Piperonyl butoxide

Absorption

Piperonyl butoxide is applied topically. In a study evaluating the 7-day urinary accumulation of piperonyl butoxide after topical application, it was found that approximately 2% of the dose was absorbed through the skin. The percutaneous absorption when applied to the scalp was found to be 8.3%.

Toxicity

The acute oral LD50 for rats is 4,570 to 12,800 mg/kg and 2,700 to 5,300 mg/kg for rabbits. It is low to very low in toxicity when ingested by mammals.

Description

Piperonyl butoxide (PBO) is a water insoluble colorless to pale yellow liquid that was developed in the 1940s to increase the effectiveness of various pesticides. It is currently registered as an active ingredient in more than 1500 products used for indoor or outdoor pesticides, including agricultural maintenance of some food crops.

Chemical properties

Piperonyl butoxide (PB) is a Light Yellow Liquid. It has no smell or a faint smell and a slightly bitter taste. It does not dissolve in water but can be dissolved in mineral oil and most organic solvents. It is stable to light, resistant to hydrolysis, and is not corrosive. In terms of toxicity, the LD50 (lethal dose for 50% of a test population) is 7500mg/kg in rats when administered orally.

The Uses of Piperonyl butoxide

Piperonyl butoxide is used as a synergist for pyrethrins and their synthetic analogues.

Background

Piperonyl butoxide (PBO) is an organic compound used as a component of pesticide formulations. It is used for the treatment of head, pubic (crab), and body lice. Piperonyl butoxide is a synergist. It has no pesticidal activity of its own, but acts to increase the activity of pesticides such as carbamates, pyrethrins, pyrethroids, and rotenone. Piperonyl butoxide is a semisynthetic derivative of safrole.

Indications

For the treatment of head, pubic (crab), and body lice.

What are the applications of Application

Piperonyl Butoxide is An insecticide synergist

Definition

ChEBI: Piperonyl butoxide is a member of benzodioxoles. It has a role as a pesticide synergist.

Preparation

First, safrole is obtained from allyl chloride and methylenedioxybenzene. Then, piperonyl butoxide is produced by catalytic hydrogenation, chloromethylation, and etherification reactions.

General Description

Pale yellow to light brown liquid with a mild odor and a faint bitter taste.

Air & Water Reactions

Insoluble in water.

Reactivity Profile

Piperonyl butoxide can react with oxidizing materials.

Fire Hazard

Piperonyl butoxide is combustible.

Agricultural Uses

Insecticide synergist: A U.S. EPA restricted Use Pesticide (RUP). Not listed for use in EU countries. Piperonyl butoxide is a synergist, i.e., not a pesticide itself, but enhances the properties of other chemicals. It is used with other pesticides such as pyrethrins, pyrethroids, rotenone and carbamates in food and non-food agricultural products, home and garden products, termite and mosquito products, and veterinary pesticide products. It inhibits the insect’s ability to break down an insecticide before it takes effect, thereby prolonging the action, and reduces the necessity for using a stronger formulation.

Trade name

Trade names have included Butoxide, Butacide, Butocide, and Pyrenone (mixture with allethrin).

Pharmacokinetics

Piperonyl butoxide does not affect the mixed-function oxidase system in humans. In small trials in human volunteers, usual doses of piperonyl butoxide had no effect on humans.

Safety Profile

Poison by skin contact. Moderately toxic by ingestion and intraperitoneal routes. An experimental teratogen. Experimental reproductive effects. Many glycol ether compounds have dangerous human reproductive effects, Questionable carcinogen with experimental tumorigenic data. Mutation data reported. Combustible when exposed to heat or flame; can react with oxidizing materials. To fight fire, use foam, CO2, dry chemical. When heated to decomDosition it emits PLATINOL 0 cis-PLATlNUM(II) DIAMMINE- DICHLORIDE

Environmental Fate

PBO is rapidly degraded (half-life 8 h) in the environment by photolysis and is metabolized by soil microorganisms. Its estimated atmospheric half-life is approximately 3 h.

Metabolic pathway

Piperonyl butoxide is used primarily in admixture with pyrethrins and some of the pyrethroids to enhance and prolong their insecticidal action. Much of this use is in domestic and industrial situations. Metabolism studies were conducted soon after its discovery and first use in the 1950s and 1960s. The main impetus initially was to understand the mode of action as a synergist. When this was shown to be due to the inhibition of oxidative metabolism, further studies were conducted to address possible toxic interactions with other pesticides and drugs in man.
Piperonyl butoxide undergoes rapid photodegradation and microbial degradation in soil. It is also rapidly metabolised in insects and mammals by oxidative attack at the methylenedioxy carbon atom and in the side chain. A comprehensive review by Casida (1970) describes the chemistry, mode of action and metabolism of piperonyl butoxide and several related methylenedioxyphenyl compounds. Though published nearly 30 years ago, the review remains a very useful compilation of a large amount of information, supported by more than 300 references.

Metabolism

Piperonyl butoxide is minimally absorbed in humans. Metabolism has not been studied.

Degradation

Piperonyl butoxide is stable to hydrolysis at pH 5,7 and 9 in sterile buffers in the dark at 25 °C. It is rapidly degraded in aqueous solution at pH 7 in sunlight with a DT₅₀ of 8.4 hours (PM). The compound was found to be relatively stable under a variety of irradiation conditions as a thin film on glass or in organic solvent (methanol, benzene and cyclohexane). Loss of the butoxyethoxy side chain was observed to give 5-methyl-6-propyl-l,3- benzodioxole (2), butoxyethanol (3) and ethanediol (4) (Fishbein and Gaibel, 1970). These studies did not utilise radiolabelled compound. The partial pathways are shown in Scheme 1.

Toxicity evaluation

Piperonyl butoxide has low to very low toxicity in birds.Researchers consider piperonyl butoxide moderately toxic to fish，although it is unlikely to accumulate.Some aquatic invertebrates may be highly sensitive to this compound.
As a synergist, PBO inhibits mixed-function oxidases, including cytochrome P450, and resistance-associated esterases that allow insects to degrade an insecticide, allowing enhanced insecticide efficacy. It does not effectively act as a synergist in mammals.