Carbamazepine properties

Other agents are also used for the treatment of manic-depressive disorders based on preliminary clinical results (177). The antiepileptic carbamazepine [298-46-4] has been reported in some clinical studies to be therapeutically beneficial in mild-to-moderate manic depression. Carbamazepine treatment is used especially in bipolar patients intolerant to lithium or nonresponders. A majority of Hthium-resistant, rapidly cycling manic-depressive patients were reported in one study to improve on carbamazepine (178). Carbamazepine blocks noradrenaline reuptake and inhibits noradrenaline exocytosis. The main adverse events are those found commonly with antiepileptics, ie, vigilance problems, nystagmus, ataxia, and anemia, in addition to nausea, diarrhea, or constipation. Carbamazepine can be used in combination with lithium. Several clinical studies report that the calcium channel blocker verapamil [52-53-9] registered for angina pectoris and supraventricular arrhythmias, may also be effective in the treatment of acute mania. Its use as a mood stabilizer may be unrelated to its calcium-blocking properties. Verapamil also decreases the activity of several neurotransmitters. Severe manic depression is often treated with antipsychotics or benzodiazepine anxiolytics. 

The phenomenon of pseudopolymorphism is also observed, i.e., compounds can crystallize with one or more molecules of solvent in the crystal lattice. Conversion from solvated to nonsolvated, or hydrate to anhydrous, and vice versa, can lead to changes in solid-state properties. For example, a moisture-mediated phase transformation of carbamazepine to the dihydrate has been reported to be responsible for whisker growth on the surface of tablets. The effect can be retarded by the inclusion of Polyoxamer 184 in the tablet formulation [61]. 

Neutral molecules show a range of retention properties between those of acids and bases. Progesterone membrane retention is very high in all cases. Griseofulvin and carbamazepine retention steeply increase with phospholipid content. The patterns of retention follow the lipophilicity properties of the molecules, as indicated by octanol-water apparent partition coefficients (Table 7.4). 

From the examination of structure-activity relationships, it has been concluded that a phenyl moiety at C-6 as well as a 4-hydroxypiperidine side-chain attached to C-3 of the pyridazine system is essential for anticonvulsant activity in this class of compounds [184], Compounds (54) and (55) have been found to have similar anticonvulsant profiles in animals (mice, rats and baboons) [165, and literature cited therein] and to represent potent broad-spectrum antiepileptic drugs. Their potency with regard to antagonizing seizures (induced by electro-shock or various chemicals) has been compared with standard anticonvulsants like carbamazepine and phenobarbitone [185, 186], A quantitative electroencephalographic analysis of (55) has been published [187]. From in vitro studies it has been concluded that the anticonvulsant activities of these compounds are not mediated by an enhancement of GABAergic transmission or by an interaction with benzodiazepine receptor sites [ 165,186,187], On the other hand, in vivo experiments showed that (54), at anticonvulsant doses, increases the affinity of flunitrazepam for its central receptor site [ 186], Investigations of (54) and (55) in a behavioural test predictive of antianxiety activity revealed a marked difference in the pharmacological profiles of these structurally closely related compounds the dichloro compound SR 41378 (55) has also been found to possess anxiolytic (anticonflict) properties [165],... 

The mechanism of action of carbamazepine is complex, and is complicated by the fact that it has a long half-life metabolite, carbamazepine epoxide, which also has pronounced psychotropic properties. 

Q61 Carbamazepine has anti-epileptic and psychotropic properties. Carbamazepine is related chemically to the tricyclic antidepressants. 

Carbamazepine is an anti-epileptic with psychotropic properties. It is chemically related to tricyclic antidepressants. Its uses include the treatment of... 

Oxcarbazepine is a derivative of carbamazepine and although its precise mechanism of action is unknown it has similar properties as carbamazepine and is also used for the treatment of primary generalized tonic-clonic seizures and partial seizures. Also the adverse effects are similar to those of carbamazepine. However the drug interaction profile is different as oxcarbazepine has hardly any enzyme-inducing capacity. 

Oxcarbazepine is chemically and pharmacologically closely related to carbamazepine, but it has much less capacity to induce drug-metabolizing enzymes. This property decreases the problems associated with drug interactions when oxcarbazepine is used in combination with other drugs. The clinical uses and adverse effect profile of oxcarbazepine appear to be similar to those of carbamazepine. 

Several anticonvulsant medications have mood-stabilizing properties. Valproic acid and carbamazepine are... 

HT2, and receptors and possesses very little extrapyramidal toxicity but significant sedative and autonomic side effects. Flumazenil is a benzodiazepine antagonist, and carbamazepine is an anticonvulsant neither possesses significant antipsychotic properties. 

In the Expert Consensus survey (Rush and Frances, 2000), respondents were asked to rate which classes of medication may be helpful for treating patients with severe and persistent physical aggression and those who destroyed property. The atypical antipsychotics were rated most highly, followed by anticonvulsant/ mood stabilizer. These were followed (with much lower priority) by antidepressants and beta-blockers. Among the atypical antipsychotics, risperidone was rated most highly, followed by olanzapine others had much lower ratings. Divalproex or valproic acid and carbamazepine were rated highest of the mood stabi-... 

Carbamazepine produces complex effects in a variety of neurotransmitters, receptors, and second messenger and neuropeptide systems (Post et al. 1992, 1994a). Determining which of these effects is most closely associated with its psychotropic properties in bipolar disorder and which of these or other effects may be responsible for the augmentation response in combination therapy with dihydropyridine L-type CCBs remains to be further evaluated. However, discussion of two possibilities might be beneficial. One possibility, of course, is that actions of carbamazepine unrelated to calcium dynamics account for its augmenting effects with nimodipine. The plethora of these other... 

Moller HJ, Kissling W, Riehl T, et al Double blind evaluation of the antimanic properties of carbamazepine as a comedication to haloperidol. Prog Neuropsycho-pharmacol Biol Psychiatry 13 127-136, 1989... 

Oxcarbazepine is a keto derivative of carbamazepine but offers several advantages over carbamazepine. Oxcarbazepine does not require blood cell count, hepatic, or serum drug level monitoring. It causes less cytochrome P450 enzyme induction than does carbamazepine (but may decrease effectiveness of oral contraceptives containing ethinyl estradiol and levonorgestrel). As opposed to carbamazepine, oxcarbazepine does not induce its own metabolism. These properties, combined with its similarity to carbamazepine, led many clinicians to use this medication for the treatment of bipolar disorder. Randomized controlled trials suggested efficacy in the treatment of acute mania compared with lithium and haloperidol, but these trials were quite small and did not include a placebo control (Emrich 1990). 

Other agents with anticonvulsant properties that may be of use m the treatment of bipolar disorder include topiramate, gabapentin, tiagabine and carbamazepine (Janicak et al., 2001). 

Limited evidence indicates that carbamazepine plus an antipsychotic may also benefit some schizophrenic patients. This is an interesting possibility in view of the similar antimanic properties of lithium and carbamazepine (375). This area requires further research, especially to clarify the indications for combining anticonvulsants with an antipsychotic. For example, mania complicated by psychotic features may benefit from lithium, valproate, or carbamazepine augmented by antipsychotics. Because carbamazepine induces the metabolism of at least some antipsychotics (e.g., haloperidol, thiothixene), dose adjustment based on TDM may be necessary to achieve the optimal effect. 

Other than slow taper, no consistently effective treatment to alleviate withdrawal symptoms has been reported. Although several compounds have been studied (e.g., b-blockers, clonidine, carbamazepine, abercamil, ondansetron), results have been contradictory ( 250). Carbamazepine, however, may be useful in seizure-prone patients (251). Valproate (VPA) has also been reported to benefit patients undergoing BZD discontinuation after long-term dependence ( 252), which may be related to VPA s potential anxiolytic properties, its ability to alleviate withdrawal phenomena, or both. The azaspirone anxiolytic buspirone has been reported ineffective in suppressing withdrawal symptoms, particularly in long-term BZD users (253, 254). Hydroxyzine has also been found beneficial in treating patients for lorazepam withdrawal (255). 

If these measures fail, clonidine, fluphenazine, clonazepam, or carbamazepine should be tried. The pharmacologic properties of these drugs are discussed elsewhere in this book. Clonidine reduces motor or vocal tics in about 50% of children so treated. It may act by reducing activity in noradrenergic neurons in the locus coeruleus. It is introduced at a dose of 2-3 mcg/kg/d, increasing after 2 weeks to 4 mcg/kg/d and then, if required, to 5 mcg/kg/d. It may cause an initial transient fall in blood pressure. The most common adverse effect is sedation other adverse effects include reduced or excessive salivation and diarrhea. Phenothiazines such as fluphenazine sometimes help the tics, as do dopamine... 

In 1962, Blom was the first to report the analgesic properties of carbamazepine in neuropathic pain conditions. In clinical studies in patients suffering from trigeminal neuralgia, oral doses of up to 2400 mg/day for 5 to 14 days produced moderate to excellent results (Campbell et al., 1966 Killian and Fromm, 1968 Nicol,... 

Otsuka, M. Hasegawa, H. Matsuda, Y., Effect of polymorphic transformation during the extrusion-granulation process on the pharmaceutical properties of carbamazepine granules Chem. Pharm. Bull. 1997, 45, 894-898. 

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