The government may incorporate a clause for DNA mapping of human volunteers involved in drug trials in the revised Schedule -Y of the Drugs & Cosmetics Act, it is learnt. The move is in line with the need for upgrading the clinical research regulations to global standards as pharmacogenetics is gaining in importance in the accuracy of drug research.

The sources in the Central Drugs Standard Control Organisation (CDSCO) said that as certain drugs even after toxicity and pre-clinical studies shows adverse results in certain human volunteers during clinical trials, the research oriented pharma companies along with various drug control agencies around the world are moving towards introducing DNA mapping of human volunteers involved in clinical trials.

According to top drug experts, the co-existence of genetic polymorphisms in drug metabolizing enzymes, targets, receptors, and transporters, in the context of drug and non-drug influences may result in high frequencies of unusual drug reaction phenotypes. Hence, it is possible that a drug that has successfully completed phase 1 and 2 trials may cause serious side effects in certain volunteers if the subjects' genetic characters differ.

It may also prove that the common parameters may not work in drug trails involving human subjects with the generally accepted criterion. So the modern studies, especially after the developments genomic science, it is recommended to be more specific on the trial subjects in genetic way rather than depending on the conventional parameters. This new approach would take care of the protection of volunteers as well as the accuracy of trial results, opined Dr Venkateswarlu, deputy drug controller (India), West.

The US FDA has already initiated the respective directives to make genetic identification of human subjects for drug trials to ensure the optimum efficacy rate of the drug.

The global drug experts are of the view that concept of perfect man is only idealistic and practically all the human beings carry a significant number of DNA glitches.

Researches show that any two people are about 99.9 per cent identical at the genetic level. It's the 0.1 per cent difference that scientists expect will provide clues about common diseases as well as helps predict drug responsiveness and drug adverse events.

US FDA recently quoted Dr. Francis Collins, head of NIH's National Human Genome Research Institute, as "many of these differences are simple substitutions in the genetic code. These substitutions of genetic letters are called single nucleotide polymorphisms or SNPs. The human genome is thought to contain at least 10 million SNPs, but most of them are medically insignificant."

DNA is made up of four chemicals, called bases. Trying to map four variations at 10 million points is impractical. Because genetic variation among individuals is organized in "DNA neighborhoods" called haplotype blocks, Dr. Collins says his institute's latest big international collaborative project to map genetic variation is very practical. Scientists will only need to detect a few tag SNPs to identify a haplotype block. He predicts the HapMap project will be able to define all the common haplotypes in the human genome in two years. Then studies associating diseases or drug responses can be done with a "haplotype tag" set of about 250,000 SNPs.

The HapMap of a group of people known to respond to a drug could be compared to the HapMaps of those who don't respond or have adverse reactions to it. If enough of these associations can be made, scientists could zero in on specific genetic variations. Even without knowing specific genes, however, HapMap information could help select patients for clinical trials and tailor treatment to improve on drug efficacy rates and reduce adverse events, he says in a document published by the official website of the US FDA.