Which of the following is incorrect with reference to drug abuse?

The correct option is: "Nicotine is a very effective sedative and pain killer."

To understand why this option is the incorrect statement (and therefore the correct answer to the question), let us analyze the scientific facts associated with each option step-by-step:

1. Analysis of Nicotine (The Correct Answer):
Nicotine is an alkaloid found in tobacco. Rather than acting as a sedative or a painkiller, nicotine is a potent stimulant. It stimulates the adrenal glands to release adrenaline and noradrenaline into the blood circulation, both of which raise blood pressure and increase heart rate.
In medical practice, very effective sedatives and painkillers (analgesics) are typically opioids like morphine and heroin, not nicotine. Therefore, stating that nicotine is a very effective sedative and painkiller is factually incorrect.

2. Analysis of the other options (which are factually correct statements):

• Cannabinoids affect the cardiovascular system of the body: This is a correct statement. Cannabinoids are known to interact with receptors in the body that produce cardiovascular effects, such as increased heart rate and alterations in blood pressure.
• Heroin is extracted from the latex of Papaver somniferum: This is a correct statement. Heroin (diacetylmorphine) is chemically synthesized from morphine, which is extracted directly from the latex of the poppy plant, Papaver somniferum.
• Excessive dosage of coca alkaloid causes hallucinations: This is a correct statement. Coca alkaloid (cocaine) interferes with the transport of the neurotransmitter dopamine. In excessive doses, it acts as a potent central nervous system stimulant and can cause severe hallucinations.

Since the question asks for the incorrect statement with reference to drug abuse, the statement about nicotine being a sedative and painkiller is the right choice.