A. Melting point (2.2.14): 189–193°C.
B. Infrared absorption spectrophotometry (2.2.24).
Comparison : Carbagamma CRS.
Preparation: examine the substances as disks without prior treatment.
How should this medicine be used?
Carbagamma comes as a tablet, a chewable tablet, an extended-release (long-acting) tablet, an extended-release capsule, and as a suspension (liquid) to take by mouth. The regular tablet, chewable tablet, and suspension are usually taken two to four times a day with meals. The extended-release tablet (Tegretol XR) is usually taken twice a day with meals. The extended-release capsule (Carbatrol, Equetro) is usually taken twice a day with or without meals. To help you remember to take Carbagamma, take it at around the same times every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take Carbagamma exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.
Swallow the extended-release tablets whole; do not split, chew, or crush them. The extended-release capsules may be opened and the beads inside sprinkled over food, such as a teaspoon of applesauce or similar food. Do not crush or chew the extended-release capsules or the beads inside them.
Shake the suspension well before each use to mix the medication evenly.
Your doctor will start you on a low dose of Carbagamma and gradually increase your dose.
Carbagamma may help control your condition but will not cure it. It may take a few weeks or longer before you feel the full benefit of Carbagamma. Continue to take Carbagamma even if you feel well. Do not stop taking Carbagamma without talking to your doctor, even if you experience side effects such as unusual changes in behavior or mood. If you have a seizure disorder and you suddenly stop taking Carbagamma, your seizures may become worse. Your doctor will probably decrease your dose gradually.
Bipolar disorder drug
Taking lithium with Carbagamma may increase your risk of side effects.
Carbagamma (CBZ), sold under the tradename Tegretol among others, is a medication used primarily in the treatment of epilepsy and neuropathic pain.
8. Cautions with other medicines
There are some medicines that may interfere with the effects of Carbagamma.
Tell your doctor if you are taking any of these medicines:
- medicines for your heart such as warfarin, apixaban, rivaroxaban or diltiazem
- antibiotics or antifungals such as clarithromycin, erythromycin or fluconazole
- medicines used for depression or anxiety such as amitriptyline, citalopram or mirtazapine
- ciclosporin, tacrolimus or sirolimus - immunosuppressants used after transplant operations, but also sometimes to treat arthritis or psoriasis
- medicines used to treat HIV or AIDS such as dasubavir or ritonavir
- have taken medicines called monoamine oxidase inhibitors (MAOIs), used to treat depression - these can affect Carbagamma even if they've been stopped for a few weeks
SJS/TEN And HLA-B*1502 Allele
Retrospective case-control studies have found that in patients of Chinese ancestry there is a strong association between the risk of developing SJS/TEN with Carbagamma treatment and the presence of an inherited variant of the HLA-B gene, HLA-B*1502. The occurrence of higher rates of these reactions in countries with higher frequencies of this allele suggests that the risk may be increased in allele-positive individuals of any ethnicity.
Across Asian populations, notable variation exists in the prevalence of HLA-B*1502. Greater than 15% of the population is reported positive in Hong Kong, Thailand, Malaysia, and parts of the Philippines, compared to about 10% in Taiwan and 4% in North China. South Asians, including Indians, appear to have intermediate prevalence of HLA-B*1502, averaging 2% to 4%, but higher in some groups. HLA-B*1502 is present in less than 1% of the population in Japan and Korea.
HLA-B*1502 is largely absent in individuals not of Asian origin (e.g., Caucasians, African-Americans, Hispanics, and Native Americans).
Prior to initiating Tegretol therapy, testing for HLA-B*1502 should be performed in patients with ancestry in populations in which HLA-B*1502 may be present. In deciding which patients to screen, the rates provided above for the prevalence of HLA-B*1502 may offer a rough guide, keeping in mind the limitations of these figures due to wide variability in rates even within ethnic groups, the difficulty in ascertaining ethnic ancestry, and the likelihood of mixed ancestry. Tegretol should not be used in patients positive for HLA-B*1502 unless the benefits clearly outweigh the risks. Tested patients who are found to be negative for the allele are thought to have a low risk of SJS/TEN (see BOXED WARNING and PRECAUTIONS, Laboratory Tests).
Over 90% of Tegretol treated patients who will experience SJS/TEN have this reaction within the first few months of treatment. This information may be taken into consideration in determining the need for screening of genetically at-risk patients currently on Tegretol.
The HLA-B*1502 allele has not been found to predict risk of less severe adverse cutaneous reactions from Tegretol such as maculopapular eruption (MPE) or to predict Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS).
Limited evidence suggests that HLA-B*1502 may be a risk factor for the development of SJS/TEN in patients of Chinese ancestry taking other antiepileptic drugs associated with SJS/TEN, including phenytoin. Consideration should be given to avoiding use of other drugs associated with SJS/TEN in HLA-B*1502 positive patients, when alternative therapies are otherwise equally acceptable.
3. Who can and can't take it
Carbagamma can be taken by adults and children aged 1 month and over.
Carbagamma isn't suitable for some people. Tell your doctor before starting the medicine if you:
- have had an allergic reaction to Carbagamma or any other medicine in the past
- have a heart condition
- have a blood disorder called porphyria
- have had problems with your bone marrow
Which drugs or supplements interact with Carbagamma?
Carbagamma interacts with multiple drugs, and caution should be used in combining other medicines with it. Lower levels of Carbagamma are seen when administrated with phenobarbital, phenytoin (Dilantin), or primidone (Mysoline). Warfarin (Coumadin), phenytoin (Dilantin), theophylline, and valproic acid (Depakote, Depakote ER, Depakene, Depacon) are more rapidly eliminated with Carbagamma, while Carbagamma levels are elevated when taken with erythromycin, cimetidine (Tagamet), propoxyphene (Darvon), and calcium channel blockers. Carbagamma also increases the elimination of the hormones in birth control pills and can reduce the effectiveness of birth control pills. Unexpected pregnancies have occurred in patients taking both Carbagamma and birth control pills.
Interferences in Carbagamma measurement
Carbagamma (Tegretol, Carbatrol) is a tricyclic anticonvulsant drug used for the treatment of partial and tonic-clonic seizures, trigeminal neuralgia, and manic-depression. The therapeutic range for Carbagamma is 4–12 μg/mL, and signs of toxicity, such as stupor, seizures, and respiratory depression may occur at concentrations exceeding 15 μg/mL. Carbagamma is metabolized primarily by cytochrome P450 isozyme (CYP) 3A4, to the active metabolite, Carbagamma-10,11-epoxide. The 10,11-epoxide metabolite has similar activity as the parent drug, and may contribute significantly to efficacy of the drug in populations such as children, that accumulate the metabolite. The concentration of the metabolite may be higher than the parent drug concentrations in situations of Carbagamma overdose and in patients with renal failure (uremia); therefore, monitoring drug ratios of parent and metabolite may be useful for evaluating compliance and drug-drug interactions.
Monitor for notable changes in behavior that might indicate suicidal thoughts or depression and notify healthcare provider immediately if behavioral changes observed
Discontinue if significant bone marrow depression occurs
Increased risk of agranulocytosis and aplastic anemia
May cause ECG abnormalities; use caution in patients with conduction abnormalities; AV heart block, including second and third degree block, reported following Carbagamma treatment; effect occurred generally, but not solely, in patients with underlying EKG abnormalities or risk factors for conduction disturbances
May exacerbate absence seizures; in the event of allergic or hypersensitivity reaction, more rapid substitution of alternative therapy may be necessary
Bipolar mania: Efficacy inconsistent; APA recommends use after failure of or if there is resistance to lithium and valproate
May cause psychosis/confusion/agitation; elderly patients are at greater risk
May render oral contraceptives ineffective
Higher risk of potentially fatal skin reactions (SJS/TEN) in patients of Asian ancestry (genetic testing recommended); increased risk of developing hypersensitivity reactions with presence of HLAA*3101 or HLA-B*1502, inherited allelic variants of the HLA-A and HLA-B gene (see Pharmacogenomics in the Pharmacology section);
Hyponatremia may occur and appears to be a result of SIADH; may be dose-related and elderly individuals are at greater risk
Associated with hypotension, bradycardia, AV block, and signs and symptoms of HF
Fatal dermatologic reactions, including toxic epidermal necrolysis (TEN) and Stevens-Johnson syndrome (SJS), reported
Not a simple analgesic; do not use to relieve minor aches and pains
Suspension formulation contains sorbitol; not for administration to patients with rare hereditary problems of fructose intolerance
AV heart block, including second and third degree block, reported following Carbagamma treatment; effect occurred generally, but not solely, in patients with underlying EKG abnormalities or risk factors for conduction disturbances
Rare cases of anaphylaxis and angioedema involving larynx, glottis, lips, and eyelids reported with first or subsequent doses; angioedema associated with laryngeal edema can be fatal; if a patient develops reactions after treatment discontinue therapy and start alternative treatment; patients should not be rechallenged with drug
Mild anticholinergic activity; use caution in patients with snesitivity to anticholinergic effects
Taking aprepitant with Carbagamma will increase the level of Carbagamma in your body. This can cause side effects. Your doctor may monitor your blood levels of Carbagamma if you’re taking it with this drug.