FORMER president Rodrigo Duterte has dared President Ferdinand Marcos Jr. to undergo a drug test with him at Luneta Park in Manila as he insisted that the Chief Executive is a drug addict.

Duterte issued the statement a day after Marcos blamed fentanyl for his predecessor's accusations in an expletive-filled speech in Davao City last Sunday.

The Palace has not issued a statement as of press time.

Former president Rodrigo Duterte File Photo

In a press conference in Davao City, Duterte said he was prescribed a fentanyl patch eight years ago after he underwent surgery due to a motorcycle accident.

"It is prescribed by the doctor, and I got my fentanyl drug prescription at Saint Luke's pain center, and I recall that Dr. Javier prescribed it to me. I'm giving you the name of my doctor. After that, I got well, Mr. President," Duterte said.

"I didn't take fentanyl anymore because I don't need it. Now, why are you attacking me? Does cocaine have a prescription? Where do you get your supply?" he asked.

Duterte, father of Vice President Sara Duterte, then challenged Marcos to undergo a drug test with an independent body at Luneta Park.

"It is not me who will prove. I didn't run for public office. It is an accusation against him from the public. Why do I need to prove," Duterte said when asked if he had any proof that Marcos was taking illegal drugs.

Speaking in English and Filipino, Duterte invited Marcos to "sit at the Luneta Park with him and take a blood test from an independent entity or doctor."

Duterte also insisted that Marcos was on the watchlist of the Philippine Drug Enforcement Agency (PDEA), a claim already denied by the drug agency.

The former president said he would release it to the public when he gets his hands on the document.

He slammed PDEA for being "fools" for claiming that it does not have a record. "Who in PDEA would volunteer for the narco list?" Duterte asked.

Duterte said he would look for the document. "As soon as it is in my hands, I will release it," he said.

The former president made the statement after Marcos' cousin, Speaker Ferdinand Martin Romualdez, dared him to prove through evidence his accusation that the President was a drug user.

During a prayer rally in Davao City Sunday, Duterte called Marcos in Filipino as being "high on illegal drugs," accused him of being a drug addict and warned that the administration was against amending the Constitution to "perpetuate themselves in power."

Marcos laughed off the accusation, saying it must be the effect of fentanyl, a drug Duterte has admitted taking during his term as president.

"I think it's the fentanyl. Fentanyl is the strongest painkiller that you can buy. It is highly addictive, and it has very serious side effects, and PRRD (President Rodrigo Roa Duterte) has been taking the drug for a very long time now," Marcos said.

"When was the last time he told us that he was taking fentanyl? About five, six years ago, something like that. After five, six years, it has to affect him, so I think that's the reason he acted that way. So, you know, I hope his doctors take better care of him. They should not allow this problem to persist," he added.

Pressed if he was categorically denying that he was involved in illegal drugs, Marcos laughed and replied: "I won't even dignify that question."

On its website, the US Drug Enforcement Administration said fentanyl is a potent synthetic opioid drug approved by the Food and Drug Administration for use as an analgesic or pain relief and anesthetic.

According to the agency, fentanyl is approximately 100 times more potent than morphine and 50 times more potent than heroin as an analgesic.

Fentanyl overdose can cause stupor, changes in pupil size, clammy skin, cyanosis, coma and respiratory failure leading to death, the drug enforcement agency said.

When he was president, Duterte admitted to using fentanyl because it made him feel better.

In one of his speeches, Duterte said his doctor had advised him to stop using the drug because he might lose his cognitive ability.

The 78-year-old former president also disclosed in 2018 that his partner, a former nurse, had warned him that fentanyl could turn him into an addict.