Why won't you start me on 800 mg if that is the tablet the pharmacy has?
Later rung: 800 mg is not a first-night swallow
OP-05 locks 800 mg as a later Neurontin tablet. The starter cards are 100 mg and 300 mg.
Climb the labeled stairs before you praise an 800 mg generic. Capsules come as 100, 300, and 400 mg. Tablets come as 600 and 800 mg. Solution is 250 mg in 5 mL. Night one in adult PHN is a single 300 mg swallow. An 800 mg tablet is how you hold a later total, not how you introduce the drug to a dizzy-prone reader.
Day one is a single 300 mg dose when the job is postherpetic neuralgia. Day two is 600 mg split. Day three is 900 mg in three swallows. Then you may climb toward 1800 mg/day - 600 mg three times - which is where the PHN studies showed a clear effect. Higher totals to 3600 mg/day were studied; extra benefit above 1800 was not shown.
Epilepsy in teens opens at 300 mg three times daily and may rise to 600 mg three times. Gaps must stay inside twelve hours. I have watched people jump to an 800 mg tablet because a review called it 'the strong one.' That skip is how somnolence and unsteadiness arrive on night one instead of week two.
What an 800 mg Neurontin later rung costs after titration
| Pharmacy | Strength / count | How the window works | Official page |
|---|---|---|---|
| Publix | 800 mg x 90 | Grocery pharmacy cash window | Publix pharmacy |
| Amazon Pharmacy | 800 mg x 90 | Mail pharmacy, not a store aisle | Amazon Pharmacy pharmacy |
| Meijer | 800 mg x 90 | Midwest grocery pharmacy desk | Meijer pharmacy |
| Albertsons | 800 mg x 90 | Grocery pharmacy cash window | Albertsons pharmacy |
Cash windows quote ninety of the 800 mg generics at four licensed US counters in the strip below - Publix, Amazon Pharmacy, Meijer, Albertsons. Each name opens that chain only. I will not drop a dollar into this prose. Coupon prints move by ZIP. This Dublin desk does not fill.
This clinic does not fill, and it does not treat an 800 mg ninety-count as a starter pack. If a review site sells you night-one 800s, they skipped the stairs. Titration still begins at 300 mg unless a kidney line says otherwise. Cost after titration means you already live on a later total.
Readers who want a cheaper opener should ask about 300 mg capsules, not a broken 800. Splitting scored tablets is allowed; inventing a paediatric crumb from an 800 is not a plan I will sign. Bring the creatinine and the opioid list to your own clinician before anyone changes a rung.
Dizziness is common. Sleep is not the indication.
Dizziness hit twenty-eight percent in PHN trials on Neurontin versus 8 percent on placebo, at totals up to 3600 mg/day. Somnolence was 21 versus 5 percent. Those two led the stop list. Epilepsy rooms over age twelve saw somnolence 19 versus 9, dizziness 17 versus 7, ataxia 13 versus 6, plus fatigue and nystagmus. Peripheral edema belongs on the PHN list too.
Somnolence is an adverse reaction, not a sleep licence. People ask for an 800 mg 'so I can finally knock out.' That is how a later rung becomes a homemade hypnotic, then a morning hangover, then a fall. I will not sign a card that treats Neurontin as a cleaner zolpidem. If insomnia is the complaint, say so in a sleep clinic, not as a titration review.
Driving should wait until you know how the drug sits in you. People are bad at judging their own sedation - the label says that out loud. Children three to twelve can show hostility, emotional lability, and concentration trouble. I mention it because parents hear 'nerve tablet' and miss the behaviour watch.
Opioids plus this later rung can slow the breath
Stacks I ask about before an 800 mg hold
- Opioids - morphine, hydrocodone, oxycodone, buprenorphine named on the label
- Other CNS depressants - benzodiazepines, z-drugs, leftover 'sleeping tablets'
- Underlying respiratory disease or older age - start lower, watch longer
- Slow breathing, long pauses, blue lips, hard to rouse - emergency, not a dose debate
Opioids plus gabapentin can slow or stop breathing. The warning sits on case reports, human work, and animal work. Morphine, hydrocodone, oxycodone, and buprenorphine are named. COPD, older lungs, and any other sedative stack raise the same worry. When I still co-prescribe, I start low and I tell a housemate what slow breathing looks like.
Morphine raised gabapentin exposure by about 44 percent in interaction work. Hydrocodone shifted peaks a few percent the other way and lifted gabapentin AUC about 14 percent. Those numbers are not permission to ignore the respiratory line. They are why a later 800 mg rung on top of a new opioid can feel like a different drug.
COPD and older lungs already run a narrow respiratory reserve. I treat that as a reason to stay on 300 mg steps longer, not a reason to jump to 800 mg because 'pain is still there.' Alcohol and night sedatives belong in the same sentence. If nobody at home can wake the reader, the combination is the problem, not a mysterious 'weak chest.'
Do not slam an 800 mg door
Slamming an 800 mg tablet habit overnight is a labeled risk. If you reduce, stop, or swap, do it over at least one week, longer if the prescriber says so. Abrupt or rapid stops have been tied to more seizures, withdrawal symptoms, and suicidal thoughts or acts. That last line is easy to skip in a pain clinic. I do not skip it.
Withdrawal and extra seizures show up when someone treats Neurontin like a vitamin they can ghost. Even readers who never had epilepsy can feel a rebound week - agitation, insomnia, sweat, pain that feels louder. People with a seizure history get a harder version of that week. Plan the down-ramp before you celebrate a 'pain-free' month.
Suicidal thinking is a class watch on antiepileptic drugs, gabapentin included. Families should hear it once in plain words: new gloom, restlessness, or talk of death is a same-week call, not a 'give it time' note. DRESS, anaphylaxis, and angioedema are the rare slam-shut immunologic doors - fever, rash, swollen nodes, swollen lips or tongue. Those are stop-and-evaluate, not taper-over-tea.
Two labeled rooms, a wide off-label hallway
1993
US approval as Neurontin, first as an epilepsy adjunct.
2002
Adult postherpetic neuralgia joins the stamp.
2004+
Off-label marketing fights taught a generation to write it for almost any nerve complaint.
2019
Respiratory depression warning with CNS depressants, especially opioids.
Labeled rooms are postherpetic neuralgia in adults and adjunctive therapy for partial-onset seizures, with or without secondary generalization, from age three. That is the Neurontin licence. Everything else is a hallway: diabetic nerve pain, restless legs, anxiety, migraine prevention, alcohol use, perioperative pain, hot flushes. Some hallways have decent trials. Many have habit.
Diabetic nerve pain sits off this exact Neurontin stamp even though clinics write it daily. Restless-legs products that use gabapentin enacarbil are not this tablet. Gralise is a once-daily PHN gabapentin that is not milligram-interchangeable with Neurontin. I will not swap an 800 mg Neurontin for either of those and call it 'the same GABA.'
Horizant and Gralise are not this card. Off-label sprawl after the 1990s marketing years left a generation of reviews that treat gabapentin as universal nerve oil. The uses and evidence study is where I park that argument. This profile stays on the 800 mg later rung and the two labeled jobs.
Saturable gut: more milligrams, less of each milligram
Absorption
Oral; saturable L-amino-acid-type transport. Bioavailability falls as the daily total climbs (about 60% at 900 mg/day to about 27% at 4800 mg/day in three splits). Food ~14% higher AUC.
Distribution
Less than 3% protein bound. Apparent volume ~58 L after 150 mg IV. CSF troughs ~20% of plasma in epilepsy.
Metabolism
Not appreciably metabolized. Parent compound does the work.
Excretion
Unchanged in urine. Half-life 5-7 hours when kidneys work. Clearance tracks creatinine clearance. Dialyzable.
Lilac titration marks
Starter300 mg, not 800 mg
Later tablet800 mg scored
Half-life5-7 hours
FoodAllowed; small AUC bump
AntacidAbout 20% less absorbed; 2-hour gap helps
Saturable gut transporters cap how much of a swallow you actually absorb. Bioavailability is about 60 percent at 900 mg/day in three splits, then 47 percent at 1200, 34 percent at 2400, 33 percent at 3600, and 27 percent at 4800. Doubling the tablet does not double the blood. That is why I rarely chase a stubborn pain with ever-larger 800s.
Food barely moves the curve - about 14 percent higher AUC and peak. Protein binding stays under 3 percent. Apparent volume after a small IV dose sat near 58 L. CSF troughs in epilepsy were about 20 percent of plasma. Half-life is 5 to 7 hours and does not stretch with repeat labeled dosing in people with working kidneys.
Three times daily keeps gaps inside twelve hours so the trough does not fall off a cliff. Aluminium-magnesium antacid cut mean bioavailability about 20 percent; waiting two hours after the antacid recovered about half that loss. Probenecid did not change the picture, which fits a drug that is not riding that tubular-secretion path.
From a 300 mg first step to an 800 mg hold
| Day or job | Typical labeled move | Where 800 mg sits |
|---|---|---|
| PHN day 1 | 300 mg once | Not here |
| PHN day 2 | 300 mg twice (600 mg/day) | Not here |
| PHN day 3 | 300 mg three times (900 mg/day) | Still a 300 mg capsule job |
| Later PHN hold | Toward 1800 mg/day in three splits | 600 or 800 mg tablets can hold the split |
| Epilepsy ≥12 y start | 300 mg three times daily | 800 mg is a later tablet, not the opener |
Adult PHN titration is a three-day ramp, then a slower climb. I do not hand an 800 mg tablet to someone who has never met 300 mg. If they later split a scored 800, the unused half belongs in the next dose and should be thrown out after 28 days. That half-tablet rule is on the label, not a forum habit.
Maintenance in epilepsy for people twelve and older sits at 300 to 600 mg three times daily. Long-term rooms have used 2400 mg/day. A few short stays used 3600 mg/day. Children three to four years aim near 40 mg/kg/day in three splits after a 10-15 mg/kg/day start. Ages five to eleven aim 25-35 mg/kg/day. Those paediatric numbers never become an adult 800 mg excuse.
Swallow capsules whole with water. Food is allowed. I still ask what else is on the night table - oxycodone, a benzodiazepine, wine - because the 800 mg rung is where people feel 'settled' and start stacking. Settled can mean sedated.
Kidneys set the ceiling, not the review stars
| CrCl (mL/min) | Total daily band | Usual rhythm |
|---|---|---|
| ≥60 | 900-3600 mg | Three times daily |
| >30 to 59 | 400-1400 mg | Twice daily |
| >15 to 29 | 200-700 mg | Once daily |
| 15 | 100-300 mg | Once daily |
| <15 | Proportion of the 15 band | Once daily |
| Hemodialysis | Maintenance by residual CrCl | Plus 125-350 mg after 4 h dialysis |
Kidneys write the real ceiling because gabapentin leaves as unchanged drug. Creatinine clearance at or above 60 mL/min still allows the 900-3600 mg/day band in three doses. Between 30 and 59 the daily band drops to 400-1400 and the rhythm becomes twice daily. That is where an 800 mg tablet can suddenly be a full day, not a split.
Creatinine clearance under sixty forces a smaller total and a slower clock. Fifteen to 29 mL/min sits at 200-700 mg once daily. At 15 mL/min the band is 100-300 mg once daily, and below 15 you shrink in proportion - 7.5 mL/min is half of the 15 mL/min day. Elderly clearance falls mostly because the kidneys fall. Age alone is not a second table.
Hemodialysis days need a supplemental swallow after each four-hour run, on top of the maintenance guessed from residual clearance. Supplements on the label run 125 to 350 mg. Anuric half-life stretched to about 132 hours off dialysis and collapsed during the run. I do not leave an 800 mg habit untouched when dialysis starts.
Sign-out from the later 800 mg rung
Sign-out leaves the 800 mg tablet where it belongs: after a 300 mg start, after kidneys have spoken, after someone has named the opioid stack, and after a taper plan exists. PHN and adjunctive partial seizures are the labeled rooms. Sleep is not one of them.
Ask your own clinician before you jump a rung or stop a habit. This Merrion Square card is teaching. Saoirse Byrne has not examined you. The live Neurontin label still wins if a line here ages.
Last Updated
Ask the doctor
Consulting room questions
Answered by Dr. Saoirse Byrne, MD · Internal medicine & clinical pharmacology
Letters about OP-05 usually want an 800 mg tablet to behave like a first-night sleeping pill. It will not. I answer as I would on a lilac ward-round: stairs, creatinine, taper, opioids, labeled rooms. Teaching, not your prescription.
Because 800 mg is a later labeled tablet, not night one. Adult PHN starts at 300 mg once, then 600 mg on day two, 900 mg on day three. Epilepsy from age twelve starts at 300 mg three times daily. Pharmacies stock 800s because later totals need them. Starting there is how dizziness and somnolence arrive before any pain benefit. Ask for 300 mg capsules if that is the step you are actually on.
What an 800 mg Neurontin later rung costs after titration - can you quote Dublin?
I will not invent a euro price for a clinic that does not fill. The strip on the card shows four licensed US windows quoting an 800 mg by ninety generic count - grocery and mail desks, each link that chain only. Coupon prints move by ZIP. Cost after titration means you already live on a later total. If you are still on night-one 300s, you are asking the wrong question of an 800 mg blister.
My eGFR is 38. Can I still take an 800 mg tablet twice a day?
Creatinine clearance between 30 and 59 mL/min puts the whole day in the 400-1400 mg band, twice daily. Two 800 mg tablets would be 1600 mg, which overshoots that band. One 800 mg once daily might sit inside it, or a smaller twice-daily pair might fit better. I need the actual Cockcroft-Gault number and the indication, and I am not your prescriber. The point: kidneys rewrite the 800, they do not decorate it.
I stopped last Tuesday because I felt better. Now I feel awful. Coincidence?
Unlikely. The label wants at least a one-week down-ramp when you reduce, stop, or swap, and longer if the chart is fragile. Abrupt stops have been tied to more seizures, withdrawal symptoms, and suicidal thinking. Even without epilepsy, people report a rebound week. Restarting or tapering is a clinician job, not a forum taper. Tell them you slammed the door so they do not treat the rebound as a new disease.
I take oxycodone at night. Is the 800 mg evening tablet a problem?
It can be. Gabapentin plus opioids can cause life-threatening respiratory depression. Oxycodone is named. Older age and COPD make it worse. Morphine raised gabapentin AUC about 44 percent in interaction work, which is a reminder that the pair is not just 'two drowsy things.' If a prescriber still uses both, they should start gabapentin low and someone at home should know what slow breathing looks like. Do not add the 800 yourself because pain broke through.
Can I use it as my sleeping tablet instead of zopiclone?
Somnolence is an adverse reaction, not an indication. PHN trials saw it in 21 percent versus 5 percent on placebo. Using an 800 mg later rung as a hypnotic is how people fall in the night and then ask for more because sleep 'needs a boost.' If insomnia is the problem, say so. I will not dress Neurontin up as a cleaner zopiclone on a pastel card.
The GP wrote it for my diabetic feet. Is that on the Neurontin stamp?
The US Neurontin stamp is adult postherpetic neuralgia and adjunctive partial-onset seizures from age three. Diabetic nerve pain is a hallway clinics walk every day, and some trials exist, but it is not this licence. That does not make your GP reckless by itself. It does mean you should hear it as off-label, with the same renal, taper, and opioid rules. The evidence study is the longer hallway.
I split the 800 mg scored tablet. How long can I keep the other half?
Twenty-eight days, then bin it. The unused half is meant to be the next dose, not a jewellery-box stash. Capsules should be swallowed whole. Food is fine. If you need 400 mg steps, a 400 mg capsule is cleaner than a crumbling 800. Scored tablets exist so later totals can be held, not so night one becomes a DIY 400.
Why three times a day if the half-life is only six hours?
Because the half-life is 5 to 7 hours in working kidneys, and the label will not let gaps exceed twelve hours. A once-daily 800 would leave a long trough for a drug that is not a controlled-release Neurontin. Gralise is the once-daily PHN product, and it is not interchangeable milligram for milligram. Three swallows is how this immediate-release card stays in range. Kidneys that are failing change the rhythm - that is the other table.
Maalox sits next to my bed. Does it matter?
Aluminium-magnesium antacid cut mean gabapentin bioavailability about 20 percent. Waiting two hours after the antacid made the hit about 10 percent. I would separate them rather than 'just take everything at lights-out.' Food itself only bumps AUC about 14 percent, so dinner is not the villain. The antacid is the quiet thief.
My father got unsteady and his ankles puffed. Is that the 800?
Dizziness, somnolence, ataxia, and peripheral edema are the everyday cluster, worse when someone climbs too fast or sits on a later rung with older kidneys. PHN trials put dizziness at 28 percent versus 8 percent on placebo. Unsteadiness in an older man is a fall until proven otherwise. I would look at creatinine, the climb speed, and any oxycodone before I called it 'just getting used to it.'
Is this the same as Lyrica or the restless-legs tablet I saw advertised?
Pregabalin is a cousin, not this tablet. Gabapentin enacarbil (Horizant) is a prodrug with its own restless-legs and PHN stamps. Gralise is a once-daily gabapentin for PHN that you must not swap one-for-one with Neurontin. An 800 mg Neurontin tablet is immediate-release gabapentin on a later rung. Names get sloppy in reviews. The objects do not.
I take Stromectol once a year on a travel clinic plan. Any clash?
No meaningful CYP clash sits on these two cards. Ivermectin is a one-day fasted antiparasitic cleared in stool. Gabapentin is a renal, three-times-daily later-rung pain or seizure tablet. The only shared sentence is honesty with the prescriber who owns each chart. Do not skip your Neurontin the morning you take Stromectol unless that clinician said to, and do not treat either as a cart from this Dublin floor.
Read these as teaching on a general point, not as a care plan for whoever asked. Anything specific to you belongs with a prescriber who can see your notes, bloods and full medicine list at once.