A maid who feared she was about to be scolded slipped a tranquilliser into the breakfast of her employer's wife and daughter in the hope they would "calm down", a court heard.

Indian national Gurpreet Kaur, 31, got hold of a risperidone pill - which had been prescribed to her 74-year-old employer to treat his bipolar disorder - and put it in the women's oatmeal, leaving them "temporarily impaired".

Yesterday, Kaur was jailed for eight months after pleading guilty to one count each of administering and attempting to administer risperidone to her employer's Singaporean wife, Madam Chander Kanta Harbans Lal, 72. One count of administering the drug to Ms Anita Kumari Premnath, 47, was considered during sentencing.

Deputy Public Prosecutor Esther Wong said risperidone is a tranquilliser used to treat schizophrenia and moderate to severe manic episodes associated with bipolar disorders. It is also a stupefying drug known to induce drowsiness.

The court heard Kaur was hired in January last year to cook and do chores at the Ghim Moh flat. Kaur had learnt of the pill's effects after talking to employer Premnath Shivadial's wife, and decided to use it in May last year. The offences came to light when Ms Anita spotted her placing additional items into a pot of oats. She approached the maid and saw two tablets inside it. Ms Anita told her family about the incident and her niece alerted the police. Medical tests found traces of risperidone in the women's blood and urine.

DPP Wong called on District Judge Kessler Soh to jail Kaur for nine months, saying she targeted a vulnerable victim in her own home.

Judge Soh told Kaur: "What you did was very wrong and could potentially cause serious harm."