What Is Polymyxin B Sulfate API?

Brief Info

Polymyxin B Sulfate Chemical Structure

Polymyxin B Sulfate API is a white to off-white powder derived from the bacterium Bacillus polymyxa.

It is one of the key ingredients for dermal ointments along with Bacitracin powder, Zinc Bacitracin powder, and Triamcinolone acetonide.

Polymyxin B is easily soluble in water (50mg/mL) and stable in acidic solutions

It is almost insoluble in organic solvents such as ethers, ketones, esters, hydrocarbons, etc.

For example, its solubility in ethanol is 0.115 mg/mL.

But it is a very hygroscopic chemical so you may want to handle it quickly to avoid leeching moisture from the air while repacking.

When it is dissolved in solvents, its neutral solution can be placed at room temperature for a week without affecting its potency, while its alkaline solution is unstable and it will disintegrate very quickly.

There are two types of Polymyxins: Polymyxin B and Polymyxin E(also known as colistin).

Polymyxin B is composed of polymyxins B1, B1-I, B2, B3, and B6.

Polymyxins B1 and B2 are considered the major components within the compound.

These related components are structurally identical except for a different fatty acid group on each fraction.

Results from in vitro studies have shown that there are marginal differences in MIC data when comparing the fractions.

What Is Polymyxin B Sulfate Used For?

Polymyxin B Sulfate API is made into ophthalmic ointment with Neomycin sulfate and bacitracin zinc

Polymyxin B is a cationic basic peptide that acts as a detergent.

It can be used for urinary tract infections and meningitis as it exerts bactericidal effects against almost all Gram-negative bacilli except the Proteus and Neisseria genera.

The main mechanism of Polymyxin B’s Bactericidal Effects is something like this: it will bind to the cell membrane of the bacteria and alter their membrane structures, making the cell more permeable.

As a result, the following water uptake leads to cell death of the bacteria.

#1. Usages

Polymyxin B is an antibiotic against gram-negative bacilli, with bactericidal functions.

It has a strong antibacterial effect on most gram-negative bacilli.

It also very effective on Pseudomonas aeruginosa, E. coli, salmonella, dysentery bacillus, influenza bacillus, pertussis bacillus, gas-producing bacillus and pneumonia bacillus.

However, proteus amoebae are not sensitive to this product. Polymyxin B is effective against bacteria in both growth and stationary phases.

In the past, it was mainly used clinically to treat gram-negative bacterial infections, especially those caused by Pseudomonas aeruginosa and Escherichia coli, such as respiratory infections, peritonitis, bile duct infections, urinary tract infections, burn infections, ocular and corneal infections, and sepsis.

Gradually, it has been replaced by other antibiotics with better efficacy and lower toxicity.

But it can still be used topically for infections of the eye, ear, skin, and mucous membrane and Pseudomonas aeruginosa burns caused by sensitive bacteria.

#2. Mechanism of action

Its bactericidal working mechanism is to change the permeability of bacterial cells.

As a polypeptide antibiotic, Polymyxin B has extensive surface activity on bacterial cells.

Because it contains lipophilic functional groups (positively charged free amino groups), which can introduce lipoproteins, combine with phosphate in the cell membrane phospholipids, and change the composition of the cytoplasmic membrane synthesized by bacteria, to increase the surface area of the cell membrane.

Then it will ruin the original shielding function of the cytoplasmic membrane and make the membrane much more permeable, resulting in the leakage of a large number of intracellular components, and finally causing the bacteria to die.

What is even better is that bacteria are less likely to develop resistance to polymyxin B.

What Are Polymyxin B Dosage Forms?

polymyxin b sulfate is made into ointments with bacitracin zinc and neomycin sulfate

Dosages are as below:

Powder for injection

Ear drops


Eye drops over the counter


lyophilized powder for solution

It is also made into first kits and topical ointments combined with other ingredients such as combining bacitracin, bacitracin zinc, neomycin sulfate, lidocaine HCl, etc.

What Is The HS Code Of Polymyxin B Sulfate API?

You can tell from its chemical structure that Polymyxin B sulfate belongs to the class of organic compounds known as polypeptides.

These are peptides containing ten or more amino acid residues.

But it is also an antibiotic. In China, it is classified as Other Antibiotics with HS Code 2941909099 with supper class as Antibiotics.

How Much Does Polymyxin B Sulfate API Cost?

The price of pharma-grade topical type by commercial order quantities is about 3500~4500 USD/kg as Fob Shanghai/Beijing.

The price above is for the micronized powder suitable for manufacturing powder spray and ointment.

The price for plain powder should be lower and the EXW price is around 3600 USD per kg.

There is also injection-grade powder available in the market, which has higher purity with strict sterilization.

The cost for injection-grade powder is over 6000 USD per kg.

For more accurate prices, please contact us directly.

You can also check its export and import prices from PharmaCompass below:

polymyxin b sulfate prices from pharmacompass

As you can see its import and export prices are around 5300 USD per kg for quantities of 100 kilos.

So far as we know, 5300 USD per kg is a high price compared to the cost in 2021.

With the increasing manufacturing capacity from Chinese factories, the unit price per kilo has been brought down to 3200 USD in the middle of 2021.

However, the price for injection-grade polymyxin b is much higher, it may cost twice the topical grade.

This 3500 USD-per-kilo price is also the mainstream market price within Asia, and make sure you do not pay 6000 for 1 kilo before you order.

How To Store and Ship Polymyxin B Sulfate API?

#1. Storage

For long-term storage, polymyxin B sulfate powder as small samples should be stored under dark conditions at 2-8°C. 

During our stability tests at room temperature, after three years of storage, we did not observe any change in the appearance of the samples. (Well sealed and protected from moisture and light)

If it is already dissolved into solutions, and the solution should be filtered for sterilization and stored at 2-8°C. The solution is stable at 37°C for 5 days.

#2. Shipping

Polymyxin B has been tested by our authorities and proved to be a safe and common chemical to be shipped by air.

It is not poisonous. Check its acute toxicity data below:

Mice oral LD50: 790 mg/kg

mice abdominal LD50: 20500 ug/kg; 

mice subcutaneous LD50: 59500 ug/kg;

mice venous LD50: 5400 ug/kg;

puppy intracerebral LDLo: 320 ug/kg;

guinea pig subcutaneous LD50: 58 mg/kg.

It is not flammable, explosive, or oxidative, so it won’t cause any fires or explosions if you handle it properly. Therefore, there is no need for special packing materials.

Common plastic bags and cartons are ok for packing.

So you can ship it by air, by courier or by sea, totally up to you and your order quantity.

If you are worried about the possible potency loss, you can add ice bags during transportation.

But our stability has shown that it is ok for stability if you ship it without any ice.

Many customers have proved this point with their years of orders in the past.


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