The SG 180 imprint identifies a prescription capsule containing Gabapentin 300 mg, manufactured by ScieGen Pharmaceuticals, Inc. Belonging to the class of medications known as gabapentinoids, gabapentin is widely prescribed to manage neuropathic pain and control specific types of epileptic seizures.
Physical Identification
Physical Parameter Specification
- Active Ingredient – Gabapentin (300 mg)
- Form – Hard gelatin capsule
- Color – Yellow cap and yellow body (opaque)
- Imprint – SG on the cap, 180 on the body (in black ink)
- Manufacturer -ScieGen Pharmaceuticals, Inc.
- Drug Class – Anticonvulsant / Gabapentinoid
- If you possess a pill with a different color, shape, or imprint, do not assume it is gabapentin. Consult a pharmacist for verification.
Mechanism of Action
Despite its chemical structural similarity to gamma-aminobutyric acid , gabapentin does not bind directly to receptors, nor does it alter uptake or degradation.
Instead, its therapeutic mechanism works through the following pathways:
- High-Affinity Binding: Gabapentin selectively binds to the alpha auxiliary subunits of voltage-gated calcium channels (VGCCs) located within the central nervous system.
- Inhibition of Calcium Influx: By binding to these subunits, gabapentin reduces the presynaptic trafficking of calcium channels and attenuates calcium influx in hyperexcitable neurons.
- Reduction of Neurotransmitter Release: This decrease in calcium movement diminishes the release of excitatory neurotransmitters (such as glutamate, substance P, and norepinephrine), effectively suppressing hyper-stimulated pain signals and stabilizing chaotic electrical discharge in brain circuits.
Approved Indications & Usage
Gabapentin 300 mg is FDA-approved for two main clinical uses:
- Postherpetic Neuralgia (PHN): Management of chronic nerve pain resulting from shingles (varicella-zoster infection) in adults.
- Partial-Onset Seizures: Adjunctive therapy (used alongside other anti-seizure medications) in treating partial-onset seizures with or without secondary generalization in adults and pediatric patients aged 3 years and older.
Off-Label Uses
Healthcare providers frequently prescribe gabapentin off-label for conditions such as diabetic peripheral neuropathy, restless legs syndrome (RLS), fibromyalgia, generalized anxiety disorder, and alcohol withdrawal syndrome.
Dosage Guidance
Dosing of Gabapentin 300 mg varies based on the condition being treated, patient age, and kidney function.
- Important: Doses must be individualized by a licensed physician. Never adjust or stop your prescribed dose without medical guidance.
Postherpetic Neuralgia (Adults)
To minimize initial side effects like drowsiness and dizziness, gabapentin is typically titrated over 3 days:
- Day 1: Single 300 mg dose at bedtime.
- Day 2: 300 mg twice daily (600 mg total).
- Day 3: 300 mg three times daily (900 mg total).
- Maintenance: Titrated as needed up to a maximum recommended dose of 1,800 mg per day (600 mg 3 times daily).
Epilepsy / Partial Seizures (Adults & Children >12 Years)
- Starting Dose: 300 mg taken 3 times daily.
- Maintenance Range: 900 mg to 2,400 mg daily divided into three equal doses.
- Maximum Dose: Up to 3,600 mg daily.
- Timing Constraint: The time interval between any two doses should not exceed 12 hours to maintain consistent plasma concentrations and prevent breakthrough seizures.
Dosage Adjustments in Renal Impairment
Because gabapentin is cleared almost entirely unchanged via renal excretion, dosage reductions are necessary for patients with reduced kidney function (creatinine clearance) or those undergoing hemodialysis.
Side Effects
Common Side Effects
Most side effects are mild-to-moderate and tend to diminish as the body adjusts to the medication:
- Central Nervous System: Drowsiness (somnolence), dizziness, lightheadedness, and fatigue.
- Motor Control: Unsteadiness, clumsiness, or poor coordination (ataxia).
- Fluid Retention: Swelling in the lower legs, feet, or hands (peripheral edema).
- Gastrointestinal: Nausea, vomiting, or dry mouth.
- Pediatric-Specific: Children (ages 3–12) may exhibit emotional lability, hostility, hyperactivity, or difficulty concentrating.
Serious Adverse Reactions
Contact emergency services or seek immediate medical care if you experience:
- DRESS Syndrome: Drug Reaction with Eosinophilia and Systemic Symptoms, a severe multiorgan reaction characterized by fever, rash, swollen lymph nodes, and liver/kidney inflammation.
- Severe Allergic Reactions (Anaphylaxis/Angioedema): Swelling of the face, lips, tongue, or throat causing difficulty breathing or swallowing.
- Severe Respiratory Depression: Abnormally slow, shallow, or labored breathing.
Precautions & Warnings
CNS Depression & Impairment
Gabapentin causes significant central nervous system depression. Do not drive, operate heavy machinery, or perform hazardous tasks until you fully understand how the medication affects your alertness and reaction times.
Respiratory Depression
There is a heightened risk of life-threatening respiratory depression when gabapentin is co-administered with:
- Opioid analgesics (e.g., morphine, oxycodone, fentanyl).
- Central nervous system depressants (e.g., benzodiazepines, muscle relaxants, alcohol).
- Pre-existing respiratory disorders such as Chronic Obstructive Pulmonary Disease (COPD) or asthma.
Suicidal Ideation and Behavior
Like all antiepileptic drugs (AEDs), gabapentin increases the risk of suicidal thoughts or behaviors in a small proportion of patients . Patients and caregivers should monitor closely for sudden changes in mood, worsening depression, or agitation.
Withdrawal Risk (Avoid Sudden Discontinuation)
Abruptly stopping gabapentin can trigger withdrawal symptoms, including anxiety, insomnia, sweating, nausea, and pain. In patients taking gabapentin for epilepsy, sudden discontinuation can precipitate status epilepticus or severe rebound seizures. Discontinuation should always occur through a gradual dose taper over at least 1 week under medical supervision.
Key Drug Interactions
- Opioids: Concomitant use increases gabapentin concentrations, leading to profound sedation and respiratory depression.
- Antacids (Aluminum/Magnesium Hydroxide): Antacids can decrease gabapentin absorption by approximately 20%. Take gabapentin at least 2 hours after taking an antacid.
- Alcohol: Potentiates the sedative and dizzying effects of gabapentin.