Introduction
Anti-arrhythmic drugs that are used to treat abnormal heart rhythms due to irregular electrical activity of the heart. These disturbances can lead to alternations in overall cardiac functions that may be life-threatening. These drugs can be classified into four categories:1, 2, 3
Class I Sodium channel blockers
Class II Beta Blockers
Class III Potassium channel blockers
Class IV Calcium channel blockers
Sodium channel blockers
These drugs bind and block the fast sodium channels that are responsible for the rapid depolarization. It reduces the velocity of action potential transmission within the heart. For example, quinidine, procainamide, etc.3
Beta-blockers
These drugs reduce the blood pressure by blocking the effects of the hormone epinephrine. It causes the heart to beat more slowly and with the less force which in turns lower the blood pressure. For example, Nadolol, propranolol, etc.3
Potassium channel blockers
These drugs act as inhibition of potassium efflux through the cell membrane. It is used to improve the motor function in patients with multiple sclerosis. For example, sotalol, amiodarone, etc.3
Calcium channel blockers
These drugs are used to lower blood pressure by slowing the activity of calcium into heart and blood vessels which in turn make it easier for the heart to pump. It also controls chest pain and irregular heartbeats. For example, Verapamil, etc.3
These approaches are designed to help the person think differently, change their expectations and behaviours. We have tried to set out standard procedures for screening/spot test for anti-arrhythmic drugs. which are easily available and useful for the forensic science laboratory. This article covers the spot test/colour test of Acebutolol, Ajmaline, Alprenolol, Amiodarone, Hydoquinidine, Lidocaine, Mexiletine, Nadolol, Oxprenolol, Prajmalium Bitartrate, Procainamide, Pindolol, Quinidine, Timolol and Verapamil.4, 5, 6, 7, 8
Test of Anti-arrhythmic Drugs
Acebutolol
Sulphuric acid test
Few drops of the extract are taken on a white tile or test tube.
Few drops of sulphuric acid are added to it.
The yellow colour is observed which indicates the presence of acebutolol.9
Ajmaline
Mandelin test
Two ml of extract is taken in a test tube.
Few drops of mandelin’s reagent are added to it.$
Red colour is observed which indicates the presence of ajmalin.10
Marquis test
Two ml of extract is taken in test tube.
Few drops of marquis reagent are added to it.
Violet colour is observed which indicates the presence of ajmaline.11
Alprenolol
Marquis test
Two ml of extract is taken in a test tube.
Few drops of marquis reagent are added to it.$
Red colour is observed which indicates the presence of alprenolol.10
Liebermann’s test
Two ml of extract is taken in a test tube.
Few drops of Liebermann’s reagent are added to it.$
Red colour is observed which indicates the presence of alprenolol.9
Hydroquinidine
Thalleioquin test
Few drops of the extract are taken on a filter paper.
One to two drop of thalleioquin reagent is added to it.
Green colour is observed which indicates the presence of hydroquinidine.11
Mexiletine
Marquis test
Two ml of extract is taken in a test tube.
Few drops of marquis reagent are added to it.$
Red colour is observed which indicates the presence of mexiletine.12
Nadolol
Nessler’s test
Two to three drops of the extract are taken in a porcelain basin.
Two to three drops of Nessler's reagent is added to it.
The mixture is agitated & heated to 100℃ in a water bath.
Brown colour is observed which indicates the presence of nadolol.10
Oxprenolol
Mandelin test
1. Two ml of extract is taken in a test tube.
2. Few drops of mandelin’s reagent are added to it.
3. Play of colour from grey to violet colour is observed which indicates the presence of oxprenolol.
Prajmalium Bitartrate
Liebermann’s test
Two ml of extract is taken in a test tube.
Few drops of Liebermann’s reagent are added to it.
Black colour is observed which indicates the presence of Prajmalium Bitartrate.9
Procainamide
Ninhydrin test
The residue is extracted in methanol.
One drop of extracted residue is taken on filter paper.
One drop of ninhydrin reagent is added to it.
Paper is air-dried in hot air.
Yellow colour is observed which indicates the presence of procainamide.10
Sotalol
Mercurous nitrate test
The extract is taken in powdered form in a test tube.
Few drops of Mercurous nitrate are added.
Few drops of ethanol are added to it.
Black colour is observed indicates the presence of sotalol.12
Preparation of Solutions(9-12)
Coniferyl alcohol reagent: 0.1 g of coniferyl alcohol is warmed until it melt, dissolve in 3 ml of ethanol and diluted to 10 ml with water.
Liebermann’s reagent: 1 gm of sodium or potassium nitrite is dissolved in 10 ml of sulphuric acid with cooling and swirling to absorb the brown fumes.
Mandelin’s reagent: 1 g of ammonium vanadate is dissolved in 1.5 ml of water and dilute to 100 ml with concentrated sulphuric acid.
Marquis reagent: 100 ml of concentrated sulphuric acid is mixed with 1 ml of formaldehyde solution.
Nessler’s reagent:
Ninhydrin: 0.5 g of ninhydrin is dissolved in 40 ml of acetone.
p-Dimethyl amino benzaldehyde: 1 g of p-Dimethyl amino benzaldehyde is dissolved in 100 ml of ethanol. The solution is acidified with 10 ml of dilute hydrochloric acid.
Mercurous nitrate: 10 ml of a saturated solution of mercurous nitrate is added to 20 mg of Sodium bicarbonate.
Conclusion
In analysis of any poison, screening/spot test is especially useful for knowing the presence of the anti-arrhythmic drugs which can be confirmed by the more confirmatory tests. It saves time for the toxicologist, by helping them in ruling out the probability of poisons which can be confirmed by the more confirmatory tests and gives a quick clue to the doctors for patient management in emergency poisoning cases. The result of the analytical methods depends on the amount and purity of the sample extracted. Screening/spot test has been developed after repeated trial and testing. The techniques are being improved every time. It is important for the forensic toxicologists to know the best available method and help to detect the poison in criminal investigations.