As many as four people died in just 48 hours as a wave of opioid overdoses has swept through communities in middle Georgia, health officials said earlier this week.

» RELATED: Georgia overdose deaths jump as opioid crisis deepens: Interactive map

Toxicology reports are not back yet in the cases in Bibb County, so it’s unclear what exactly the drug is, but overdoses have been on the rise as the country suffers from an opioid crisis.

The pharmacological effects of opiates, derived from the opium poppy, have been known for at least 6,000 years. The process was further refined over time into stronger and stronger substances as well as synthetic versions.

Many of the compounds, like morphine, became indispensable for their ability to let people withstand painful medical procedures. But the drugs are powerfully addicting, and people can become dependent on opioids that legitimately serve medical purposes as well as those that don’t.

These short explanations from information provided by the Drug Enforcement Administration and National Institute on Drug Abuse shows how the drug type evolved to become ever more potent.

An opioid is a term for a variety of substances similar to natural opium alkaloids.

The drug dulls the senses and relieves pain. Morphine, heroin and fentanyl are all opioids. Other examples include pharmaceuticals like OxyContin, Vicodin, codeine and methadone.

Heroin is an illicit drug with no legitimate medical use in the United States. Morphine and fentanyl are both licit opioids used during medical procedures and often prescribed by doctors to control pain. Fentanyl, however, is manufactured in clandestine labs and mixed with heroin or sold alone as a heroin substitute.

Opioids can be swallowed, smoked, sniffed, or injected. Users are prone to become psychologically and physically dependent on opioids.

» RELATED: Authorities testing counterfeit pills blamed for wave of overdoses

Morphine is a naturally occurring substance extracted from the seedpod of the Asian opium poppy plant, Papavar somniferum. The principal constituent of opium, it is one of the most effective drugs at relieving severe pain.

Opium is made by drying the milky resin that seeps from incisions made in unripe seedpods. An alternate method of harvesting morphine is to extract alkaloids from the mature dried plant stalks, to produce a fine brownish powder.

Street names: Dreamer, Emsel, First Line, God’s Drug, Hows, M.S., Mister Blue, Morf, Morpho, and Unkie

Gelatin capsules are seen filled with heroin at the Montgomery County Crime Lab. Staff photo by Chris Stewart

Credit: Chris Stewart

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Credit: Chris Stewart

Heroin is a highly addictive drug and the most rapidly acting opiate.

It is synthesized from morphine, the naturally occurring substance extracted from the seed pod of the poppy plant. Heroin usually appears as a white or brown powder or as a black sticky substance, known as “black tar heroin.”

Heroin, two to four times as potent as morphine, works much faster because it’s less soluble in water, and more soluble in oils and fats, than morphine. Once in the bloodstream it can pass rapidly through the blood-brain barrier that normally prevents the passage of water-soluble and large molecules. As a result, it is much more potent than morphine, but its effect does not last as long.

The majority of heroin sold in the U. S. originates from Southeast Asia, South America and Mexico. Low purity Mexican black tar heroin is most common on the West Coast, while high purity Colombian heroin dominates in the East and most Midwestern states.

Street names: Big H, Black Tar, Chiva, Hell Dust, Horse, Negra, Smack, and Thunder

In October, Dayton Fire Department medics prepare to transport an overdose patient who was revived with Narcan to a hospital emergency department. Montgomery County residents were treated for overdoses more than 2,200 times during 2016. CHRIS STEWART / STAFF
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Fentanyl is a synthetic opioid 100 times more powerful than morphine and 30-50 times more powerful than heroin.

It was first introduced as an intravenous anesthetic under the trade name Sublimaze in the 1960s. It is often sold as heroin to the unsuspecting user.

Licit pharmaceutical fentanyl products include lozenges, tablets and transdermal patches as well as injectable forms. Fentanyl is often used for pain management in cancer patients as well as analgesic and anesthetic for patients undergoing surgery.

Once less prominent in the illicit drug trade, fentanyl has overtaken heroin locally as the substance responsible for the most overdose deaths.

Street names: Apache, China Girl, China White, Dance Fever, Friend, Goodfella, Jackpot, Murder 8, TNT, as well as Tango and Cash

Brooke Ehlers, technical leader of the Miami Valley Regional Crime Laboratory's Chemistry Section, tests a drug sample for fentanyl. The highly potent synthetic opioid -- often cut with heroin or used alone -- has been on the streets for more than a year in the Dayton area and is responsible for an increasing number of overdose deaths. CHRIS STEWART / STAFF

Credit: Chris Stewart

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Credit: Chris Stewart

Carfentanil is also a synthetic opioid 100 times stronger than even fentanyl and 10,000 times more powerful than morphine.

Its primary legitimate purpose is a tranquilizer for large animals like elephants. Carfentanil has been linked to a significant number of overdose deaths nationwide, including fatalities in Montgomery County.

A small amount of carfentanil no larger than a grain of salt can kill. In July, Ohio Attorney General Mike DeWine warned police agencies across the state against handling or field testing street drugs that could contain dangerous levels of fentanyl or carfentanil.

In September, The Drug Enforcement Administration (DEA) issued a nationwide warning about the health and safety risks of carfentanil that can also resemble powdered cocaine.