Association of heart rate response with scan and left ventricular function on adenosine stress myocardial perfusion imaging.

To evaluate the association of heart rate (HR) response with abnormal scan and/or left ventricular (LV) function in patients undergoing adenosine myocardial perfusion imaging, we prospectively studied 164 consecutive patients who underwent a standard adenosine stress test (without exercise) and myocardial perfusion imaging (MPI) using technetium-99m sestamibi radioisotope. Change in HR was calculated by subtracting HR at rest from peak HR. The percentage change in HR was calculated. All patients underwent stress and resting single photon emission computed tomography (SPECT) imaging. Left ventricular ejection fraction (EF) was calculated using gated SPECT. Mean age was 54 ± 11.7 years and 126 of the patients (72%) were men. We divided the patients into 2 groups: group 1(42 patients, 25%) had normal scans and group 2(122 patients, 74.3%) had abnormal scans; abnormal scans were defined as presence of either fixed defects, reversible defects, or both. Average HR increased by 35 beats/min in the normal scan group compared with 23 beats/min in the abnormal scan group (p=0.002). Sixty four (64) patients (39%) had reduced EF (<45%). This group had an average HR and percentage HR increase of 23 beats/min (27%) compared with an increase of 35 beats/min (38%) in patients with normal EF (p=0.002 and p=0.02, respectively). Thus, a diminished HR response had a significant association with both an abnormal scan and reduced EF on adenosine MPI.

Evaluation of serum lipid profile in patients with hypertension living in a coastal region of Bangladesh.

Serum lipid levels are greatly controlled by genetic and environmental factors. When investigating the relationship between lipid disturbances and hypertension it is necessary to use local data on blood lipid profile in each region. Unfortunately, there is no literature reporting the lipid profile in hypertensive patients in coastal region of Bangladesh. The present study was conducted as a case-control study with 100 hypertensive patients as cases and equal number of normotensive individuals as controls. Socio-demographic, anthropometric and clinical data of both patients and controls were collected. Serum lipid parameters were analyzed biochemically. Independent sample t-test, Chi-Square test and Pearson's correlation test were done for the statistical analysis using the statistical software package SPSS. Our study found that serum total cholesterol (TC), triglyceride (TG), LDL, VLDL, TC/HDL, LDL/HDL were significantly higher (p<0.05) whereas the level of HDL cholesterol was significantly lower in hypertensive patients as compared to control subjects (p<0.05). Pearson's correlation analysis reveals that HDL cholesterol was inversely correlated with systolic and diastolic blood pressure in both patient and control groups. But serum TC, TG, LDL and HDL cholesterol were directly correlated with systolic and diastolic blood pressure in both groups. This study explored that hypertensive patients have higher level of TC, TG, LDL and VLDL cholesterol but lower level of HDL cholesterol than the normotensive subjects. Routine investigation of lipid profile in hypertensive patients may help to prevent further aggravation and risks of coronary artery diseases.

Resistant hypertension: underlying causes and treatment.

Resistant hypertension (RH) is defined as failure to achieve goal blood pressure while receiving a 3 drug regimen at optimal doses that includes a diuretic. The exact prevalence of resistant hypertension is unknown which may vary from 5% to 50%. Patient or clinician-related factors contributing to resistant hypertension include patient's non-adherence to antihypertensive therapy, White-coat effect and pseudo-hypertension and life style factors (Obesity, alcohol, smoking, dietary sodium etc). Several drugs may induce pre-existing hypertension where non-steroidal anti-inflammatory drugs are usually the most common due to their frequent use; whereas oral contraceptives, sympathomimetics (decongestants, anorectics), adrenal steroids and antineoplastic drugs targeting the vascular endothelial growth factor (VEGF) pathway has a good deal of contribution to resistant hypertension. Most common secondary causes of resistant hypertension are obstructive sleep apnea, renal artery stenosis, renal parenchymal disease, and primary aldosteronism while some uncommon causes such as pheochromocytoma, Cushing's disease, thyroid and parathyroid dysfunction; and aortic coarctation also contribute to resistant hypertension. Both pharmacological and non-pharmacological treatments are available for the management of resistant hypertension. This article reviews the prevalence, symptoms, causes and treatment of resistant hypertension.

Chemical and biological studies on a series of novel (trans-(1R,2R)-, trans-(1S,2S)-, and cis-1,2-diaminocyclohexane)platinum(IV) carboxylate complexes.

A series of novel platinum(IV) complexes of the type DACH-PtIV-trans-(Y)2-cis-X (where DACH = trans-(1R,2R)-, trans-(1S,2S)-, or cis-1,2-diaminocyclohexane; X = diacetate, oxalate, malonate, methylmalonate, cyclobutanecarboxylate (CBCA), or 1,1-cyclobutanedicarboxylate (CB-DCA); and Y = acetate or trifluoroacetate) has been synthesized and characterized by elemental analysis, IR, and 195Pt-NMR spectroscopy. The compounds have been tested against cisplatin-sensitive L1210/0 leukemia, cisplatin-resistant L1210/DDP leukemia, and M5076 reticulosarcoma cell lines in vivo. Most of these analogs displayed reasonable activity against L1210/0 cells (%T/C = 135 to > 700). There were no gross differences in activity between analogs containing isomers of DACH. Selected compounds were evaluated against L1210/DDP tumor models in which they demonstrated reduced but significant activity compared with activity in the L1210/0 model. Interestingly, complex 20, PtIV(trans-1R,2R-DACH)-trans-(acetate)2-methylmalonate, was highly active against M5076, although it had no activity against the L1210 lines. The results demonstrate that specific combinations of axial and equatorial carboxylate ligands, together with the DACH carrier ligand, can favorably modulate the antitumor properties of platinum complexes and enhance circumvention of cisplatin resistance.

Synthesis and antitumor activity of 1,2-diaminocyclohexane platinum(IV) complexes.

The synthesis, characterization, and antitumor activity of a series of platinum(IV) complexes of the type DACH-PtIV(X)2Y (where DACH = trans-dl, or trans-l-1,2-diaminocyclohexane, X = OH or Cl, and Y = oxalato, malonato, methylmalonato, tartronato, ketomalonato, 1,1-cyclopropanedicarboxylato, or 1,1-cyclobutanedicarboxylato, are described. These complexes have been characterized by elemental analysis, HPLC, and infrared and 195Pt NMR spectroscopic techniques. The complexes had good in vitro cytotoxic activity (IC50 = 0.14-7.6 micrograms/ml) and were highly active in vivo against leukemia L1210 cells (%T/C = 152- > 600, cisplatin = 218). In addition, excellent in vivo antitumor activities against B16 melanoma (%T/C = 309), M5076 reticulosarcoma (100% cures) and cisplatin-resistant L1210/DDP (%T/C = 217) cell lines were also exhibited by an analog selected for further evaluation.

Modulatory effect of axial and equatorial ligands on antitumor activities of trans-1R,2R-diaminocyclohexane platinum(IV) complexes.

Acquired drug resistance is a major drawback of using cisplatin in the treatment of cancer; however, platinum analogs containing the 1,2-diaminocyclohexane (DACH) ligand can overcome this resistance. DACH can exist as the trans-1R,2R, trans-1S,2S or cis isomer, and we have previously established that the R,R form of DACH-Pt(II) complex is in general superior. Here, we have examined if specific axial and/or equatorial ligands attached to a platinum(IV) center can modulate the antitumor activities of R,R-DACH-Pt complexes in murine tumor models in vivo. Four series of R,R-DACH-Pt complexes were synthesized, with each series consisting of one platinum(II) complex and three corresponding platinum(IV) analogs, each differing by the chemical nature of the axial ligand (chloro, hydroxo or acetato). Combination of axial chloro with equatorial chloro (Cl2Cl2), 1,1-cyclobutanedicarboxylato (Cl2CBDCA), tartronato (Cl2Tart) or methylmalonato (Cl2MeMal) gave activities which were similar to or greater than those of the corresponding platinum(II) complex in the cisplatin-sensitive L1210/0 or cisplatin-resistant L1210/DDP leukemia and solid M5076 reticulosarcoma models. The exception was the complex Cl2Cl2 in the M5076 model, which was 2-fold less sensitive to this platinum(IV) complex than to the corresponding platinum(II) analog. Axial hydroxo or acetato platinum(IV) complexes were effective in combination with equatorial chloro ([OH]2Cl2 or Ac2Cl2) or tartronato ([OH]2Tart or Ac2Tart) against L1210/0, L1210/DDP and M5076 cells, but effective only against M5076 cells when combined with equatorial 1,1-cyclobutanedicarboxylato (CBDCA) or methylmalonato. The results demonstrated a profound effect of axial and equatorial ligands on the antitumor activities of R,R-DACH-Pt(IV) complexes. Furthermore, these modulatory effects could be influenced strongly by the tumor model. The interesting finding from this structure-activity study was the emergence of R,R-DACH([OH]2Cl2)Pt(IV) complex as a 'lead' analog worthy of further exploration.

Lipophilic platinum complexes entrapped in liposomes: improved stability and preserved antitumor activity with complexes containing linear alkyl carboxylato leaving groups.

Lipophilic diaminocyclohexane (DACH) platinum complexes have shown significant promise in preclinical studies. One of these compounds, cis-bis-neodecanoato-trans-R,R-1,2-diaminocyclohexaneplatinum++ +(II) (NDDP), which contains two branched leaving groups of 10 carbons, showed a favorable toxicity profile in a liposomal formulation in early clinical trials. However, like many other DACH platinum compounds with branched leaving groups, it is unstable within the liposomes, thus preventing its widespread clinical evaluation. We studied the effect of the configuration of leaving groups on intraliposomal complex stability by studying a series of DACH platinum complexes containing linear alkyl carboxylato leaving groups of 5-18 carbons. The entrapment efficiency was greater than 90% for all liposomal preparations of the complexes and was independent of lipid composition and length of the leaving group. The drug leakage from the liposomes was minimal, but was directly related to the length of the leaving group. Intraliposomal stability was inversely related to the length of the leaving group and the content of DMPG (dimyristoyl phosphatidylglycerol) in the liposomes. The effect of length of leaving group on intraliposomal stability was minimal in compounds with leaving groups smaller than 10 carbons, but very pronounced in compounds with longer leaving groups. Stable liposomal formulations of selected compounds with leaving groups of 6 and 10 carbons had significant in vivo antitumor activity against both L1210/S and L1210/PDD leukemias. The results indicate (1) that compounds with linear leaving groups are much more stable within DMPG-containing liposomes than compounds with branched leaving groups and (2) that DMPG is required for in vivo antitumor activity. Stable and active liposomal formulations of selected compounds with linear leaving groups have been identified. These formulations are candidates for clinical development.

Preparation and characterization of liposomes containing a lipophilic cisplatin derivative for clinical use.

Cis-bis-neodecanoato-trans-R,R-1,2 diaminocyclohexane platinum(II) (NDDP) is a lipophilic cisplatin derivative that has been formulated entrapped in multilamellar liposomes composed of dimyristoylphosphatidyl choline (DMPC) and dimyristoylphosphatidyl glycerol (DMPG). A phase I clinical study with liposome-entrapped NDDP (L-NDDP) administered i.v. every 4 weeks has been recently completed. L-NDDP was synthesized, manufactured, and reconstituted for clinical use in our laboratories. L-NDDP was prepared as a lyophilized powder containing the NDDP and the phospholipids (NDDP-lipid weight ratio 1:15; DMPC-DMPG molar ratio 7:3). The liposome suspension was obtained on the day of use just before administration to the patients by adding normal saline (final concentration 1 mg NDDP/ml) and shaking in a water-bath shaker at room temperature according to an established protocol. A total of 54 batches of lyophilized L-NDDP were prepared. Physical appearance, phospholipid content and integrity, and elemental platinum content were determined in all batches and found to be reproducible. All batches contained < 0.24 ng/ml endotoxin. The amount of residual organic solvents was < 0.05 per cent. In all reconstituted doses, drug entrapment was > 90 per cent, and the proportion of liposomes measuring > 5 microns was < 20 per cent. Our results show that reproducible batches of liposomal preparations of new compounds can be prepared in the laboratory facilities of academic institutions, thus allowing for early clinical trials with novel therapeutic agents.

Antitumor activity of isomeric 1,2-diaminocyclohexane platinum(IV) complexes.

Acquired drug resistance is a major drawback of using cisplatin in the treatment of cancer; however, analogs containing the 1,2-diaminocyclohexane (DACH) ligand can overcome this resistance. DACH can exist as the trans-1R,2R, trans-1S,2S or cis isomer, and we have examined whether specific isomers coordinated to a platinum(IV) center can modulate antitumor activities in murine tumor models in vivo. Ten isomeric series of DACH-Pt(IV) complexes were synthesized, each series containing a different combination of axial and equatorial ligands and varying only by the isomeric form of the DACH ligand. Among the ten series, seven clearly indicated superiority of the (R,R)-DACH-Pt(IV) complex against leukemia L1210/0 cells, while in three the R,R and S,S configurations gave similar efficacies which were better than that of the corresponding cis analog. In three out of the ten series, the antitumor activities of the S,S and cis complexes were similar, in six the cis analogs were the least effective, and in the remaining one the cis analog was superior to S,S. One series of complexes with axial chloro ligands and an equatorial 1,1-cyclobutanedicarboxylato group, which had produced the efficacy ranking R,R > cis > S,S in the L1210/0 model, gave S,S > R,R > cis against cisplatin-resistant L1210/DDP cells, R,R = S,S > cis against B16 melanoma cells, and R,R = S,S = cis against M5076 reticulosarcoma cells. The results demonstrate that profound variation can occur in antitumor activities among isomeric forms of the DACH-Pt(IV) complex. However, the (R,R)-DACH-Pt(IV) complexes appear to be of greater interest overall.

X-ray crystal structure of tetrachloro(trans-d,l-1,2-diaminocyclohexane) platinum(IV) complex: a potential anticancer agent.

Tetrachloro(trans-d,l-1,2-diaminocyclohexane)platinum(IV) complex (tetraplatin or ormaplatin) has been recognized as a potential anticancer agent. We have determined the crystal structure of this compound by x-ray single crystal diffraction. It has a unique space group and rare molecular packing. Parameters are as follows: space group R3c (rhombohedral), a = 26.425(4) A, alpha = 54.50(1) degrees; V = 11375A3, Z = 36. The coordination about Pt atoms is a slightly distorted octahedron owing to the presence of the geometrically strained five-membered ring (avg. N-Pt-N angle = 82.9 degrees). An intricate network of intermolecular hydrogen bonds holds the crystal lattice together. Three independent ormaplatin molecules surround each water molecule, forming the three shortest A...B contacts and thus the three strongest hydrogen bonds.

Modulation of cytotoxicity and cellular pharmacology of 1,2-diaminocyclohexane platinum (IV) complexes mediated by axial and equatorial ligands.

Isomers (R,R-, S,S-, and cis-) of 1,2-diaminocyclohexane (DACH) platinum(IV) complexes with selected axial and equatorial ligands were synthesized and evaluated for in vitro antitumor activity, cellular uptake, and total DNA-Pt adducts. L1210 cells, sensitive to cis-diamminedichloroplatinum(II) (CDDP) and tetraplatin (L1210/0), 160-fold resistant to CDDP [L1210/diamminedichloroplatinum (DDP)], or 70-fold resistant to tetraplatin (L1210/DACH), were used in conjunction with compounds having the general structure DACH-Pt(IV)-X2Y2, where X and Y are axial and equatorial ligands and X2Y2 are specifically Cl2Cl2,Ac2Cl2, (TFA)2Cl2, (OH)2Cl2, and Cl2CBDCA (Cl, chloro; Ac, acetato; TFA, trifluoroacetato; OH, hydroxo; CBDCA, 1,1-cyclobutanedicarboxylato). Comparison of cytotoxicities between isomers of Cl2Cl2,Ac2Cl2, or Cl2CBDCA indicated that R,R-isomers were the most effective against all three cell lines. The relatively lower activity of the S,S- and cis-isomers was cell line dependent: against L1210/DACH, both isomers of Cl2Cl2 were only 2- to 3-fold less effective, and this contrasted with 7- and 26-fold lower cytotoxicities, respectively, against L1210/DDP. Cross-resistance factors in the L1210/DDP and L1210/DACH lines depended on both isomeric form and the nature of axial or equatorial ligand. The L1210/DDP cells were 6- to 9-fold cross-resistant to the R,R-isomer, 8- to 15-fold to S,S-isomer, and 13- to 38-fold to cis-isomer. The L1210/DACH line was only 4- to 7-fold cross-resistant to the three isomers of Ac2Cl2 but cross-resistance to the isomers was 47- to 79-fold for Cl2Cl2 and 22- to 56-fold for Cl2CBDCA complexes. Compared with CDDP, accumulation (2 h at 100 microM drug concentration) of Ac2Cl2 in the three L1210 cell lines was 26-50%, while uptake of Cl2Cl2 and (TFA)2Cl2 was 100-170% and 320-570%, respectively. The greatest DNA binding was seen with Cl2Cl2 in all cell lines, followed by (TFA)2Cl2, CDDP, and Ac2Cl2. DNA binding correlated directly with potency (1/concentration producing 50% inhibition) in the L1210/0 model (r = 0.973, P < 0.016) but not in the L1210/DDP and L1210/DACH models. Accumulation and DNA-binding studies indicated that binding efficiency to DNA was: Cl2Cl2 > Ac2Cl2 > CDDP > (TFA)2Cl2. In a nonreducing environment, the Pt(IV) complexes (20 microM) did not react with salmon sperm DNA. Reduced glutathione (100 microM), as a reducing agent, rendered full binding capacity to Cl2Cl2; binding was 25-30% of the expected maximum for (TFA)2Cl2, while Ac2Cl2 remained inert.(ABSTRACT TRUNCATED AT 400 WORDS)

Cellular pharmacology of liposomal cis-bis-neodecanoato-trans-R,R-1,2-diaminocyclohexaneplatinum(II) in A2780/S and A2780/PDD cells.

We studied the cytotoxicity, cellular accumulation, and DNA interactions induced by liposome-entrapped NDDP (L-NDDP) and cisplatin in A2780 human ovarian carcinoma cells sensitive (A2780/S) and resistant (A2780/PDD) to cisplatin. L-NDDP was 2-fold more cytotoxic than cisplatin against A2780/S cells with 5-h or 24-h drug exposure. Both cell lines were equally sensitive to L-NDDP, while A2780/PDD cells were 4-fold resistant to cisplatin (resistance indexes, 1.30-1.85 and 4.02-4.50, respectively). Using a drug exposure time of 24 h, L-NDDP cytotoxicity was independent of the liposome composition used, whereas with shorter drug exposure (5 h), the cytotoxicity of L-NDDP was directly related to the relative content of DMPG in the liposome carrier. However, changes in liposome composition or drug exposure time did not alter the resistance index of L-NDDP in this cell system. The cellular accumulation of L-NDDP was similar in both cell lines and 2- to 5-fold higher than that of cisplatin in A2780/S cells, whereas the cellular accumulation of cisplatin was reduced by 2- to 3-fold in A2780/PDD cells. The presence of DMPG in the lipid bilayer enhanced by 2-fold the cellular accumulation of L-NDDP, in good correlation with the direct relation between cytotoxic potency of L-NDDP and the presence of DMPG in the liposome carrier. Pt/DNA levels were determined at different time points after drug exposure for 1 h. Peak Pt/DNA levels were observed at 6 h for cisplatin and at 9 h for L-NDDP. Peak Pt/DNA levels and Pt/DNA over time of L-NDDP were about 1.5- and 3-fold higher than those of cisplatin in A2780/S and A2780/PDD cells, respectively, when equimolar concentrations of both drugs were used. Cisplatin induced significant DNA interstrand and DNA-protein cross-links in A2780/S cells, and a good correlation was observed between cytotoxicity against both cell lines and both types of lesions. In contrast, equimolar concentrations of L-NDDP induced only minimal DNA interstrand cross-links in either cell line.(ABSTRACT TRUNCATED AT 400 WORDS)

Synthesis and antitumor activity of ammine/amine platinum(II) and (IV) complexes.

Dimeric platinum complexes, [Pt(RNH2)I2]2 (where R = H, methyl, ethyl, isopropyl, cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl), have been synthesized by reactions of diiodoplatinum compounds with perchloric acid in water/ethanol solutions. The dimerization varies from several hours to a few days depending upon the length of the carbon chain in the alkylamines and the process can be conveniently monitored by 195Pt NMR spectroscopy. All these dimers exhibit two closely separated resonances around -4000 ppm (vs K2PtCl4 at -1620 ppm) in dimethylformamide. Reactions of [Pt(NH3)I2]2 with alkylamines do not yield the desired mixed ammine/amine complexes, which are obtained subsequently by treatment of the alkylamine dimer [Pt(RNH2)I2]2 with ammonium hydroxide in water. By using this latter procedure, a novel class of ammine/amine platinum complexes of the type PtII(NH3)(RNH2)Cl2, PtIV(NH3)(RNH2)X2A2, and PtIV(NH3)(RNH2)(CBDCA)A2.H2O, where X2 = chloro or 1,1-cyclobutanedicarboxylato (CBDCA), A = OH, Cl, or OCOCH3, have been synthesized and characterized by elemental analysis, infrared, and 195Pt NMR spectroscopic techniques. The alicyclic ammine/amine Pt(II) complexes, where R is C3-C6 were selected as representative of the class to undergo antitumor evaluations. The compounds had excellent activity against murine leukemic L1210/0 cells with cyclobutylamine-, cyclopentylamine- and cyclohexylamine-containing complexes demonstrating cytotoxicity superior to that of the clinically established cisplatin.

Differential antitumor activity and toxicity of isomeric 1,2-diaminocyclohexane platinum (II) complexes.

Acquired resistance is a main drawback of using cisplatin in cancer chemotherapy; however, analogs containing the 1,2-diaminocyclohexane (DACH) ligand can overcome this resistance. Because DACH can exist as the trans-1R,2R, trans-1S,2S or cis isomer, the antitumor activity and toxicity of individual isomers of both DACH(sulfato)Pt(II) and DACH(1,1-cyclobutanedicarboxylato)Pt(II) complexes have been examined. At optimal doses, differences in antitumor activities among the three isomers were moderately dependent on the in vivo tumor models (L1210/0, L1210/DDP, B16 and M5076). However, differences in efficacy among these isomers were greatly modulated by the sulfate or 1,1-cyclobutanedicarboxylate (CBDCA) leaving ligands. Thus, the trans isomers (R,R and/or S,S) of the sulfate complex generally had greater activities than the corresponding cis form, while the cis configuration appeared to be superior in the complex containing the CBDCA ligand. The isomers were also compared for their potential to elicit myelosuppression and kidney toxicity. Of the six isomers investigated, cis-DACH(CBDCA)Pt(II) was myelosuppressive, and the corresponding R,R and S,S isomers were mildly nephrotoxic. No such toxicities were apparent with any of the sulfate complexes. From these studies, particularly with the cisplatin-resistant L1210/DDP cell line, the R,R isomers are evidently the most interesting. However, it is possible that other leaving ligands or tumor models may indicate either S,S- or cis-DACH as the isomer worthy of greater interest.

Synthesis and biological studies of new lipid-soluble cisplatin analogues entrapped in liposomes.

A series of highly lipophilic platinum(II) complexes of the type cis-[(RNH2)2PtX2] have been synthesized, where R = ethyl, propyl, isopropyl, butyl, cyclopropyl, cyclopentyl, or neopentyl and X = either long-chain carboxylate, such as decanoate (C10), laurate (C12), myristate (C14), heptadecanoate (C17), stearate (C18), nonadecanoate (C19), or 2,2,3,3-tetramethylcyclopropylcarboxylate, or branched-chain carboxylate, such as neopentanoate, neohexanoate, neoheptanoate, neononanoate, or neodecanoate. These complexes have been characterized by elemental analysis, IR, and 13C and 195Pt NMR spectroscopic techniques. The platinum complexes were entrapped in multilamellar vesicles composed of dimyristoyl phosphatidylcholine (DMPC) and dimyristoyl phosphatidylglycerol (DMPG) at a 7:3 molar ratio and tested for antitumor activity. The entrapment efficiency of liposomal platinum (L-Pt) complexes ranged from 60 to 100%. The percentage of T/C obtained after a single i.p. injection of the optimal dose of L-Pt complexes tested against L1210 leukemia ranged from 90 to 125%. These L-Pt preparations did not show significant antitumor activity in mice.

Toxicity and efficacy studies on a series of lipid-soluble dineodecanoato(trans-R,R- and trans-S,S-1,2-diaminocyclohexane) platinum (II) complexes entrapped in liposomes.

A number of highly lipophilic dineodecanoato(trans-R,R- and trans-S,S-1,2-diaminocyclohexane) platinum (II) complexes were entrapped in multilamellar vesicles composed of dimyristoyl phosphatidylcholine and dimyristoyl phosphatidyl-glycerol at a molar ratio of 7:3. The entrapment efficiency and stability of liposomal platinum (L-Pt) preparations was greater than 90%. The subacute mouse LD50 of L-Pt preparations tested ranged from 60 to 104 mg/kg. All L-Pt preparations tested had no significant nephrotoxicity at the LD50 dose except for L-Pt 5, which caused renal dysfunctions (as evidenced by elevated blood urea nitrogen levels) at the LD50 dose. L-Pt preparations had shown good in vivo antitumor activity against i.p. L1210 leukemia when an optimal dose was administered i.p. to mice on days 1, 5 and 9 (% T/C 230-300; cisplatin 220). L-Pt preparations were also markedly active, by the i.p. route, against L1210 leukemia resistant to cisplatin (% T/C 237-355; cisplatin 112). All L-Pt preparations exhibited significant antitumor activity against B16 melanoma when administered i.p. on day 1 (% T/C 144-155; cisplatin 161). L-Pt 1, 3 and 5 were all tested by the i.v. route on days 4, 8 and 12 against M5076 reticulosarcoma, but none of these preparations showed any significant antitumor activity against this tumor system (% T/C 120-127; cisplatin 173). Current studies aimed at optimizing the liposomal formulation of these compounds should result in the selection of a single isomeric L-Pt formulation for clinical development.

Pharmacokinetics of liposome-entrapped cis-bis-neodecanoato-trans-R,R-1,2-diaminocyclohexane platinum(II) and cisplatin given i.v. and i.p. in the rat.

The pharmacokinetics of liposome-entrapped cis-bis-neodecanoato-trans-R,R-1,2-diaminocyclohexane platinum(II) (L-NDDP) and cisplatin (CDDP) were studied after i.v. and i.p. administration of an equimolar dose (11 and 5 mg/kg for L-NDDP and CDDP, respectively) in the rat. The systemic absorption following i.p. administration was faster in rats receiving CDDP than in those receiving L-NDDP. Peak serum platinum (Pt) levels were observed at 30 min and 12 h after the i.p. administration of CDDP and L-NDDP, respectively. Administration by the i.v. route did not significantly alter the serum Pt levels for either compound. However, serum Pt levels were 2-3 times greater in animals treated with L-NDDP than in those treated with CDDP. The estimated pharmacokinetic parameters for each drug were independent of the route of administration, except for the clearance (Cl) of CDDP, which increased 2-fold following i.p. administration. In addition, significant differences in pharmacokinetic parameters were observed between drug-treatment groups that were independent of the route of administration: the serum Pt area under the concentration-time curve (AUC) was higher and the volume of distribution at steady state (Vdss) was lower in rats receiving L-NDDP. Pt levels measured at 6 h in the peritoneal fluid, peritoneal tissue, and intestine of rats receiving i.p. L-NDDP were higher than those observed in rats receiving either i.v. L-NDDP or CDDP by either route. Pt levels measured in the liver and spleen of rats receiving L-NDDP were independent of the route of administration and were significantly higher than those determined in rats treated with CDDP. In contrast, kidney Pt levels were lower in rats receiving L-NDDP than in rats receiving CDDP by either route. These results suggest that the prolongation of the mean retention time of L-NDDP in the peritoneum achieved after i.p. administration without compromising the systemic distribution of the drug may result in a significant enhancement of the therapeutic efficacy of L-NDDP against malignancies confined to the peritoneal cavity as compared with that of i.p. CDDP.

Chemical and biological studies on a series of lipid-soluble (trans-(R,R)- and -(S,S)-1,2-diaminocyclohexane)platinum(II) complexes incorporated in liposomes.

cis-Bis(neodecanoato)(trans-(R,R)-1,2-diaminocyclohexane)platinum( II) [L-NDDP] is a liposome incorporated lipophilic cisplatin analogue that has shown promising antitumor activity against tumors resistant to cisplatin and liver metastases in mice. L-NDDP is currently under clinical evaluation. However, NDDP is an isomeric mixture of different species having various isomeric neodecanoic moities as liganded leaving groups. A series of new highly lipid-soluble cis-bis(neodecanoato)(trans-(R,R)- and -(S,S)-1,2-diaminocyclohexane)platinum(II) [Pt] complexes, using single isomers of neodecanoic acid, were synthesized and characterized by analytical and spectroscopic techniques (infrared and 195Pt NMR). Multilamellar vesicles (MLVs) composed of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylglycerol (DMPG) at a molar ratio of 7:3 were used as carriers of the Pt complexes. The efficiency of incorporation of the liposomal-platinum (L-Pt) preparations was greater than 95% and stability in normal saline at 4 degrees C was greater than 95% at day 14 in each case. The iv LD50 values of all L-Pt preparations tested were in the range of 62.3 to 104 mg/kg. The % T/C obtained after a single ip injection of the optimal dose of L-Pt preparations against L1210 leukemia was in the range of 150 to 253 (160 for cisplatin). When a multiple ip injection schedule was used (on days 1, 5, and 9) the L-Pt preparations of R,R complexes (1, 7, and 9) were more active than cisplatin at the optimal dose (% T/C = 257 for each vs 220 for cisplatin). The L-Pt preparations of R,R complexes were also markedly active against L1210 leukemia resistant to cisplatin (% T/C 355, 231, and 185 respectively vs 112 for cisplatin). These studies show that the single isomers of NDDP are comparable to the original isomeric mixture in terms of toxicity and biological activity.

Antitumor and DNA-binding properties of a group of oligomeric complexes of Pt(II) and Pt(IV).

The antitumor and DNA-binding properties of a group of oligomeric platinum(II) and platinum(IV) complexes are described. The compounds, having the stoichiometry [cis-PtII(X)2(mu-OH)]2(NO3)2, where X is NH3, NH2CH2CH3, and NH2CH(CH3)2, were found to be inactive or only weakly active against L-1210 leukemia. In vitro studies involving PM2-DNA show that these compounds bind to and unwind closed circular DNA in a manner similar to cis-PtII-(NH3)2Cl2. The Pt(IV) complexes produced by hydrogen peroxide oxidation of the Pt(II) dimers are inactive as antitumor agents and are incapable of unwinding PM2-DNA. The cyclotrimer [cis-PtII(RR-DACH)(mu-OH)]3(NO3)3, where RR-DACH is (R,R)-1,2 diaminocyclohexane, exhibits potent antitumor activity against L-1210 leukemia and modest activities with B-16 and M5076 tumor lines. This compound platinates DNA, causing DNA unwinding and mobility shifts.

Phase I clinical and pharmacological study of liposome-entrapped cis-bis-neodecanoato-trans-R,R-1,2-diaminocyclohexane platinum(II).

cis-Bis-neodecanoato-trans-R,R-1,2-diaminocyclohexaneplatinum++ +(II) (NDDP) is a liposome dependent cisplatin analogue since the liposome carrier is required for its i.v. administration and for its biological activity. A Phase I study of liposome entrapped NDDP (L-NDDP) was performed using a single i.v. injection every 4 weeks. L-NDDP was prepared and characterized at M. D. Anderson Cancer Center. The maximum tolerated dose of L-NDDP was 312.5 mg/m2. The dose-limiting toxicity was myelosuppression, affecting all three blood cell lineages. The granulocyte nadir occurred on days 14-18, and the platelet nadir consistently earlier (days 11-12). The median day of recovery of blood cell counts was day 21 (range, 18-32). Other toxicities included grade 2 nausea and vomiting, fever consisting of a single temperature spike in most patients, grade 1 diarrhea after 60% of courses, and grade 1-2 malaise lasting for 5-10 days after the infusion in 73% of courses. Transient alanine aminotransferase elevations without clinical relevance were common. No signs of renal dysfunction or ototoxicity were observed. One patient with a preexisting peripheral neuropathy showed some progression of the neuropathy after a cumulative dose of 1605 mg/m2. Except for fever and transient liver dysfunction, no liposome related side effects were observed in spite of the high doses of lipid administered. The blood clearance of L-NDDP fits a two-compartment model at lower doses and a single-compartment model at the maximum tolerated dose, suggesting that saturation of the reticuloendothelial organs occurs at the maximum tolerated dose. Two minimal responses were observed. L-NDDP has a toxicity profile similar to that of carboplatin. Phase II studies to address the issue of how the therapeutic index of platinum compounds is affected by liposome entrapment are being planned.