Inviato: Lun 02 Gen, 2006 18:01 Oggetto: In futuro...
1: Drugs R D. 2005;6(6):345-69. Related Articles, Links
Analysis of lipid peroxidation and electron microscopic survey of maturation stages during human cataractogenesis: pharmacokinetic assay of Can-C N-acetylcarnosine prodrug lubricant eye drops for cataract prevention.
Morphological and biophysical techniques described in this study have shown that membrane derangement occurs in human cataractous lenses. The data suggest that these disruptions were globules, vacuoles, multilamellar membranes and clusters of highly undulating membranes. Deleterious structural damage of the lens fibre cell plasma membranes serve as the primary light-scattering centres that cause the observed lens opacity. Nuclear cataract, a major cause of loss of lens transparency in the aging human, has been thought to be associated with oxidative damage, particularly at the site of the nuclear plasma membrane. Phospholipid molecules modified by oxygen accumulate in the lipid bilayer, change its geometry and impair lipid-lipid and protein-lipid interactions in lenticular fibre membranes. Lipid peroxidation (LPO) is a causative and pathogenic factor in cataract. Increased concentrations of primary molecular LPO products (diene conjugates, lipid hydroperoxides, oxy-derivatives of phospholipid fatty acids) and end-fluorescent LPO products have been detected in the lipid moieties of aqueous humour samples and human lenses obtained from patients with senile and complicated cataracts as compared with normal donors. In the present study, a rapid and simple high-performance liquid chromatographic (HPLC) assay for determination of imidazole-containing dipeptides in the aqueous humour of the eye was developed. The method was applied to determine the pharmacokinetic parameters and the time-course of N-acetylcarnosine and L-carnosine-related product in the eye, following a single dosage of topical ocular administration of peptide. Utilising data from pharmacokinetic studies and the specific purity of the N-acetylcarnosine (NAC) ingredient as a source of the pharmacological principle L-carnosine, we have created an ophthalmic time-release prodrug form including the US FDA-approved carboxymethylcellulose lubricant and other essential ingredients (Can-C, private label Nu-Eyes). This formulation increases the intraocular absorption of L-carnosine in the aqueous humour and optimises its specific antioxidant activity in vivo while reducing the toxic effects of lipid peroxides on the crystalline lens. L-carnosine that enters the aqueous humour can accumulate in the lens tissue for a reasonable period of time. The presence of L-carnosine in transparent crystalline lenses during normal aging was detected and its concentration in this case was about 25 microM. At different stages of cataract development, the level of L-carnosine drastically decreased, reaching about 5 microM in ripe human cataracts. However, administration of pure L-carnosine (1% solution) to the rabbit eye (instillation or subconjunctival injection) does not lead to accumulation of this natural compound in the aqueous humour at the time level over 30 minutes at a concentration exceeding that in placebo-treated matched eyes, and its effective concentration is exhausted more rapidly. Use of NAC prodrug eye drops optimises the clinical effects of L-carnosine in the treatment of ophthalmic disorders (such as prevention and reversal of cataracts in human and animal [canine] eyes). The data provided predict a clinical effect with NAC ophthalmic prodrug, and show that the magnitude and duration of this effect are directly related to the bioavailability of L-carnosine released from NAC in the aqueous humour of the anterior eye segment. The ophthalmic NAC drug shows promise in the treatment of a range of ophthalmic disorders that have a component of oxidative stress in their pathogenesis (including cataract, glaucoma, dry eye, vitreous floaters, inflammatory disorders, and corneal, retinal and systemic diseases [such as diabetes mellitus and its ophthalmic complications]). There is a need for further and better collaboration between Innovative Vision Products' cataract control and ophthalmic services, improved education of people affected by cataract, a commitment that N-acetylcarnosine eye drops will be the preferred treatment before orthodox cataract surgery is attempted, and consideration of outcomes and a possible role of the NAC drug cataract treatment as source of referral for orthodox surgical, ophthalmic and optometric services.
Registrato: 05/09/05 19:05 Messaggi: 322 Località: Verona (province of Verona)
Inviato: Gio 05 Gen, 2006 22:45 Oggetto:
Mamma mia Vitto78, ormai sei diventato il mago dell'NCBI!!!!!! Non ho parole, veramente. Bravo, ti dico questo sinceramente, apprezzo quello che fai, bravo!
Confrontato al tuo, il mio impegno in questo momento sembra nullo, sono in una fase di depressione cavolo
Andrea 25 (VR) _________________ Chi capisce che ciò che basta è abbastanza ne avrà sempre a sufficienza! (^_*)
(Ragazzo di Verona)
alcuni ptenziali effetti collaterali delle iniezioni intravitreali:
OSN SuperSite Top Story 10/19/2006
Surgeon: Be prepared to manage complications of intravitreal therapies
NEW YORK — As intravitreal therapies for retinal diseases proliferate, surgeons should be prepared to manage complications associated with these new drugs and delivery methods, according to a surgeon speaking here.
"Intravitreal therapy is incredibly explosive right now," said Thomas B. Connor Jr., MD. "We are in a position to do things we have not been able to do before and deliver medications to a level we have not yet been able to achieve."
Dr. Connor discussed potential complications of intravitreal drug therapy in a presentation at the OSN New York Symposium.
Although these new therapies show great potential for treatment of age-related macular degeneration and other pathologies, unwanted effects related to intravitreal injection of drugs can arise. Endophthalmitis and retinal detachment are the complications of intravitreal drug injection that retinal surgeons are "scared of the most," Dr. Connor said. Other adverse events can include hemorrhage, lens injury from injection needles and IOP elevation, all of which the surgeon should be prepared to manage, he said.
"There also may be potential systemic side effects," he said. "It is just a concern right now, but something to monitor for."
Dr. Connor reviewed safety guidelines for avoiding these complications after intravitreal injections. He recommended avoiding excessive lid manipulation, marking the injection site, using adequate anesthesia and stabilizing the injection to avoid reflux.
"Most important, educate the patient about what to look out for, such as redness and new floaters, and tell them to give you a call," he said.
Research yielding new horizons for intraocular therapies, surgeon says
CANCUN, Mexico — Intraocular therapies are set to become more common for a variety of ocular diseases as researchers continue investigating the potential of intraocular drug delivery, such as intracorneal bevacizumab injections, according to an ophthalmologist speaking here.
"I am very enthusiastic about local treatment," said Rubens Belfort Jr., MD, PhD, in giving the Gradle Lecture at the Pan-American Association of Ophthalmology meeting. "There is a lot to be done, and many things that can be discovered and used on behalf of the patients."
According to Dr. Belfort, steroids have been an important experimental breakthrough for treating such diseases as uveitis, vasculitis and scleritis, as well as during high-risk operations.
Additionally, the scope of diseases that steroids may be used for continues to increase as studies show such drugs can be safely injected intraocularly, Dr. Belfort said. For example, experimental drugs such as Retaane (anecortave acetate, Alcon) may be used to treat neovascularization without increasing IOP, he said.
In addition to the development of intraocular drugs, drug delivery implants, such as those designed to break down into water and carbon dioxide, are being studied for their safety and efficacy in humans, Dr. Belfort said.
Similar to the significant evolution of IOLs over time, applications for drug delivery implants are only just beginning to be realized and such implants may take on vastly advanced forms in the coming years.
The potential indications for using bevacizumab (Avastin, Genentech) are also expanding. The drug is currently being investigated for treating corneal neovascularization and has shown efficacy for decreasing the number of new vessels. However, it is still unclear whether the drug can cause adverse events such as corneal melting, Dr. Belfort said.
"We have to be very careful," he said.
As these new implants and therapies continue to take shape, Dr. Belfort closed his talk with a message to young ophthalmologists: "It is very important that young people do not get the idea that everything is known," he said. "We need more young people to get well-trained in basic and clinical research. Only the well-trained will be able to develop better medicine."
un recente studio molto incoraggiante sulla diffusione delle iniezioni intravitreali per il trattamento delle patologie oculari. nell'ultimo anno per il quale sono disponibili statistiche (2006) si è registrato negli stati uniti del 111%. speriamo che prima o poi si trovi qualcosa anche per le miodesopsie!!
OSN SuperSite Breaking News 1/21/2008
Rapid rise in the use of intravitreal injections is 'the engine that will eat ophthalmology'
WAIKOLOA, Hawaii — Intravitreal injections increased exponentially in 2006, becoming the fastest growing procedure in ophthalmology, a speaker here said.
Kevin J. Corcoran, COE, CPC, FNAO, OSN Practice Management section member, presented CMS data from 2006 showing intravitreal injections ranked third among ophthalmic procedures. He said it underwent "exponential growth" over the course of 5 years, making it the fastest growing procedure in all of Medicare.
"You're looking at the engine that will eat ophthalmology," Mr. Corcoran said. "This one is the biggest thing on the planet and nothing is growing this fast — nothing."said.
Cataract surgery with IOL implantation still ranked No. 1 with YAG capsulotomy coming in second, but intravitreal injections grew by 111% in 1 year, outpacing all other procedures, he said. Most of the other procedures that increased were lacrimal procedures, he said. Complex cataract surgery also increased 25%, he said.
"Intravitreal injection is now No. 3. It certainly wasn't No. 3 last year," Mr. Corcoran said. "This one is on its way to becoming No. 1 in a real big way."
The CMS data showed that, in 2006, there were more than 500,000 procedures performed in the United States through Medicare. Out of every 100 eye exams performed there were 2.4 intravitreal injections administered, he showed.
Conversely, photodynamic therapy, laser choroid and focal laser decreased by 61%, 30% and 9%, respectively.
"Those are the ones that, formerly, you did for the same reasons, so clearly a huge shift in retina," Mr. Corcoran said.
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