Comparative pharmacology of tyrosine kinase inhibitors for the treatment of chronic myeloid leukemia

There are 5 BCR/ABL tyrosine kinase inhibitors (TKIs) for the treatment of chronic myeloid leukemia (CML): bosutinib, ponatinib, imatinib, nilotinib and dasatinib. The availability of several therapeutic options raises the possibility of individualizing patient treatment. When evaluating patients’ individual pharmacological profiles, it is important to take into account the differences in the chemical structures of the drugs. Bosutinib, which has a unique interaction and safety profile, is a quinazoline, unlike the other TKIs that have a pyrimidine structure. All 5 TKIs inhibit the BCR/ABL tyrosine kinase, although only ponatinib is active against the strains expressing the T315I mutation. In addition, the 5 TKIs are generally non-selective drugs that can also inhibit other tyrosine kinases, such as cKIT or PDGFR, leading to both benefits in the treatment of some gastrointestinal tumors as well as additional adverse events. These drugs are orally administered and show moderate bioavailability, a large volume of distribution, high protein binding, and elimination after intense metabolism involving various Cytochrome P450 (CYP). They are also substrates of transport proteins and interact with inducers and inhibitors. All TKIs, except bosutinib, can inhibit the activity of transport proteins, leading to important drug interactions. As such, bosutinib is the drug with the better pharmacological profile. There is a close relationship between drug concentration and the beneficial/toxic effects of imatinib, nilotinib, and dasatinib. Therefore, plasma levels should be monitored to optimize patient treatment. Currently, there is no information for ponatinib. Overall, there is a high incidence of adverse events; although these do not usually lead to treatment discontinuation. All 5 TKIs have a similar safety profile; however, each TKI has unique adverse events. Pharmacological differences can identify the drug that is best suited to each patient, helping optimize CML therapy

Farmacología de los azoles

Azole antifungals have different pharmacokinetic characteristics: complete oral absorption for Voriconazole, and to a lesser extent for fluconazole. The absorption of posaconazole and itraconazole increases with food intake. All of them have high tissue distribution with low plasma concentrations, especially low in the case of posaconazole and itraconazole. Posaconazole and itraconazole have high plasmatic protein binding and consequently both have a very low free fraction. Elimination of azole antifungals is through a metabolic pathway with CYP450 isoenzymes, and has a non linear pharmacokinetics with a high risk of interation with other drugs since azoles have the ability of CYP450 isoenzymes inhibition. Possibly the parameter that defines more precisely their efficacy is AUIC with an optimum value near 20, although cut-off values must be defined since some azoles may have difficulty to reach this value

Bioavailability of two oral fentanyl transmucosal formulations in healthy volunteers: an open-label, crossover, randomised study.

Introduction: Oral transmucosal fentanyl citrate (OTFC) was the first product specifically designed for the treatment of breakthrough pain. It is formulated as a sweetened lozenge on a plastic handle (stick) and it is self-administered by the patient, allowing the modulability or flexibility in dosing. Objectives: To prove bioequivalence of a test (T) OTFC product compared to the reference (R) formulation. Material and methods: Open-label, crossover, randomized, single-dose bioequivalence study in healthy volunteers, with two study periods and two sequences, with a washout period of at least 10 days. On each study day, subjects received 400 μg of fentanyl. They were instructed to rub the tablet gently against the buccal mucosa and not to suck on or chew it, and the investigators controlled each administration to ensure that it was consumed during 15 minutes. Given the high pharmacokinetic variability, a two-stage design was established and bioequivalence decision was based on 94.12% confidence intervals of Cmax and AUC0-t geometric means ratio. Results: 36 subjects completed the study according to the protocol. Mean Cmax were similar with both formulations (814.78 pg/ml for T and 781.83 pg/ml for R) and were attained at the same time (40 min. for T and 50 min. for R), and their bioavailability was also very close (AUC0-t: 3920.12 pg.h/ml for T and 3679.39 pg.h/ml for R). Bioequivalence was confirmed for the two primary parameters, Cmax and AUC0-t. No period or sequence effects were observed in any parameter. As bioequivalence was proved in the first phase of the study, it was not necessary to proceed to the second stage. The estimated intraindividual variability was 24.66% and 19.01%, respectively for T and R formulations. Both formulations were well tolerated; 15 mild adverse events were reported. Discussion: The test OTFC product is bioequivalent to the reference one and therefore interchangeable when used clinically. OTFC administration provides faster fentanyl absorption than enteral route and the rate of absorption can be modulated by the administration technique, providing a unique flexibility among all breakthrough pain treatments. The results showed a fast time to maximum concentrations (tmax), in accordance with those originally reported for the reference product, probably favoured by the strict administration technique. Proper patient education is essential to optimize the use of OTFC, as well-trained patients can take advantage of its flexibility to selfcontrolling pain relief

Posibles indicaciones del tratamiento de las enfermedades autoinmunes con tacrolimus

Tacrolimus is an immunosuppressive drug used most successfully as a primary drug to suppress the rejection of transplants. Tacrolimus may also be useful as a novel therapy for autoimmune disease. There are various reports in the bibliography about the use of tacrolimus in the treatment of some autoimmune diseases: inflammatory bowel disease, autoimmune hepatitis, cutaneous, neurologic, renal, endocrine or eye disease. In this review of more than 130 papers, we discuss the rationale for the use of tacrolimus in autoimmune disease and report the clinical experience with the drug in the management of a variety of autoimmune diseases. But, although there are a lot questions that require future research (dose, duration of treatment, when to begin tacrolimus treatment, how to monitor it, etc.), there is also wide experience with tacrolimus in the treatment of this type of disease

Critical appraisal of bilastine for the treatment of allergic rhinoconjunctivitis and urticaria

Bilastine is a second generation antihistamine indicated for the treatment of seasonal or perennial allergic rhinoconjunctivitis and chronic urticaria with a daily dose of 20 mg, in adults and children over 12 years of age. The efficacy of bilastine has been shown to be similar to that of the comparator drugs for the control of the nasal and nonnasal symptoms of allergic rhinoconjunctivitis, while also showing a subjective improvement in the quality of life and in overall clinical impression. For chronic urticaria the symptoms (itching and the development of papules) lessens from the second day of treatment onwards, in a similar way to other antihistamines used as comparators. Bilastine should not be administered at meal times to avoid interference with the absorption process. It is not distributed to the central nervous system, is scarcely metabolized, and elimination is through the kidneys and feces, with a 14-hour elimination half-life. It has no effect on cytochrome P450. During clinical development, bilastine was shown to be a drug that is adequately tolerated, with a similar effect to placebo with regard to drowsiness and changes in heart rate. In relation to its use, headaches were the most frequent adverse effect to be reported. No cardiotoxic effects have been observed, and the therapeutic dose does not alter the state of alertness

Termoterapia transpupilar en neovascularización subretiniana oculta secundaria a degeneración macular asociada a la edad. Primeros resultados

To determine the efficacy of transpupillary thermotherapy (TTT) to treat choroidal neovascularization (CNV) in patients with age-related macular degeneration (ARMD). Patients and Methods: Eight patients (ten eyes) with occult CNV were treated by TTT. A 810 nm diode laser was used to perform TTT. The diode laser was delivered through a panfunduscopic contact lens. Results: Three eyes showed a visual acuity improvement and a decrease in exudation on fluorescein angiography. Four eyes remained stable. Nevertheless, lesions worsened after treatment in three cases. One of these cases suffered an overtreatment. Conclusions: TTT may be a useful therapy in some cases of CNV in patients with age-related macular degeneration. Randomized and multicentric studies are necessary to stablish precise indications of this therap

Randomized crossover pharmacokinetic evaluation of subcutaneous versus intravenous granisetron in cancer patients treated with platinum-based chemotherapy

BACKGROUND: 5-HT3-receptor antagonists are one of the mainstays of antiemetic treatment, and they are administered either i.v. or orally. Nevertheless, sometimes neither administration route is feasible, such as in patients unable to admit oral intake managed in an outpatient setting. Our objective was to evaluate the bioavailability of s.c. granisetron. PATIENTS AND METHODS: Patients receiving platinum-based chemotherapy were randomized to receive 3 mg of granisetron either s.c. or i.v. in a crossover manner during two cycles. Blood and urine samples were collected after each cycle. Pharmacokinetic parameters observed with each administration route were compared by analysis of variance. RESULTS: From May to November 2005, 31 patients were included and 25 were evaluable. Subcutaneous granisetron resulted in a 27% higher area under the concentration-time curve for 0-12 hours (AUC(0-12h)) and higher levels at 12 hours, with similar values for AUC(0-24h). The maximum concentration was lower with the s.c. than with the i.v. route and was observed 30 minutes following s.c. administration. CONCLUSION: Granisetron administered s.c. achieves complete bioavailability. This is the first study that shows that s.c. granisetron might be a valid alternative to i.v. delivery. Further trials to confirm clinical equivalence are warranted. This new route of administration might be especially relevant for outpatient management of emesis in cancer patients

Randomized pharmacokinetic study comparing subcutaneous and intravenous palonosetron in cancer patients treated with platinum based chemotherapy

BACKGROUND: Palonosetron is a potent second generation 5- hydroxytryptamine-3 selective antagonist which can be administered by either intravenous (IV) or oral routes, but subcutaneous (SC) administration of palonosetron has never been studied, even though it could have useful clinical applications. In this study, we evaluate the bioavailability of SC palonosetron. PATIENTS AND METHODS: Patients treated with platinum-based chemotherapy were randomized to receive SC or IV palonosetron, followed by the alternative route in a crossover manner, during the first two cycles of chemotherapy. Blood samples were collected at baseline and 10, 15, 30, 45, 60, 90 minutes and 2, 3, 4, 6, 8, 12 and 24 h after palonosetron administration. Urine was collected during 12 hours following palonosetron. We compared pharmacokinetic parameters including AUC0-24h, t1/2, and Cmax observed with each route of administration by analysis of variance (ANOVA). RESULTS: From October 2009 to July 2010, 25 evaluable patients were included. AUC0-24h for IV and SC palonosetron were respectively 14.1 and 12.7 ng × h/ml (p = 0.160). Bioavalability of SC palonosetron was 118% (95% IC: 69-168). Cmax was lower with SC than with IV route and was reached 15 minutes following SC administration. CONCLUSIONS: Palonosetron bioavailability was similar when administered by either SC or IV route. This new route of administration might be specially useful for outpatient management of emesis and for administration of oral chemotherapy