1. Structural and physicochemical aspects of hydrochlorothiazide co-crystals
Jian-Rong Wang, Chanjuan Ye and Xuefeng Mei*. CrystEngComm,2014, 16, 6996–7003
Hydrochlorothiazide (HCT, Scheme 1) is a diuretic drug used for the treatment of hypertension and edemas. It belongs to class IV compounds according to the Biopharmaceutics Classification System (BCS), suffering from both low solubility (0.25 g L−1) and low permeability (log P = −0.07). The low bioavailability of HCT is partially attributed to its poor aqueous solubility. Attempts have been made by several groups to improve the solubility of HCT using various techniques. Captopril is used as a water soluble carrier and the solubility of HCT was enhanced from 0.25 mg mL−1 to 0.62 mg mL−1 when different concentrations of the carrier were applied. An inclusion complex of HCT with β-cyclodextrin had also been synthesized to overcome the solubility limitations. The co-crystallization approach was recently applied to HCT in order to alter its solubility. The synthesis and structure determination of co-crystals of HCT and isonicotinamide were reported by Zaworotko et al. Co-crystals of HCT with nicotinic acid, nicotinamide, succinamide, 4-aminobenzoic acid, resorcin, and pyrogallol have also been reported very recently. The results have shown co-crystallization is a viable approach to improving HCT aqueous solubility.
2. Pharmacological and therapeutic properties of new derivatives of renin inhibitors and endothelin receptor antagonists, and the methods of their determination
Mariusz Stolarczyk,* Anna Apola, Anna Maslanka and Jan Krzek. Anal. Methods,2015, 7, 4419–4442
Combination treatment is preferred in arterial hypertension therapy, and it involves administration of several substances of hypotensive activity. These may be combinations of active substances of various chemical structures and from diﬀerent pharmacological groups. Therefore, there is a need to elaborate the methods of aliskiren determination in the presence of other substances with hypotensive activity. Such analysis includes inter alia determination of aliskiren in the presence of a diuretic, hydrochlorothiazide. Ezzeldin et al. proposed determination of these substances using HPLC and spectrophotometric methods. In case of the HPLC method, methanol mixtures of the examined substances were separated on an Econosphere C-18 column; the mobile phase was a water–acetonitrile mixture (50 : 50 v/v), the flow rate was 0.5 mL min−1, spectrophotometric detection was at a wavelength of 208nm. The retention time was 2.13 min for aliskiren and 3.79 min for hydrochlorothiazide, the linearity range in turn was 5–150 mgmL−1 for aliskiren and 1–50 mgmL−1 for hydrochlorothiazide.
3. A kinetic spectrofluorometric method, aided by chemometrics, for the analysis of sibutramine,indapamide and hydrochlorothiazide compounds found in weight-reducing tonic samples
Ying Guo, Yongnian Ni,* Jinfeng Chena and Serge Kokot. Anal. Methods,2016, 8,197–204
Sibutramine (Table 1) is an appetite inhibitor, plays a major role in the central nervous system, and influences weight-loss by altering neurotransmitters within the brain. While 5–10% weight losses have been claimed by the consumers of sibutramine, this substance can cause serious side eﬀects, and in general, it is a forbidden additive to the weight-reducing tonics. Currently, it has been withdrawn from the markets in most countries. Indapamide and hydrochlorothiazide are diuretics (Table 1), which are generally used for treating hypertension. Both increase urination, and this promotes dehydration in the recipient. In addition, it is not uncommon to find that both the weight reducing compounds, e.g. sibutramine, and the diuretics, e.g. indapamide and hydrochlorothiazide, have been added to the weight-reducing tonics contrary to drug regulations. They were added so as to produce a tonic that reduces body weight faster. Therefore, simultaneous analysis of these substances in weight-reducing foods is clearly important.
4. Determination of losartan potassium in the presence of hydrochlorothiazide via a combination of magnetic solid phase extraction and fluorometry techniques in urine samples
Amir Farnoudian-Habibi, Sahar Kangari, Bakhshali Massoumi and Mehdi Jaymand*. RSC Adv.,2015, 5,102895–102903
This paper describes a novel, sensitive, and selective method for the determination of losartan potassium (LOS) in the presence of hydrochlorothiazide (HCTZ) in human urine samples. According to the drug loading process (as described in the Experimental section), it was found that HCTZ had an interfering role in this study, due to its low loading on the adsorbent surface, and its lack of exhibition of fluorescence emission. Hence, we optimized all parameters, such as pH values, the amount of adsorbent, the extraction time, the desorption solvent, and the desorption time, for MSPE and the determination of LOS.