Cofrest

Uses

1. Expectorant in cough syrups.
2. The ammonium ion (NH4+) in the body plays an important role in the maintenance of acid-base balance. The kidney uses ammonium (NH4+) in place of sodium (Na+) to combine with fixed anions in maintaining acid-base balance, especially as a homeostatic compensatory mechanism in metabolic acidosis. The therapeutic effects of Ammonium Chloride depend upon the ability of the kidney to utilize ammonia in the excretion of an excess of fixed anions and the conversion of ammonia to urea by the liver, thereby liberating hydrogen (H+) and chloride (Cl–) ions into the extracellular fluid. Ammonium Chloride Injection, USP, after dilution in isotonic sodium chloride injection, may be indicated in the treatment of patients with: (1) hypochloremic states and (2) metabolic alkalosis.

Diphenhydramine is used for the treatment of followings:

• Seasonal, perennial, vasomotor rhinitis
• Urticaria, angioneurotic oedema, anaphylaxis
• Pruiritic conditions
• Premedication for emesis and motion sickness
• Miscellaneous like meniere's disease and parkinsonism

This is used for the symptomatic treatment of reversible bronchoconstriction associated with bronchial asthma, chronic obstructive pulmonary emphysema, chronic bronchitis and related bronchospastic disorders.

Cofrest is also used to associated treatment for these conditions: Allergic Reaction, Allergic cough, Common Cold, Cough, Cough caused by Common Cold, Diabetes, High Blood Pressure (Hypertension), Metabolic Alkalosis, Nasal Congestion, Nasal Congestion Due to Allergic Rhinitis, Productive cough, Rhinorrhoea, Sneezing, Bronchial congestion, Dry cough, Excess mucus or phlegm, Hypochloremic state, Airway secretion clearance therapy, Bronchodilation, Parenteral rehydration therapy, Weight Loss, PotassiumAllergic Rhinitis (AR), Allergic cough, Allergies, Anaphylaxis, Angioedema, Common Cold, Common Cold/Flu, Conjunctival irritation, Cough, Cough Variant Asthma, Cough caused by Common Cold, Eye allergy, Fever, Insect Bites, Insect Stings, Insomnia, Irritative cough, Itching of the nose, Itching of the throat, Motion Sickness, Nasal Congestion, Oral Mucositis, Pain, Parkinsonian Syndromes, Pollen Allergy, Productive cough, Pruritus, Rash, Rhinorrhoea, Sinus Congestion, Sinus headache, Skin Irritation, Sneezing, Sunburn, Symptoms of Acute Bronchitis Accompanied by Coughing, Upper respiratory tract hypersensitivity reaction, site unspecified, Urticaria, Dermatographism, Dry cough, Watery itchy eyes, Airway secretion clearance therapy, ExpectorantAsthma, Bronchitis, Bronchoconstriction, Bronchospasm, Chronic Obstructive Pulmonary Disease (COPD), Chronic bronchial inflammation, Airway secretion clearance therapy, Bronchodilation

How Cofrest works

Ammonium chloride increases acidity by increasing the amount of hydrogen ion concentrations.

Ammonium chloride can be used as an expectorant due to its irritative action on the bronchial mucosa. This effect causes the production of respiratory tract fluid which in order facilitates the effective cough.

Diphenhydramine predominantly works via the antagonism of H1 (Histamine 1) receptors . Such H1 receptors are located on respiratory smooth muscles, vascular endothelial cells, the gastrointestinal tract (GIT), cardiac tissue, immune cells, the uterus, and the central nervous system (CNS) neurons . When the H1 receptor is stimulated in these tissues it produces a variety of actions including increased vascular permeability, promotion of vasodilation causing flushing, decreased atrioventricular (AV) node conduction time, stimulation of sensory nerves of airways producing coughing, smooth muscle contraction of bronchi and the GIT, and eosinophilic chemotaxis that promotes the allergic immune response .

Ultimately, diphenhydramine functions as an inverse agonist at H1 receptors, and subsequently reverses effects of histamine on capillaries, reducing allergic reaction symptoms . Moreover, since diphenhydramine is a first-generation antihistamine, it readily crosses the blood-brain barrier and inversely agonizes the H1 CNS receptors, resulting in drowsiness, and suppressing the medullary cough center .

Furthermore, H1 receptors are similar to muscarinic receptors . Consequently, diphenhydramine also acts as an antimuscarinic . It does so by behaving as a competitive antagonist of muscarinic acetylcholine receptors, resulting in its use as an antiparkinson medication .

Lastly, diphenhydramine has also demonstrated activity as an intracellular sodium channel blocker, resulting in possible local anesthetic properties .

Theophylline relaxes the smooth muscle of the bronchial airways and pulmonary blood vessels and reduces airway responsiveness to histamine, methacholine, adenosine, and allergen. Theophylline competitively inhibits type III and type IV phosphodiesterase (PDE), the enzyme responsible for breaking down cyclic AMP in smooth muscle cells, possibly resulting in bronchodilation. Theophylline also binds to the adenosine A2B receptor and blocks adenosine mediated bronchoconstriction. In inflammatory states, theophylline activates histone deacetylase to prevent transcription of inflammatory genes that require the acetylation of histones for transcription to begin.

Dosage

Cofrest dosage

Adult-

• Most allergic conditions: 25-50 mg three times a day with a further 50 mg at night.

Children-

• 1 to 5 years of age: 5 mg i.e., 2.5 ml of elixir 4 times a day
• More than 6 years of age: 10 mg i.e. 5 ml of elixir 4 times a day

Dosages are adjusted to maintain serum theophylline concentrations that provide optimal relief of symptoms with minimal side effects. Most of the controlled release preparations may be administered every 12 hours in adults while administration every 8 hours may be necessary in some children with markedly rapid hepatic metabolism of theophylline. The recommended dosages for achieving serum theophylline concentrations within the accepted therapeutic range is as follow:

• 1-6 months: 10mg/Kg/day
• 6 months-1 year: 15mg/Kg/day
• 1-9 years: 24mg/Kg/day
• 10-16 years: 18mg/Kg/day
• Adults: 10-15mg/Kg/day

Side Effects

Side effect includes sedation, dizziness, tinnitus, fatigue, ataxia, blurred vision, diplopia, euphoria, and epigastric discomfort.

The following side effects have been observed:

Gastrointestinal: Nausea, vomiting, epigastric pain and diarrhoea.

Central nervous system: Headache, irritability, restlessness, insomnia, muscles twitching.

Cardiovascular: Palpitation, tachycardia, hypotension. circulatory failure.

Respiratory: Tachypnoea.Renal: Potentiation of diuresis.

Others: Alopecia, hyperglycemia, rash etc.

Toxicity

LD50 "Rat" after oral administration is: 1650 mg/kg. Overdosage of Ammonium Chloride has resulted in a serious degree of metabolic acidosis, disorientation, confusion and coma. If metabolic acidosis occur following overdosage, the administration of an alkalinizing solution such as sodium bicarbonate or sodium lactate will serve to correct the acidosis.

Patients administering Ammonium chloride should be watched to the signs of ammonia toxicity including (pallor, sweating, irregular breathing, bradycardia, cardiac arrhythmias, local and general twitching, tonic convulsions and coma). It should be used with caution in patients with high total CO2 and buffer base secondary to primary respiratory acidosis. Intravenous administration should be slow to avoid local irritation and toxic effects.

Overdose is expected to result in effects similar to the adverse effects that are ordinarily associated with the use of diphenhydramine, including drowsiness, hyperpyrexia, and anticholinergic effects, among others . Additional symptoms during overdose may include mydriasis, fever, flushing, agitation, tremor, dystonic reactions, hallucinations and ECG changes . Large overdose may cause rhabdomyolysis, convulsions, delirium, toxic psychosis, arrhythmias, coma and cardiovascular collapse . Moreover, with higher doses, and particularly in children, symptoms of CNS excitation including hallucinations and convulsions may appear; with massive doses, coma or cardiovascular collapse may follow .

Although diphenhydramine has been in widespread use for many years without ill consequence, it is known to cross the placenta and has been detected in breast milk . This medication should therefore only be used when the potential benefit of treatment to the mother exceeds any possible hazards to the developing fetus or suckling infant .

Pharmacokinetic studies indicate no major differences in the distribution or elimination of diphenhydramine compared to younger adults . Nevertheless, diphenhydramine should be used with caution in the elderly, who are more likely to experience adverse effects . Avoid use in elderly patients with confusion .

The results of a review on the use of diphenhydramine in renal failure suggest that in moderate to severe renal failure, the dose interval should be extended by a period dependent on Glomerular filtration rate (GFR) .

After intravenous administration of 0.8 mg/kg diphenhydramine, a prolonged half-life was noted in patients with chronic liver disease which correlated with the severity of the disease . However, the mean plasma clearance and apparent volume of distribution were not significantly affected .

LD₅₀=500 mg/kg (orally in rats). Considerable overdosage can lead to myocardial infarction (heart attack), serious ventricular dysrhythmias, coma and death.

Symptoms of overdose include seizures, arrhythmias, and GI effects.

Precaution

Caution should be exercised with patients in whom drowsiness is undesirable e.g., drivers, machine operators. Concomitant consumption of alcohol or central nervous system (CNS) depressants will potentiate drowsiness.

Careful consideration is needed for various interacting drugs and physiologic conditions that can alter Theophylline clearance. Dosage adjustment is required prior to initiation of Theophylline therapy, prior to increases in Theophylline dose, and during follow up. The dose of Theophylline selected for initiation of therapy should be low and, if tolerated, increased slowly over a period of time.

Interaction

Diphenhydramine administration significantly reduces the absorption of the antituberculous agent para-aminosalicyclic acid (PAS) from the gastrointestinal tract. CNS depressants may potentiate the sedative action of Diphenhydramine. Anticholinergic drugs may potentiate Diphenhydramine’s anticholinergic side effects.

Allopurinol, cimetidine, norfloxacin, ciprofloxacin, erythromycin, oral contraceptives and propranolol increase serum theophylline levels. Phenytoin, methotrexate and rifampicin lead to decreased serum theophylline levels

Volume of Distribution

Data not found.

Diphenhydramine is widely distributed throughout the body, including the CNS . Following a 50 mg oral dose of diphenhydramine, the volume of distribution is in the range of 3.3 - 6.8 l/kg .

• 0.3 to 0.7 L/kg

Elimination Route

Completely absorbed within 3–6 h. In healthy persons, absorption of ammonium chloride given by mouth was practically complete. Only 1 to 3% of the dose was recovered in the feces.

Diphenhydramine is quickly absorbed after oral administration with maximum activity occurring in approximately one hour . The oral bioavailability of diphenhydramine has been documented in the range of 40% to 60%, and peak plasma concentration occurs about 2 to 3 hours after administration .

Theophylline is rapidly and completely absorbed after oral administration in solution or immediate-release solid oral dosage form.

Half Life

Unknown

The elimination half-life ranges from 2.4-9.3 hours in healthy adults . The terminal elimination half-life is prolonged in liver cirrhosis .

8 hours

Clearance

Data not found.

Values for plasma clearance of a 50 mg oral dose of diphenhydramine has been documented as lying in the range of 600-1300 ml/min .

• 0.29 mL/kg/min [Premature neonates, postnatal age 3-15 days]
• 0.64 mL/kg/min [Premature neonates, postnatal age 25-57 days]
• 1.7 mL/kg/min [Children 1-4 years]
• 1.6 mL/kg/min [Children 4-12 years]
• 0.9 mL/kg/min [Children 13-15 years]
• 1.4 mL/kg/min [Children 16-17 years]
• 0.65 mL/kg/min [Adults (16-60 years), otherwise healthy non-smoking asthmatics]
• 0.41 mL/kg/min [Elderly (>60 years), non-smokers with normal cardiac, liver, and renal function]
• 0.33 mL/kg/min [Acute pulmonary edema]
• 0.54 mL/kg/min [COPD >60 years, stable, non-smoker >1 year]
• 0.48 mL/kg/min [COPD with cor pulmonale]
• 1.25 mL/kg/min [Cystic fibrosis (14-28 years)]
• 0.31 mL/kg/min [Liver disease cirrhosis]
• 0.35 mL/kg/min [acute hepatitis]
• 0.65 mL/kg/min [cholestasis]
• 0.47 mL/kg/min [Sepsis with multi-organ failure]
• 0.38 mL/kg/min [hypothyroid]
• 0.8 mL/kg/min [hyperthyroid]

Elimination Route

Excretion: Urine

The metabolites of diphenhydramine are conjugated with glycine and glutamine and excreted in urine . Only about 1% of a single dose is excreted unchanged in urine . The medication is ultimately eliminated by the kidneys slowly, mainly as inactive metabolites .

Theophylline does not undergo any appreciable pre-systemic elimination, distributes freely into fat-free tissues and is extensively metabolized in the liver. Renal excretion of unchanged theophylline in neonates amounts to about 50% of the dose, compared to about 10% in children older than three months and in adults.

Pregnancy & Breastfeeding use

Category B: There are no adequate and well controlled studies in pregnant women using diphenhydramine hydrochloride. Therefore, diphenhydramine hydrochloride should be used in pregnancy only if clearly needed. Diphenhydramine hydrochloride has been reported to be excreted in breast milk and thus, use of diphenhydramine hydrochloride in lactating mother is not recommended.

Pregnancy: It is not known whether Theophylline can cause foetal harm when administered to pregnant woman.Xanthines should be given to a pregnant woman only if clearly needed.

Nursing mother: Theophylline is excreted into breast milk and may cause irritability or other signs of mild toxicity in nursing human infants. Serious adverse effects in the infant are unlikely unless the mother has toxic serum Theophylline concentrations.

Contraindication

Known hypersensitivity to Diphenhydramine Hydrochloride, Ammonium chloride is contra-indicated in presence of impaired hepatic or renal function.

Hypersensitivity to xanthine derivatives. It is also contraindicated in patients with active peptic ulcer disease and in individuals with underlying seizure disorders (unless receiving appropriate anti-convulsing medication).

Theophylline should not be administered concurrently with other xanthine. Use with caution in patients with hypoxemia, hypertension, or those with history of peptic ulcer. Do not attempt to maintain any dose that is not tolerated.

Acute Overdose

Symptoms: Impaired consciousness; psychosis, seizures, antimuscarinic symptoms (e.g. mydriasis, tachycardia, tachyarrhythmias), resp failure, rhabdomyolysis; acute delirium with visual and auditory hallucination (topical).

Management: Supportive and symptomatic treatment. Convulsions and marked CNS stimulation may be treated with IV diazepam.

Symptoms may include nausea, vomiting, gastrointestinal irritation, cramps, convulsions, tachycardia & hypotension. The stomach contents should be emptied & supportive measures employed to maintain circulation, respiration & fluid & electrolyte balance. Electrocardiographic monitoring should be carried out & in severe poisoning charcoal haemoperfusion should be used.

Storage Condition

Store between 15-30° C. Protect from moisture.

Store in a cool and dry place, protect from light and moisture. Keep out of the reach of children

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