PART-IX-CNS STIMULANTS-COFFEE AND SMOKING

CENTRAL STIMULANTS-COFFEE &SMOKING

CNS stimulants are drugs inducing increased motor activities, excitement, and decrease the feelings of tiredness.

1.METHYLXANTHINES

1.Caffeine

2.Theophylline

3.Theobromine

Theobromine is of little interest and it is mostly found in cocoa butter.

These drugs stimulate the CNS by a series of chemical and biological pathways involving an increase in cyclic guanosine monophosphate and cyclic adenosine monophosphate the two nucleotides which are increasing intracellular signaling to exhibit an increased motor activity and thereby stimulating the CNS.

Caffeine:-

 

The pharmacodynamical effects of caffeine are as follows:-

1. Centrally caffeine increases motor activity and alertness.

2.Heart and Bloodvessels-Caffeine increases heart rate (+chronotrophic) and contractility (+inotrophic)

3. Caffeine and its derivatives relax the smooth muscles of the bronchioles and dilate them to facilitate good ventilation. Hence drinking a cup of coffee would be beneficial during an attack of cold and asthma.

4. Caffeine is a weak diuretic and increases the excretion of sodium+,potassium+, and chloride-ions in the urine. Hence over a drink of coffee may lead to heavy loss of these ions.

5. Caffeine stimulates gastric secretions and thereby enhance acidity in the stomach. Hence care should be taken by those who suffer from peptic ulcers to avoid coffee drinks.

Side Effects

1.Insomnia

2.Agitation

3.Nausea and Vomiting

4.Convulsions

5.Cardiac Arrhythmias

Theophylline

 

Theophylline is already dealt with in detail in the post describes Asthma in this blog. Please refer to it.

2.NICOTINE

 

Physiology

Nicotine is having double action on the preganglionic receptors. Because of its specific actions at the preganglionic receptors the receptors are known as nicotinic receptors.

At low dosage it causes ganglionic stimulation by depolarization through acetylcholine. At high doses it causes ganglionic blockade.

At low dosage it causes arousal, relaxation, and improved attention through ganglionic stimulation.

At high doses it causes respiratory depression through medullary suppression through the ganglionic blockade.

Pharmacology

At Low Dose

Nicotine at a low dosage increases heart rate. constricting the blood vessels and thereby elevate B.P.

At High Dose:-

1. At a high dose, it slows the heart rate, dilates the blood vessels and thereby lower the B.P.

2. It causes many dysfunctions in our digestive system.

Nicotine increases acid secretions in the stomach and causes peptic and duodenum ulcers by impairing the secretions of sodium bicarbonate from the pancreas. 

Nicotine increases the stomach's susceptibility to H.pylori.

Nicotine weakens L.E.S.and thereby causes heartburn and G.E.R.D.

Nicotine causes the liver's ability to metabolize various toxic wastes and drugs ingested.

Nicotine causes Crohn's disease.

3. Nicotine causes severe urinary incontinence.

All the above effects are due to the ganglionic blockade of nicotine at high doses.

Clinical Uses

Fortunately nicotine has no therapeutic uses.

Kinetics

Nicotine is rapidly absorbed through the buccal mucosa, by inhalation, and by the skin.

Side Effects

1.Irritability

2.Tremors

3.Intestinal cramps

3.Diarrhea

4.Increased heart rate and B.P.

Withdrawal Symptoms For Addicts

1.Craving

2.Irritability

3.Restlessness

4.Anxiety

5.Stomach pain.