Structure of carbamazepine: 5H-dibenz[b,f]azepine-5-carboxamide

Himes, V. L.; Mighell, A. D.; Camp, Wilson H. De

doi:10.1107/s0567740881008522

Cited by 96 publications

(58 citation statements)

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“…DSC is usually combined with XRPD to determine the polymorphic composition of pharmaceutical powders, when the polymorphs present have different melting points. DSC thermograms of carbamazepine polymorph form I show no transformation and melts between 189 and 193 • C (Himes et al, 1981). Form II does not melt, but instead a transformation occurs between 135 and 170 • C and the new phase then melts between 188 and 192 • C. The large transformation range is due, in part, to higher initiation temperatures for crystals with fewer defects as determined by observing populations of crystals during heating.…”

Section: Solid State Characterization Of Carbamazepine In Liquisolid mentioning

confidence: 97%

“…Form III melts and crystallizes to a new form nearly simultaneously between 162 and 175 • C. The new form subsequently melts between 189 and 193 • C. Form IV shows melting and partial crystallization to a new form between 178 and 187 • C, significantly higher than the transition temperatures of forms II or III. This is followed by further crystallization to produce a material that then melts between 190 and 192 • C. Based on the melting point of the form that is derived from the others upon heating, it appeared that each had become form I (Himes et al, 1981).…”

Section: Solid State Characterization Of Carbamazepine In Liquisolid mentioning

confidence: 99%

“…Therefore, it is important to study the polymorphic changes of carbamazepine in liquisolid formulations. Carbamazepine has been found to crystallize as four different anhydrous polymorphs (Himes et al, 1981;Lowes et al, 1987;Ceolin et al, 1997;Nokhodchi et al, 2005a;Bolourtchian et al, 2001). The most reliable way to distinguish between the four polymorphs of CBZ is with PXRD.…”

Section: Solid State Characterization Of Carbamazepine In Liquisolid mentioning

confidence: 99%

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Liquisolid technique for dissolution rate enhancement of a high dose water-insoluble drug (carbamazepine)

Javadzadeh

Jafari-Navimipour

Nokhodchi

2007

International Journal of Pharmaceutics

178

135

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Different liquisolid formulations of carbamazepine were accomplished by dissolving the drug in the non-toxic hydrophilic liquids, and adsorbing the solution onto the surface of silica. In order to reduce the amounts of carrier and aerosil in liquisolid formulations, some additives namely polyvinylpyrrolidone (PVP), hydroxypropyle methylcellulose (HPMC) and polyethylene glycol (PEG 35000) were added to liquid medication to increase loading factor. The effects of various ratios of carrier to coating material, PVP concentration, effect of aging and type of the carrier on dissolution rate of liquisolid compacts were studied. X-ray crystallography and differential scanning calorimetery (DSC) were used for evaluation of physicochemical properties of carbamazepine in liquisolid formulations. The results showed that the drug loading factor was increased significantly in the presence of additives. Liquisolid formulations containing PVP as additive, exhibited significantly higher drug dissolution rates compared to the compacts prepared by the direct compression technique. It was shown that microcrystalline cellulose had more liquid retention potential in comparison with lactose, and the formulations containing microcrystalline cellulose as carrier, showed higher dissolution rate. By decreasing the ratio of microcrystalline cellulose to silica from 20 to 10, an improvement in dissolution rate was observed. Further decrease in the ratio of microcrystalline cellulose:silica from 10 to 5 resulted in a significant reduction in dissolution rate. Increasing of PVP concentration in liquid medication caused a dramatic increase in dissolution rate at first 30 min. The results showed that the dissolution rate of liquisolid tablets was not significantly affected by storing the tablets at 25• C/75% relative humidity for a period of 6 months. The results of DSC and X-ray crystallography did not show any changes in crystallinity of the drug and interaction between carbamazepine and exipients during the process.

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Section: Solid State Characterization Of Carbamazepine In Liquisolid mentioning

confidence: 97%

Section: Solid State Characterization Of Carbamazepine In Liquisolid mentioning

confidence: 99%

Section: Solid State Characterization Of Carbamazepine In Liquisolid mentioning

confidence: 99%

See 1 more Smart Citation

Liquisolid technique for dissolution rate enhancement of a high dose water-insoluble drug (carbamazepine)

Javadzadeh

Jafari-Navimipour

Nokhodchi

2007

International Journal of Pharmaceutics

178

135

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“…Different polymorphic forms were described [79][80][81][82][83][84][85][86][87][88][89][90][91]. Four anhydrous polymorphs were characterized: I, II, III, and IV, respectively identified as triclinic, trigonal, monoclinic, and monoclinic [77].…”

Section: Carbamazepinementioning

confidence: 99%

“…Highly different polymorphic forms of carbamazepine, a drug used in the treatment of epilepsy and trigeminal neuralgia, were discovered through classical crystallization methods and fully characterized from a physicochemical point of view [79][80][81][82][83][84][85][86][87][88][89]. More recently, a crystal engineering design strategy has facilitated supramolecular synthesis of 13 new crystalline phases of carbamazepine [90].…”

Section: Carbamazepinementioning

confidence: 99%

Polymorph Impact on the Bioavailability and Stability of Poorly Soluble Drugs

2015

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Drugs with low water solubility are predisposed to poor and variable oral bioavailability and, therefore, to variability in clinical response, that might be overcome through an appropriate formulation of the drug. Polymorphs (anhydrous and solvate/hydrate forms) may resolve these bioavailability problems, but they can be a challenge to ensure physicochemical stability for the entire shelf life of the drug product. Since clinical failures of polymorph drugs have not been uncommon, and some of them have been entirely unexpected, the Food and Drug Administration (FDA) and the International Conference on Harmonization (ICH) has required preliminary and exhaustive screening studies to identify and characterize all the polymorph crystal forms for each drug. In the past, the polymorphism of many drugs was detected fortuitously or through manual time consuming methods; today, drug crystal engineering, in particular, combinatorial chemistry and high-throughput screening, makes it possible to easily and exhaustively identify stable polymorphic and/or hydrate/dehydrate forms of poorly soluble drugs, in order to overcome bioavailability related problems or clinical failures. This review describes the concepts involved, provides examples of drugs characterized by poor solubility for which polymorphism has proven important, outlines the state-of-the-art technologies and discusses the pertinent regulations.

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Polymorphs

2017

Solid State Properties of Pharmaceutical Materials

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Structure of carbamazepine: 5H-dibenz[b,f]azepine-5-carboxamide

Cited by 96 publications

References 1 publication

Liquisolid technique for dissolution rate enhancement of a high dose water-insoluble drug (carbamazepine)

Liquisolid technique for dissolution rate enhancement of a high dose water-insoluble drug (carbamazepine)

Polymorph Impact on the Bioavailability and Stability of Poorly Soluble Drugs

Polymorphs

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