Pharmacology and Toxicology Phenolphthalein can be used for the treatment of habitual refractory constipation, mainly acting on the colon. After oral administration, it can be subject to slowly decomposition under the effect of the small intestinal alkaline fluid to form soluble sodium salt, thereby stimulating the plexus inside the intestinal wall.
It directly acts on the intestinal smooth muscle and increase peristalsis, while also inhibiting the absorption of water within the intestine, so that water and electrolyte accumulates in the colon, resulting in laxative effect.
It has mild effect and rarely causes intestinal cramps. The absorbed drugs mainly exist in the form of glucuronide to be excreted from urine or the feces, some can also be excreted to the intestine through the bile, reabsorbed in the intestine, to form intestinal - liver circulation and prolong the role time.
At 4 to 8 hours after the drug administration, the patients will discharge soft stool. The excretion time for drug administration once needs 3 to 4 days.
This product can also be secreted from milk. Adverse reactions Phenolphthalein mainly takes effect in the large intestine, leading to the formation of little amount of semi-liquid feces in 4 to 8 hours without colic.
The claim regarding that the yellow phenolphthalein is three times stronger than the white version has not been proven. As a result of enterohepatic circulation, the effect of a single dose can last 3 to 4 days.
This drug is an active member in a lot of laxative preparations that can be legally sold without a doctor's prescription. Severe adverse effects are rare but can occur in excess amount. For the elderly, phenolphthalein should be hanged, because its lasting effect can cause serious depletion of water and electrolytes.
In allergic patients, it can cause occur dermatitis fixed rash, itching, burning sensation, blistering, and residual pigmentation. There are reports of fatal allergic reactions, but have not yet determined to be related with phenolphthalein.
There are occasional reports of non-thrombocytopenic purpura and the occurrence of dehydration and electrolyte imbalance caused excessive diarrhea after long-term application. Phenolphthalein makes alkaline urine or feces turn pink. Application This product is a commonly used acid indicator with the range of color change between pH 8. Phenolphthalein is also a drug, can be used as a laxative, acting on the colon for the treatment of constipation.
Used as an acid-base indicator; as irritant laxative for the treatment of constipation Production method It is derived from the condensation of phthalic anhydride and phenol. Chemical Properties white to light yellow crystal powde Uses anthelmintic Uses Used as indicator for acidimetric titrations. Definition An acid—base indicator that is colorless in acid solutions and becomes red if the pH rises above the transition range of 8—9.
Definition phenolphthalein: A dye used as anacid-base indicator. It is colourlessbelow pH 8 and red above pH 9. Itis used in titrations involving weakacids and strong bases. It is also usedas a laxative. World Health Organization WHO Phenolphthalein has been widely used as a laxative since its cathartic activity was first described in Because it undergoes enterohepatic circulation it is eliminated slowly and it has been associated with adverse effects, notably skin reactions, potassium loss and atonia.
This has led to the withdrawal of phenolphthalein from pharmaceutical preparations in several countries. Elsewhere, it remains available, often in over-the-counter preparations.
Safety Profile Confirmed carcinogen. US Food and Drug Administration recommends removal from laxative formulations. Moderately toxic by intraperitoneal route. Human systemic effects: changes in urine composition, gastritis, nausea or vomiting. Used in medicine as a laxative; in chemistry as an indicator. When heated to decomposition it emits acrid smoke and irritating fumes Carcinogenicity Phenolphthalein is reasonably anticipated to be a human carcinogen based on sufficient evidence of carcinogenicity from studies in experimental animals.
Related articles Toxic Effects of Phenolphthalein Phenolphthalein is a chemical compound, often used as an indicator in titrations and its formula is C20H14O4. It is a weak aci If you use phenolphthalein, you would titrate until it just becomes colourless at pH 8.
On the other hand, using methyl orange, you would titrate until there is the very first trace of orange in the solution…. Because it changes color at the pKa of a mid strength acid, it is usually used in titration for acids.
Unlike a universal indicator, methyl orange does not have a full spectrum of color change, but it has a sharp end point. Methyl Orange is a weak acid which dissociates in water forming orange neutral molecules. Under acidic conditions, the equilibrium is to the left, and the concentration of the neutral molecules is too low for the orange colour to be observed. Methyl orange is a pH indicator frequently used in titrations because of its clear and distinct colour change.
Because it changes colour at the pH of a midstrength acid, it is usually used in titrations for acids. Methyl orange shows red colour in acidic medium and yellow colour in basic medium. Phenolphthalein is a weak organic acid. In acid base titration phenolphthalein is used as indicator. Therefore, the correct answer is option B. Phenolphthalein turns color because the molecule undergoes a rearrangement in structure that turns the colorless molecule into a colored ion.
In slightly acidic solutions to neutral solutions, the phenolphthalein molecule is very poorly soluble in water, and is typically dissolved in alcohol due to its low solubility. Phenolphthalein is a presumptive test that reacts with the heme molecule present in blood.
A positive reaction gives a pink color. The swab in the image below shows the characteristic color of a positive reaction with the phenolphthalein test, indicating the presence of blood. The compound remains colorless throughout the range of acidic pH levels but begins to turn pink at a pH level of 8. A presumed blood sample is first collected with a swab.
A drop of phenolphthalein reagent is added to the sample, and after a few seconds, a drop of hydrogen peroxide is applied to the swab. If the swab turns pink rapidly, it is said to test presumptive positive for blood. Phenolphthalein is naturally colourless and works differently then litmus paper. Also, it turns in pink colour in an alkaline solution or base. Olfactory Indicators: Substances which change their smell when mixed with acid or base are known as olfactory indicators.
For example onion, vanilla, clove, etc. Olfactory indicators are used to ensure the participation of visually impaired students in laboratory. Onion: Paste or juice of onion loses its smell when added with base. It does not change its smell with acid. Synthetic Indicator: Indicators that are synthesized in laboratory are known as synthetic indicators.
For example; phenolphthalein, methyl orange, etc. Phenolphthalein is a colourless liquid. It remains colourless with acid but turns into pink with a base. Methyl orange is originally orange in colour. It turns into red with acid and turns into yellow with base. Using a litmus paper, phelophthalein, methyl orange, etc. So, to get the strength as well as acidic and basic nature of a given solution universal indicator is used.
Universal indicator shows different colour over the range of pH value from 1 to 14 for a given solution. Universal indicator is available both in the form of strips and solution. Universal indicator is the combination of many indicators, such as water, propanol, phelophthalein, sodium salt, sodium hydroxide, methyl red, bromothymol blue monosodium salt, and thymol blue monosodium salt.
The colour matching chart is supplied with universal indicator which shows the different colours for different values of pH. Acid Base and Salt Strength of Acid and Base Acids in which complete dissociation of hydrogen ion takes place are called strong acid. Indicator: Substances which show the acidic or basic behavior of other substance by change in colour are known as indicator.
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