IHS Chemical Week

CHEM IDEAS

Is Continuous Processing in Pharma's Future?

2:35 PM MDT | August 7, 2012 | By GIRISH MALHOTRA

The answer to the question is: It depends. This are not the answer one would expect from anyone who is a proponent of continuous processing. Indeed, “it depends” needs further explanation. I describe pharmaceutical manufacturing processes as follows:
 
            API (drug) + Formulation processing/packaging = Dispensable drug dose
 
We all know that each component and the resulting product must—must—meet the established performance and quality standards. Annual volume, process design, and equipment are some of the factors that direct us to the right process selection.

Table 1 (below) illustrates the amounts of API (active pharmaceutical ingredient) needed for various dosages to serve variable population size. This table directs us to the answer to the “May be and depends” question between batch and continuous processing in pharmaceutical manufacturing. Breaking down the overall manufacturing process described above assists in rationalization.

 
Between API manufacture and formulation/packaging later has the highest potential to be a continuous process. This observation is based on the annual volume of tablets needed. It is expected that the formulation and packaging process steps are adequately designed. Quality by Design (QbD) will be the rule for such processes.
 
To serve 10 million people using 0.1-mg tablets, API volume is not large enough to have a continuous process. If the equipment used to produce the APIs is going to stay the same as those currently used, less than optimum processes will stay in place. Since the companies with the most current manufacturing practices are able to achieve their profit margins, they do not have any incentives to change their manufacturing practices, even if the methods are inefficient and highly unsustainable. Such operations present an excellent opportunity to improve yield, create sustainable processes, lower manufacturing costs, and improve profitability.
 
For continuous processing to become a reality for APIs while still using the current equipment technologies, production volumes have to be about 750,000 lbs/year, or higher, per site, or the size of the equipment has to change to produce for lower volumes—i.e. a complete shift is needed. A single plant operating continuously producing 750,000 lbs/year would produce about 110 pounds of product per hour. Such plants, if they become a reality, could significantly reduce the regulatory load and would produce the highest quality product.
 
To serve 10 million people taking 0.1-mg tablet/day/year, 3.65 billion tablets would be needed. This figure means producing about 8500 tablets per minute (80% operating rate) from a single manufacturing train. A single, continuous train that takes the API to a finished tablet is very feasible, provided the equipment is properly designed. Depending on the size of the tablet, commercially available equipment can produce up to one-million tablets per hour. Through campaigns, this particular train could also be used to produce other drugs following cGMP practices. Multiple tableting and packaging trains can be used to fulfill higher tablet needs.
 
As dose and frequency needs increase, the needed API volume increases and manufacturing trends towards continuous processes. Increased per-site production volume and process technologies can justify better manufacturing methods that have higher yields and are sustainable. It is possible that the companies might still use batch processing even if the total API production volume could justify continuous manufacturing. This can happen if the companies do not want to invest in better process technologies. If the companies do not change their methods, competition will force the change.
 
Based on the above review one can conclude that better than 70%–80% of the APIs needed would be produced by batch process using existing type of reactors, heat exchangers, and other processing equipment unless the existing equipment can be used creatively to develop continuous processes. This is definitely possible. On the other hand, better than 85%–95% of the formulations can be produced using continuous processes.
 
The above quick review demystifies the "it depends” mystery and shows us a clear path. The choice to act is ours.
Table 1

Dose

Milligram

Tablets

per day

Doses

per year

Population,

Millions

Tablets/yr.

Millions (1)

 

Tablet Process

API needed,
 Kg./ yr.

 

API Process

 

 

 

 

 

Batch

Continuous

 

Batch

Continuous

 

 

 

 

 

Number of plants

 

Number of plants

0.1

1

365

  10

     3,650

*

**

456

1

No

0.1

1

365

100

   36,500

*

**

4,563

1

No

0.5

1

365

500

 182,500

*

**

114,063

1

**

10

1

365

100

   36,500

*

**

456,250

*

**

10

1

365

500

 182,500

*

**

2,281,125

*

1-2

50

1

365

 10

     3,650

*

**

228,125

*

**

250

1

365

500

 182,500

*

**

57,031,250

*

5-7

500

1

365

500

 182,500

*

**

114,062,500

*

10-14

* Multiple batch plants would be needed to meet the global demand.  

** Potential continuous process.

(1) 80% formulation and packaging yield. 














 
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