Relevance of pH Dependency on in Vitro Release of Bromocriptine from a Modified-Release Formulation

Drewe, Jürgen; Keck, Martin E.; Guitard, P; Pellet, Andre; Johnston, Britton; Beglinger, Christoph

doi:10.1002/jps.2600800215

Cited by 8 publications

(4 citation statements)

References 12 publications

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“…The effect of the SOR on the dissolution profile of OXA was observed most greatly in the buffer with a pH similar to pKa (6.88). Drewe et al . (1991) reported that the dissolution profiles of a water‐soluble drug with low solubility was greatly dependant on the pH of the test medium related to the pKa of the drug, however, this pH dependency of the in vitro release did not result in a loss in the extent of bioavailability.…”

Section: Discussionmentioning

confidence: 99%

“…The effect of the SOR on the dissolution pro®le of OXA was observed most greatly in the buffer with a pH similar to pKa (6.88). Drewe et al (1991) reported that the dissolution pro®les of a water-soluble drug with low solubility was greatly dependant on the pH of the test medium related to the pKa of the drug, however, this pH dependency of the in vitro release did not result in a loss in the extent of bioavailability. The results of our study support those of the report written by Drewe et al (1991), and we concluded that the dissolution behaviour of a hydrophobic drug such as OXA is highly dependant on the pH of the buffer used for the dissolution test.…”

Section: Discussionmentioning

confidence: 99%

“…Drewe et al (1991) reported that the dissolution pro®les of a water-soluble drug with low solubility was greatly dependant on the pH of the test medium related to the pKa of the drug, however, this pH dependency of the in vitro release did not result in a loss in the extent of bioavailability. The results of our study support those of the report written by Drewe et al (1991), and we concluded that the dissolution behaviour of a hydrophobic drug such as OXA is highly dependant on the pH of the buffer used for the dissolution test. A pH of proventriculus in 17 h fasting was reported to be 3.77 (Winget et al, 1962) and that in feeding was reported 2.25 (Relay & Austic, 1984) and 4.4 (Otani, 1969).…”

Section: Discussionmentioning

confidence: 99%

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The effect of soybean oil refuse powder used as vehicle on the absorption of oxolinic acid in chickens under fasting and nonfasting conditions and the correlation with in vitro dissolution

Hamamoto

Koike

Machida

2001

Vet Pharm & Therapeutics

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The effect of soybean oil refuse powder (SOR) when used as a vehicle on the absorption of oxolinic acid (OXA) powder in chicken, the dissolution profile of OXA and the correlation between in vivo and in vitro study were examined. To examine in vivo bioavailability, chickens fed or fasted were studied using a 2 x 2 crossover design. The OXA was administered OXA or OXA-SOR (1 : 9) mixture 20 mg OXA/kg. In vitro dissolution rates for OXA and OXA-SOR were measured using the paddle (PD) and the rotatory dialysis cell dissolution (PTSW) methods. Maximum plasma concentration (Cmax) and area under the curve (AUC) were significantly increased by the addition of SOR to OXA. Differences between OXA and OXA-SOR were more remarkable under fasted as compared with fed condition. In vitro dissolution rates of OXA-SOR pH 1.2, 6.5 and 7.2 as determined by the PD and the PTSW methods were increased in the presence of SOR vehicle. Differences between OXA and OXA-SOR in vitro dissolution rates were greater than in vivo bioavailability. Correlation between in vitro release (%) and in vivo absorption (%) showed good linearity (gamma=0.8805-0.9999).

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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The effect of soybean oil refuse powder used as vehicle on the absorption of oxolinic acid in chickens under fasting and nonfasting conditions and the correlation with in vitro dissolution

Hamamoto

Koike

Machida

2001

Vet Pharm & Therapeutics

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“…Ethanol was used to dissolve BRC in the gel, because BRC has very poor water solubility (1 g/l to 0.0024 g/l for the pH range of 2 to 6). 33) It acts as an enhancer by increasing the stratum corneum lipids fluidity and it increases solubility of the solute in the lipids. 34) Ethanol facilitates the penetration and higher penetration values were observed when higher amount of ethanol was used in the formulation.…”

Section: Fig 2 Blood Brc Concentrations After Application Of Enhancmentioning

confidence: 99%

Transdermal Administration of Bromocriptine.

Değim

Acartürk

Erdoğan

et al. 2003

Biological & Pharmaceutical Bulletin

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Bromocriptine (BRC) is a semi-synthetic ergot alkaloid and it has been used for the treatment of diseases caused by hyperprolactinemia and for some neurological disorders as a dopamine agonist in clinics.1) BRC is mainly used for the inhibition of lactation, 2) treatment of menstrual disorders, 3) Parkinson disease, 4) breast tumours, 5) infertility 6) and brain tumours. 7)Bromocriptine is well absorbed through the GI tract but it has low bioavailability because of the hepatic first pass effect, but many patients have complained with GI side effects, headache and dizziness.4) The long acting injectable form of BRC has been developed 2) and it avoids the gastrointestinal side effects but it is expensive and cannot be self-administered.An alternative delivery route such as vaginal application of BRC has been reported. 8,9) Bromocriptine is well absorbed from vagina. Acartürk and Altug have studied the vaginal ring formulation of BRC with polydimethylsiloxane in vitro and in vivo in rabbits. 10,11) It was shown that the controlled release intravaginal ring containing BRC was found to be effective to decrease the plasma prolactin level in rabbits.BRC has also used for the treatment of Parkinson disease and the transdermal administration may be more useful than vaginal administration, being not gender limited. Transdermal delivery of drugs is also very convenient from the application point of view and it offers several advantages over the other routes of drug administration and termination of the drug input is possible in problematic cases. 12,13) Transdermal systems represent one of the most successful non-oral systemic drug delivery system. However, because of limitations of the technology, the physical, chemical nature of the compounds and also lack of the knowledge about penetration mechanisms, transdermal drug delivery is not suited to all drugs and it needs to be justified for the therapies.14)The penetration mechanisms, histopathological hazards of the enhancers and vehicles need to be clarified.The aim of this study was to investigate an alternative delivery route for BRC. Several topical BRC gel formulations were developed using Carbopol (C-934), Daichitosan (CH) and Gantrez-SP215 (G-SP215) and applied to rabbits. Commercially available BRC tablets (Parlodel ® ) were also given to rabbits orally and plasma levels were compared. Two different penetration enhancers, sodium taurocholate (ST) and ethoxydiglycol-Transcutol ® (TR) were also used to improve BRC penetration. Preparation of Gel Formulations For formation of the gel, CH or C-934 was dispersed in water then acetic acid or 0.01 N NaOH was added, respectively. BRC was dissolved in absolute ethanol and then mixed with the gel. TR or ST was added for the preparation of CH-ST or CH-TR gel. G-SP215 solution in ethanol was neutralised by triethanolamine and mixed with BRC solution in ethanol. Bromocriptine (BRC) has been mainly used for the inhibition of lactation, treatment of menstrual disorders, Parkinson disease, breast tumours, infertility and brain tumo...

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In Vitro-ln Vivo Correlation for Modified-Release Formulations

Drewe

Guitard

1993

Journal of Pharmaceutical Sciences

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Relevance of pH Dependency on in Vitro Release of Bromocriptine from a Modified-Release Formulation

Cited by 8 publications

References 12 publications

The effect of soybean oil refuse powder used as vehicle on the absorption of oxolinic acid in chickens under fasting and nonfasting conditions and the correlation with in vitro dissolution

The effect of soybean oil refuse powder used as vehicle on the absorption of oxolinic acid in chickens under fasting and nonfasting conditions and the correlation with in vitro dissolution

Transdermal Administration of Bromocriptine.

In Vitro-ln Vivo Correlation for Modified-Release Formulations

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