean. I was able to find, though a series of graphs from a clinical trial of Neurontin on nerve pain,
'The proportion of responders (those patients reporting at least 50% improvement in endpoint pain score compared with baseline) was calculated for each study' (http://www.healthyplace.com/other-info/psychiatric-medications/gabapentin-neurontin-full-prescribing-information/menu-id-122/
I was also able to find this 'chart' which shows the side-effects of Neurontin as compared to a Placebo. Some points of clarification as to the chart:
'The most commonly observed adverse events associated with the use of Neurontin in adults, not seen at an equivalent frequency among placebo-treated patients, were dizziness, somnolence, and peripheral edema.
In the 2 controlled studies in postherpetic neuralgia, 16% of the 336 patients who received Neurontin and 9% of the 227 patients who received placebo discontinued treatment because of an adverse event. The adverse events that most frequently led to withdrawal in Neurontin-treated patients were dizziness, somnolence, and nausea.
Table 2 lists treatment-emergent signs and symptoms that occurred in at least 1% of Neurontin-treated patients with postherpetic neuralgia participating in placebo-controlled trials and that were numerically more frequent in the Neurontin group than in the placebo group. Adverse events were usually mild to moderate in intensity.'
| 'Body System/ | Neurontin | Placebo |
|---|---|---|
| Preferred Term | N=336 % | N=227 % |
| ||
| Body as a Whole | ||
| Asthenia | 5.7 | 4.8 |
| Infection | 5.1 | 3.5 |
| Headache | 3.3 | 3.1 |
| Accidental injury | 3.3 | 1.3 |
| Abdominal pain | 2.7 | 2.6 |
| Digestive System | ||
| Diarrhea | 5.7 | 3.1 |
| Dry mouth | 4.8 | 1.3 |
| Constipation | 3.9 | 1.8 |
| Nausea | 3.9 | 3.1 |
| Vomiting | 3.3 | 1.8 |
| Flatulence | 2.1 | 1.8 |
| Metabolic and Nutritional Disorders | ||
| Peripheral edema | 8.3 | 2.2 |
| Weight gain | 1.8 | 0.0 |
| Hyperglycemia | 1.2 | 0.4 |
| Nervous System | ||
| Dizziness | 28.0 | 7.5 |
| Somnolence | 21.4 | 5.3 |
| Ataxia | 3.3 | 0.0 |
| Thinking abnormal | 2.7 | 0.0 |
| Abnormal gait | 1.5 | 0.0 |
| Incoordination | 1.5 | 0.0 |
| Amnesia | 1.2 | 0.9 |
| Hypesthesia | 1.2 | 0.9 |
| Respiratory System | ||
| Pharyngitis | 1.2 | 0.4 |
| Skin and Appendages | ||
| Rash | 1.2 | 0.9 |
| Special Senses | ||
| Amblyopia* | 2.7 | 0.9 |
| Conjunctivitis | 1.2 | 0.0 |
| Diplopia | 1.2 | 0.0 |
| Otitis media | 1.2 | 0.0' |
This webpage, if I am not mistaken, is where government drug trials are reported. This was a great resource in terms of finding other information about this drug. There were even data tables discussing the differences between adult reported side-effects and pediatric side-effects. But, my space is short, so I picked only one of the graphs. A further look at this drug and the information found on that page is definitely worth it.
Neurontin has wide ranging uses. Sometimes it is administered as an anti-migraine medicine, sometimes for control of neuropathic pain, seizure control or it has even been used as a therapy for pain control after a case of the shingles has developed (http://www.neurontingabapentin.com/information.shtml).
(I would love to be able to use the opinions found on www.rateadrug.com for other insight into this medication, but there have been no surveys completed about Neurontin specifically. This is something I will have to work on with my co-workers. The more information the better!)
According to information from Pfizer, the maker of Neurontin,
'The mechanism by which gabapentin exerts its anticonvulsant action is unknown...' And, 'The mechanism by which gabapentin exerts its analgesic action is unknown...' It is, however, suspected that Neuronton acts in the way that it does by mimicking a certain transmitter known as GABA (gamma-aminobutyric acid), but it is not converted into it, nor does it react in quite the same way.
'In vitro studies with radiolabeled gabapentin [Neurontin] have revealed a gabapentin binding site in areas of rat brain including neocortex and hippocampus. A high-affinity binding protein in animal brain tissue has been identified as an auxiliary subunit of voltage-activated calcium channels. However, functional correlates of gabapentin binding, if any, remain to be elucidated.'
(http://www.pfizer.com/files/products/uspi_neurontin.pdf)
So, after searching the internet for some time I have found that Pfizer, the maker of Neurontin, openly admits that they do not fully understand how this drug functions. On the outset that seems to be a little disconcerting, but from personal experience I can assure you this drug does work. I have seen it administered for seizure activity and for neuropathic pain and it has been effective in both cases.
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