Selamectin is a topical

Topical

In medicine, a topical medication is applied to body surfaces such as the skin or mucous membranes such as the vagina, anus, throat, eyes and ears.Many topical medications are epicutaneous, meaning that they are applied directly to the skin...

 parasiticide and antihelminthic used on dogs and cats, distributed by Pfizer

Pfizer

Pfizer, Inc. is an American multinational pharmaceutical corporation. The company is based in New York City, New York with its research headquarters in Groton, Connecticut, United States...

. It prevents heartworms, flea

Flea

Flea is the common name for insects of the order Siphonaptera which are wingless insects with mouthparts adapted for piercing skin and sucking blood...

s, ear mite

Ear mite

Ear mites are mites that live in the ears of animals. The most commonly seen species is Otodectes cynotis .-Contagion:...

s, sarcoptic mange (scabies), and certain types of ticks in dogs, and prevents heartworms, fleas, ear mites, hookworm

Hookworm

The hookworm is a parasitic nematode that lives in the small intestine of its host, which may be a mammal such as a dog, cat, or human. Two species of hookworms commonly infect humans, Ancylostoma duodenale and Necator americanus. A. duodenale predominates in the Middle East, North Africa, India...

s, and roundworms

Nematode

The nematodes or roundworms are the most diverse phylum of pseudocoelomates, and one of the most diverse of all animals. Nematode species are very difficult to distinguish; over 28,000 have been described, of which over 16,000 are parasitic. It has been estimated that the total number of nematode...

 in cats. Selamectin is not approved for human use.

Usage

Selamectin is generally prescribed for cats and smaller indoor dogs due to studies that have shown it does not work as well to prevent heartworms as some of the oral preventatives.

The drug is applied topically. It is waterfast, and does not lose its effectiveness with bathing. It is packaged according to its varying dosage sizes, and is applied once monthly.

Mode of action

Selamectin disables parasites

Parasitism

Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host. Traditionally parasite referred to organisms with lifestages that needed more than one host . These are now called macroparasites...

 by replacing glutamate in their muscle

Muscle

Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...

 synapses

Chemical synapse

Chemical synapses are specialized junctions through which neurons signal to each other and to non-neuronal cells such as those in muscles or glands. Chemical synapses allow neurons to form circuits within the central nervous system. They are crucial to the biological computations that underlie...

; glutamate is the amino acid

Amino acid

Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...

 which normally interacts with the receptors

Receptor (biochemistry)

In biochemistry, a receptor is a molecule found on the surface of a cell, which receives specific chemical signals from neighbouring cells or the wider environment within an organism...

 that open chloride channels into the muscle. Selamectin interferes with this process; it activates the chloride current without desensitization, allowing chloride ions to enter the nerve cells

Neuron

A neuron is an electrically excitable cell that processes and transmits information by electrical and chemical signaling. Chemical signaling occurs via synapses, specialized connections with other cells. Neurons connect to each other to form networks. Neurons are the core components of the nervous...

 and causing neuromuscular paralysis

Paralysis

Paralysis is loss of muscle function for one or more muscles. Paralysis can be accompanied by a loss of feeling in the affected area if there is sensory damage as well as motor. A study conducted by the Christopher & Dana Reeve Foundation, suggests that about 1 in 50 people have been diagnosed...

, impaired muscular contraction, and eventual death.

The substance fights both internal and surface parasitic infection

Infection

An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...

. Absorbed into the body through the skin and hair follicles, it travels through the bloodstream, intestines, and sebaceous glands; parasites ingest the drug when they feed on the animal's blood.

Side effects

Selamectin has been found to be safe and effective in a 2003 review.

Selamectin has high safety ratings, with less than 1% of pets displaying side effects

Adverse effect

In medicine, an adverse effect is a harmful and undesired effect resulting from a medication or other intervention such as surgery.An adverse effect may be termed a "side effect", when judged to be secondary to a main or therapeutic effect. If it results from an unsuitable or incorrect dosage or...

. In cases where side effects do occur, they most often include passing irritation or hair loss at the application site. Symptoms beyond these (such as drooling, rapid breathing, lack of coordination, vomiting, or diarrhea) could indicate the existence of a serious underlying cause, requiring immediate veterinary care.

Similar products

Main rival products for dogs include ivermectin (trade names Stromectol, Ivermec and others) or milbemycin oxime

Milbemycin oxime

Milbemycin oxime is a veterinary drug from the group of milbemycins, used as a broad spectrum antiparasitic. It is active against worms , insects and mites ....

 (Interceptor) for heartworms, fipronil

Fipronil

Fipronil is a broad spectrum insecticide that disrupts the insect central nervous system by blocking the passage of chloride ions through the GABA receptor and glutamate-gated chloride channels, components of the central nervous system. This causes hyperexcitation of contaminated insects' nerves...

 (Frontline) or lufenuron

Lufenuron

Lufenuron is the active ingredient in the veterinary flea control medication Program, and one of the active ingredients in the veterinary flea control, heartworm prevention, and anthelmintic medicine milbemycin oxime/lufenuron .Lufenuron is stored in the animal's body fat and transferred to adult...

 (Program) for fleas, or the combination milbemycin oxime/lufenuron (Sentinel) for both.