Though not any active role to play, excipients are most crucial in the design and delivery of a drug. They normally stay inert acting as medium for the active drug substance. However, excipients have been undergoing tremendous transformations these days redefining the conventional modes of drug design.
For one, the increasing fascination towards direct compression (DC) excipients. DC excipients are slowly taking over the traditional ones.
Rapidly disintegrating tablets and capsules worked on DC platform have become popular among the medical fraternity.
The DC method involves the compression of a dry blend of powders that comprises drugs and various excipients. The simplicity and cost-effectiveness of the direct-compression process have positioned direct compression as an attractive alternative to traditional granulation technologies.
The direct-compression process is directly influenced by the properties of the excipients. The physicomechanical properties of excipients that ensure a robust and successful process are good flowability, good compressibility, low or no moisture sensitivity, low lubricant sensitivity, and good machineability even in high-speed tableting machinery with reduced dwell times.
Currently, a number of DC grade excipients have replaced their traditional counterparts in formulations manufacturing. The major DC excipient, which hit the market, is DC grade of lactose that costs about Rs 70/kg in Indian market, higher than that of normal lactose (Rs 40/kg). As the normal lactose contain 5 per cent of water, the DC grade lactose with lesser water content is found more suitable for the moisture sensitive drugs. It avoids the binding of granules, and increases the stability of drugs.
In India, a quantity of 6000 mt lactose is sold annually. Till 4 years back, the MNCs from Holland and New Zealand were the producers of lactose. But today the scenario has changed as the Indian companies-Cepham India and Dynamics -dominate the lactose market.
The story of dicalcium phosphate, a substitute of lactose, is not different. Its price stood at Rs 18-20 per kg. Since the price is low, it is found a wider use in place of lactose. It is manufactured totally in India and there were no import at all. The DC grade of dicalcium phosphate is available at market now, according to the industry sources.
The US and Western European markets for specialty excipients for oral-solid-dosage-form pharmaceuticals are highly competitive and are together valued at upward of $800 million in 2003.As the excipient market dilates, the various technologies also foray the industry.
The readymix excipients are the another new trend in drug manufacturing. Instead of using various excipients separately, such potpourri of excipients are widely used for convenience. The mix for tablet coating is found a broader use in the industry. Tabcoat of Pharmaceutical Coating Pvt Ltd is one of the readymix film coatings available in India.
Contrary to earlier days, the number of new excipients arrive the market. The arrival of new excipients. Earlier, the number of excipients available in the market was very few like lactose, dicalcium phosphate, starch, sodium carboxy methyl cellulose (CMC) etc. Today, excipients like hydroxypropyl methylcellulose (HPMC), protanol, protacid, xanthan gum, titanium dioxide, polyvinylpyrrolidone providone K-30 (PVP K-30), micrcrystalline cellulose (MCC) etc are new ones. Protanal and protacid of FMC- Holland are alginates and alginic acid respectively, which are hydrocolloids of vegetable origin occurring in marine brown algae. MCC, a white, odourless, tasteless powder, is used as a binder in prescription medications and is included in over-the-counter pain relievers and cough/cold remedies.
Carbomer, an excipient used in gels, is also a newly-launched one. It improves the consistency of gel. Earlier, the paraffin-based gels melts as soon as it was applied on skin. But the carbomer excipient avoids such disadvantages. Carbopol and acrypol are the brand names of carbomer excipients.
The rising number of new excipients is found as the offshoot of growing pressure on formulators to search for new excipients to achieve the desired set of functionalities.
"As the new functions of drugs increase regularly, the manufactures are forced to launch new excipients which comply with the corresponding functions," Dr Sanjay M Sanghavi of Medi Pharma, a leading dealer of excipients said on citing the reason for increasing number of newly-launched excipients.
"Always the excipient market is dependent on the pharmaceutical industry, so even the ripples in the pharma industry also affects the excipient market and it can't go alone," he added.
Meantime, the Chinese dragon, which grabs each and every segment of pharmaceutical arena, does not spare the excipient market. The price of PVP-K 30 of Chinese producers is $ 7/kg while that of BSAF stood at $10/kg. HPMC, produced by Dow and ShinEtsu costs around $12/kg while HPMC from China prices at $ 8/kg when it forayed the market four years back. Now it costs $ 6.5 kg.
"Naturally, as the rates of Chinese excipients are low, it will be much-sought-after ones for the drug manufactures who are not bothered about the quality," says Ashok Shah of Uma Brothers, another leading excipient dealer. But nowadays, the quality of Chinese excipients has been increasing, he added.
Increasing regulatory pressure on purity, safety, and standardization of the excipients has catalyzed the formation of an international body, the International Pharmaceutical Excipients Council (IPEC). IPEC has made efforts to harmonize requirements for purity and functionality testing.