Taking vitamin A supplements can weaken the bones and increase the risk of fractures up to seven times, according to a large Swedish study. The latest study is the first to measure levels of the vitamin in blood, rather than just asking about diet and supplement use. The three-decade study and other evidence suggest that daily vitamin A consumption of more than 1.5 milligrams can be dangerous, and that most people should not take vitamin A supplements.
Current dietary recommendations call for only 0.7 mg of vitamin A for women and 0.9 mg for men a day. That is easily supplied by a healthy diet. But many popular multivitamins contain 0.75 mg to 1.5 mg of vitamin A, generally listed on labels as 2,500 international units and 5,000 IUs, respectively. “Vitamin A is potentially harmful,'' said Dr. Donald Louria, chairman emeritus of preventive medicine at the University of Medicine and Dentistry of New Jersey in Newark, N.J. “Unless there is a known medical reason like certain diseases of the eye, people should not be taking vitamin A supplements.''
Vitamin A is known as an antioxidant. Antioxidants are believed to reduce the risk of cancer and heart disease. Government studies show one-third to one-half of Americans take vitamin A or multivitamins containing it. Vitamin A can interfere with cells that produce new bone, stimulate cells that break down old bone and interfere with vitamin D, which helps the body maintain normal calcium levels. But multivitamins containing 0.1 mg or less of vitamin A are fine for people eating a healthy die
Lack of new drugs is reaching crisis point, says review
The number of new drugs approved in the United States last year fell to half the annual average over the past five years. Only 15 new drugs were approved by the Food and Drug Administration (FDA) in 2002,compared with a five year annual average of 31 says an editorial in Nature Reviews: Drug Discovery (2003:2:3).
It warns that the fall in the number of new drugs is reaching crisis point and says that new drug applications are down worldwide. It warns that most so called blockbuster drugs were not forecast to be big sellers. The initial sales forecast for tamoxifen, it points out, was a modest $160000;"To select a proposed research target, a range of issues needs to be evaluated.
The first, and perhaps most important, is what constitutes an improved medicine. Many descriptors of varying utility are used to describe new medicines. "The current favourite is `blockbuster drug,' which is much used by stock analysts to indicate annual sales in excess of US $1 billion." The point is not to criticise those who prepare sales forecasts, but to emphasise the inherently unpredictable nature of sales forecasting, particularly for truly innovative medicines."
Gene therapy trials halted by FDA
The U.S. Food and Drug Administration (FDA) said it was halting about 30 gene therapy trials after learning that a second child in a French gene therapy experiment has leukemia. The two boys in France were diagnosed with leukemia after receiving the experimental treatment for "bubble boy disease" -- X-linked severe combined immunodeficiency, or SCID. The gene therapy, which reinforces the children's bone marrow with genetically engineered immune cells, had worked remarkably well in the children. They had seemingly been cured of SCID before the leukemia symptoms began and were among 10 gene therapy patients in France who were living normal lives.
After the first boy in France was diagnosed with leukemia in September 2002 the FDA suspended three similar gene therapy trials that had started or were about to start in the United States. British regulators declined to suspend similar experiments there. The FDA had started a review of 150 gene therapy trials that used a retrovirus as a vector .So far the review found no evidence anyone in a U.S. gene therapy trial had developed cancer.
Implants to monitor organ functioning
Data recorders in airplanes, the so-called black boxes, describe what went wrong after a disaster. Now, medical devices are emerging to act like a black box in the human body, except they're being used to prevent disaster. Though still in an early stage, a market is growing for implantable monitors, tiny devices that track the function of a person's organs. Five years ago, Medtronic Inc. released its first implantable monitor for people with mysterious fainting spells.
Two product generations later, Medtronic has sold more than 25,000 of the 2-inch-long monitors, which weigh just a few grams. They're placed in a person's pectoral muscle, sometimes for just a few days, and track heart activity in a 42-minute loop. Other implants are being readied to monitor blood pressure and heart rate — even inside the heart itself. The advance of wireless technology and the Internet allowed makers of other implants, such as pacemakers and defibrillators, to add monitoring features.
Medtronic and rival Biotronik Inc. in the past year began selling such products. Data Sciences International Inc., a small company near Medtronic's headquarters in this Minneapolis suburb, will start clinical trials next year of monitors that can track blood pressure inside the heart itself. The company, which produced implantable monitors in lab animals, is racing with Medtronic to produce devices aimed at heart failure patients. Discovery to lead to New Generation fertility drugs and contraceptives
A protein that allows human embryos to implant in the womb has been identified. This could lead to the development of a new generation of fertility drugs and contraceptives. Research in the US has revealed that L-selectin, which forms on the embryo surface six days after fertilization, works as a biological 'glue' to anchor the embryo to the womb lining. The discovery has important implications for reproductive medicine because implantation problems are among the most common causes of infertility. A drug that stimulated the production of L-selectin could potentially help thousands of sterile couples to have children. Drugs to block its production could be used as an alternative method of birth control to the morning-after pills.
Transdermal drug delivery technology
The essence of developing alternative drug delivery technologies is to increase drug delivery efficiency, safety and patient convenience. Substantial research has been conducted for the past several years to develop technologies that meet the requisite criteria for delivering the drug through a non-invasive route. Promising technologies like pulmonary and transdermal have branched out from the rest and have made significant strides. Although, these technologies are susceptible to certain challenges, there are attendant overwhelming benefits.
Transdermal drug delivery utilizes the skin for the delivery of the drug molecules from the surface of the skin, through its layers, to the circulatory system. Although, all drugs, particularly the ones with high molecular weight cannot be delivered through the transdermal route, there exists a huge potential for this technology.
The first transdermal patch was introduced in 1981. Subsequently, the applications of transdermal drug delivery have been expanded to include more products in multiple therapeutic areas. The hormone replacement therapy patches dominate the transdermal market. Products such as testosterone, nicotine, nitroglycerine, and analgesics are also available as transdermal patches.
Alza is a pioneer in this technology and was responsible for developing the first transdermal patch in the U.S. The company has developed number of leading brands such as Duragesic, Estraderm, Transderm-Nitro, Transderm-Scop, and Catapress-TTS. Transdermal patches are also available as OTC, which include Nicotine patches, and patches for pain relief and for treating cold, sinus etc.
The technology for the transdermal systems is now being broadened to include more drugs, specially the biotechnology drugs. The molecules of proteins or peptides are too large to enable them to pass through skin by using existing patch technology, so researchers are investigating patches powered by electricity or ultrasound.
The first E-Trans product, fentanyl, is in Phase III development, and is designed to alleviate acute post-operative pain. Imarx is developing ultrasound assisted transdermal insulin system. Buspirone patch being developed by Elan holds tremendous potential in the transdermal drug delivery market. Alprostadil, minoxidil, hormones, analgesics, contraceptives, and antifungal are some of the other potential products in development.
Four day treatment of fosmidomycin effective against malaria
A new antimalarial, fosmidomycin, was safe and effective in a preliminary study reported in the December issue of The Lancet. In vitro, this drug showed great promise in treating multidrug resistant strains. Fosmidomycin is an antibiotic that inhibits a key enzyme produced by Plasmodium falciparum, and which suppresses the growth of multidrug-resistant strains in vitro. In the open-label study of malaria patients in Gabon, nine patients received the drug for five days, eight patients were treated for four days, and 10 patients were treated for three days at doses of 1.2 g every eight hours.
In all three groups, the drug was well-tolerated, and parasite elimination and fever reduction were rapid. After two weeks, cure rates were 89 per cent for the five-day regimen, 88 per cent for the four-day regimen, and 60 per cent for the three-day regimen. The authors warn against extrapolating these results to larger numbers of patients, and point out that the significant increase in gametocyte carriers after treatment has the potential to enhance transmission. "Further studies on combinations of fosmidomycin with other antimalarial drugs are needed to assess its safety and efficacy in children and to boost efficacy while benefiting from a shorter and simpler treatment regimen".
Inexpensive and fast route production of human antibodies
Also called immunoglobulins, antibodies are proteins produced by immune cells that are designed to recognize a wide range of foreign pathogens and target antigens- (proteins, carbohydrate molecules) and other pieces of the pathogen--specific to that foreign invader. They also alert the immune system to the presence of the invaders and attract lethal "effector" immune cells to the site of infection. Antibodies can also be useful as therapeutics for a number of human diseases ranging from rheumatoid arthritis to leukemia. Likewise, there are many other human proteins that could potentially be used as drugs.
Algae may offer a cheaper and easier way to produce these proteins. Since algae grow naturally and use carbon dioxide from the air as a carbon source and sunlight as an energy source, whole ponds--tens of thousands of liters--of the algae can be grown once they are modified to produce the protein of interest. Modifying the algae to produce proteins entails inserting a gene into the genome of the chloroplast, the organelles within the alga cell that converts sunlight and carbon dioxide into plant matter. The algae then express and assemble the antibodies within the chloroplasts, which can later be purified, intact. Now that the researchers have established the fundamental technology, they are looking at applying it to any number of proteins and receptors.
Compiled from WWW by Dr. Venkat Appaji Padmanabhuni
email : appajipv@hotmail.com