FOUR men were jailed on Wednesday for selling illegal medicinal products mainly in the red-light areas off Jalan Besar last year.

Three of them had in their possession the illegal sexual enhancement drug Power 1 Walnut pills, which made news early this year when the banned drug caused severe reactions in many men, who had to be hospitalised.

Khoo Teck Chye, 38, was given eight months' jail after pleading guilty to five charges of having products containing sildenafil - used for treating male erectile dysfunction - for sale at the backlane of Desker Road on Sept 4 last year. He had earlier been fined for offences under the Poisons Act.

Three others - Tan Koh Heng, 53, Chong Kee Siong, 58, and Tan Chiew Hee, 51 - were each jailed six months. They all pleaded guilty last week to between five and seven charges.

All four had other charges considered during their sentencing.

Among the seven charges proceeded against Tan Koh Heng was one of peddling 432 Power 1 Walnut tablets at a makeshift stall at the backlane of Rowell Road on Sept 4.

He said he bought some of his medicines from an elderly man who used to run the stall and some from unknown Chinese nationals peddling medicines nearby.

Officers raided Tan Chiew Hee's provision shop at Flanders Square off Petain Road on Oct 25 and found assorted medicines displayed on the racks.

Health Sciences Authority prosecutor Ngoo Chih Min pressed the court to impose a sufficiently deterrent sentence on the four.

Between Jan 29 and March 24, 18 persons were found either unconscious at home or with severe and life-threatening symptoms of very low blood sugar after taking Power 1 Walnut, he said.

There were 47 suspected cases of adverse drug reactions to the same drug.

The four could have been fined up to $5,000 or jailed for up to two years each, or both on each charge.