Salmeterol

Salmeterol, belonging to the pharmacological class Long-acting Beta 2 Adrenergic Agonist, acts as a Bronchodilator therapeutic agent. It acts via Beta-2 adrenoreceptor stimulation causing relaxation of bronchial smooth muscle, Bronchodilation, and increased airflow.

Salmeterol is used to maintain and prevent Asthma conditions and also in maintaining COPD conditions (Chronic Obstructive Pulmonary Disease). Salmeterol also helps in reducing breathing difficulties in Exercise-Induced Bronchoconstriction.

It has a relatively slow onset of action, i.e.10 to 30 minutes.

Salmeterol has more than twelve hours of effect duration with Tmax of 0.240h & Cmax of 47.897pg/ml.

Metered Dose Inhalers:

1. Remove cap. Some caps must be squeezed at the sides to release it.

2. Check the dose counter of the device.

3. Hold the inhaler upright and shake well before use.

4. Breathe out gently away from the inhaler before inhaling.

5. Put the mouthpiece between teeth and close lips tightly

6. Breathe in slowly through the mouth and at the same time press down firmly on the canister slowly simultaneously

7. Take a slow and deep breath

8. Hold the breath for about 5 or 10 seconds or as long as comfortable

9. While holding your breath, remove the inhaler from the mouth

10. Breathe out gently away from the inhaler

11. Repeat all steps starting from step 3, if more than one dose is needed,

12. Replace the cap

Powdered Inhalations:

1. It is advised to read the manufacturer's instructions for preparing the inhaler for first use and then using your inhaler correctly.

2. The cap is removed.

3. Then breathe out slowly and put the end of the mouthpiece in your mouth. Close your lips around it and point the inhaler towards the back of your throat.

4. While breathing in through the mouth, press the dose release button and continue to breathe in slowly, as long as you can. Hold your breath for around 10 seconds and then breathe out.

5. For the second puff repeat steps 3 and 4 above

Salmeterol can be used in the treatment of:

• Asthma
• Chronic Obstructive Pulmonary Disease (COPD)
• Emphysema
• Chronic Bronchitis
• Exercises Induced Bronchospasm

Salmeterol can help to reduce swelling in the airways, which in turn leads to Bronchodilation. Salmeterol is used to maintain and prevent Asthma conditions and also in maintaining COPD conditions (Chronic Obstructive Pulmonary Disease). Salmeterol also helps in reducing breathing difficulties in Exercise-Induced Bronchoconstriction.

Salmeterol is approved for use in the following clinical indications:

• Asthma: Salmeterol Inhalation Aerosol is indicated for long-term, twice-daily (morning and evenings) administration in the maintenance treatment of asthma and in the prevention of bronchospasm in patients 12 years of age and older with reversible obstructive airway disease, including patients with symptoms of nocturnal asthma, who require regular treatment with inhaled, short-acting beta2-agonists. It should not be used in patients whose asthma can be managed by the occasional use of inhaled, short-acting beta2-agonists. Salmeterol Inhalation Aerosol may be used alone or in combination with inhaled or systemic corticosteroid therapy. Salmeterol Inhalation Aerosol is also indicated for the prevention of exercise-induced bronchospasm in patients 12 years of age and older.
• Chronic Obstructive Pulmonary Disease: Salmeterol Inhalation Aerosol is indicated for long-term, twice-daily (morning and evening) administration in the maintenance treatment of bronchospasm associated with COPD (including emphysema and chronic bronchitis).

Salmeterol Inhalation Aerosol should be administered by the orally inhaled route only. It is recommended to "test spray" Salmeterol Inhalation Aerosol into the air four times before using for the first time and in cases where the aerosol has not been used for a prolonged period of time (i.e., more than four weeks).

• Asthma: For maintenance of bronchodilation and prevention of symptoms of asthma, including the symptoms of nocturnal asthma, the usual dosage for patients 12 years of age and older is two inhalations (42 mcg) twice daily (morning and evening, approximately 12 hours apart). Adverse effects are more likely to occur with higher doses of Salmeterol, and more frequent administration or administration of a larger number of inhalations is not recommended. To gain a full therapeutic benefit, Salmeterol Inhalation Aerosol should be administered twice daily (morning and evening) in the treatment of reversible airway obstruction.

If a previously effective dosage regimen fails to provide the usual response, medical advice should be sought immediately as this is often a sign of destabilization of asthma. Under these circumstances, the therapeutic regimen should be re-evaluated, and additional therapeutic options, such as inhaled or systemic corticosteroids, should be considered. If symptoms arise in the period between doses, an inhaled, short-acting beta2-agonist should be taken for immediate relief.

• Chronic Obstructive Pulmonary Disease: For maintenance treatment of bronchospasm associated with COPD (including chronic bronchitis and emphysema), the usual dosage for adults is 2 inhalations (42 mcg) twice daily (morning and evening, approximately 12 hours apart).
• Prevention of Exercise-Induced Bronchospasm: Two inhalations at least 30 to 60 minutes before exercise have been shown to protect against EIB in many patients for up to 12 hours. Additional doses of Salmeterol Inhalation Aerosol should not be used for 12 hours after the administration of this drug. Patients who are receiving Salmeterol Inhalation Aerosol twice daily (morning and evening) should not use additional Salmeterol Inhalation Aerosol for the prevention of EIB. If this dose is not effective, other appropriate therapy for EIB should be considered.
• Geriatric Use: In studies where geriatric patients (65 years of age or older) have been treated with Salmeterol Inhalation Aerosol, the efficacy, and safety of 42 mcg were given twice daily (morning and evening) did not differ from that in younger patients. Consequently, no dosage adjustment is recommended.

The dosage and duration of treatment should be as per the clinical judgment of the treating physician.

The Salmeterol is available in dosage strengths of 21mcg,50mcg, and 100mcg.

 Salmeterol is available in the form of Metered Dose Inhalers.

Salmeterol should be used in the treatment of Bronchial Asthma & COPD along with appropriate dietary restrictions.

The dietary restriction should be individualized as per patient requirements.

Salmeterol may be contraindicated with a history of hypersensitivity to Salmeterol or any other component of the drug product containing a single or combination of Salmeterol.

The treating physician must closely monitor the patient and keep pharmacovigilance as follows:

Data from a large Placebo-controlled safety study that was stopped early suggest that salmeterol may be associated with rare.

• Serious asthma episodes or asthma-related deaths. Data from this study, called the Salmeterol Multi-center Asthma Research Trial (SMART), further suggest that the risk might be greater in African American patients. These results led to stopping the study prematurely.
• Asthma: Salmeterol Multi-center Asthma Research Trial. The data from the (SMART study are inadequate to determine whether concurrent use of inhaled corticosteroids protects from this risk. Given the similar basic mechanisms of action of beta2-agonists, the findings seen in the SMART study may be consistent with a class effect).
• Findings similar to the SMART study findings were reported in a prior 16-week clinical study performed in the United Kingdom, the Salmeterol Nationwide Surveillance (SNS) study. In the SNS study, the incidence of asthma-related death was numerical, though not statistically, greater in patients more significant and treated with Salmeterol (42 mcg twice daily) versus albuterol (180 mcg 4 times daily) added to usual asthma therapy.

Salmeterol inhalation aerosol should not be initiated in:

• Patients with significantly worsening or acutely deteriorating asthma, which may be a life-threatening condition. Serious acute respiratory events, including fatalities, have been reported, both in the United States and worldwide when Salmeterol Inhalation Aerosol has been initiated in this situation.
• Although it is not possible from these reports to determine whether Salmeterol Inhalation Aerosol contributed to these adverse events or simply failed to relieve deteriorating asthma, the use of Salmeterol Inhalation Aerosol in this setting is inappropriate.

Salmeterol Inhalation Aerosol should not be used to treat:

• Acute symptoms: It is crucial to inform patients of this and prescribe an inhaled, short-acting beta2-agonist for this purpose, as well as warn them that increasing inhaled beta2-agonist use is a signal of deteriorating asthma.
• Salmeterol inhalation aerosol is not a substitute for inhaled or oral corticosteroid. Corticosteroids should not be stopped or reduced when Salmeterol Inhalation Aerosol is initiated.

Salmeterol has shown Plasma levels after inhaled therapeutic doses to be very low. In rats, salmeterol xinafoate is excreted in milk. However, since there is no experience with the use of Salmeterol Inhalation Aerosol by nursing mothers, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother. Caution should be exercised when salmeterol xinafoate is administered to a nursing woman.

Salmeterol –has some Teratogenic Effects:

Pregnancy Category C: No teratogenic effects occurred in the rat at oral doses up to 2 mg/kg (approximately 160 times the maximum recommended human daily inhalation dose in adults on an mg/m2 basis). In pregnant Dutch rabbits administered oral doses of 1 mg/kg and above (approximately 20 times the maximum recommended human daily inhalation dose in adults based on the comparison of the AUCs), salmeterol xinafoate exhibited fetal toxic effects characteristically resulting from beta-adrenoceptor stimulation; these included precocious eyelid openings, cleft palate, sternebrae fusion, limb and paw flexures, and delayed ossification of the frontal cranial bones. No significant effects occurred at an oral dose of 0.6 mg/kg (approximately ten times the maximum recommended human daily inhalation dose in adults based on a comparison of the AUCs). New Zealand White rabbits were less sensitive since only delayed ossification of the frontal cranial bones was seen at oral doses of 10 mg/kg (approximately 1,600 times the maximum recommended human daily inhalation dose on an mg/m2 basis). Extensive use of 17 other beta-agonists has provided no evidence that these class effects in animals are relevant to use in humans. There are no adequate and well-controlled studies on Salmeterol Inhalation Aerosol in pregnant women. Salmeterol Inhalation Aerosol should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

It's advised that taking grapefruit or grapefruit juice should be avoided while using Salmeterol.

The adverse reactions related to Salmeterol can be categorized as:

Common:(1% to 10%)

• Arthralgia, articular rheumatism, muscle cramps and spasm, bone and skeletal pain, muscle pain, muscle stiffness, muscle tightness, muscle rigidity, musculoskeletal inflammation
• Dizziness, migraines, tremor
• Pallor, hypertension, palpitations
• Skin rashes, urticaria, photodermatitis
• Gastrointestinal signs and symptoms, nausea, vomiting, candidiasis mouth/throat, dental discomfort and pain, dyspeptic symptoms, gastrointestinal infections, hyposalivation
• Hyperglycemia
• Conjunctivitis, keratitis
• Nasal/sinus congestion, rhinitis, asthma, tracheitis/bronchitis, pharyngitis, sinusitis, upper respiratory tract infection, cough, throat irritation, lower respiratory signs, and symptoms

Less Common :

• Anxiety
• Belching
• Bone pain
• Burning, dry, or itching eyes
• Difficulty with moving
• Discharge or excessive tearing
• Eye redness, irritation, or pain
• Headache, severe and throbbing
• Heartburn
• Indigestion
• Mouth or tooth pain
• Muscle cramps, spasms, stiffness, or tightness
• Redness of the skin
• Redness, pain, or swelling of the eye, eyelid, or inner lining of the eyelid
• Stomach discomfort or upset

Rare:

• Choking or feeling of choking
• Difficulty swallowing
• Extra heartbeat
• Fainting
• Fast, pounding, or irregular heartbeat or pulse
• Hives or welts
• Mouth irritation
• Puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
• Slow heartbeat

The clinically relevant drug interactions of Salmeterol are briefly summarized here:

• Short-Acting Beta2-Agonists: In the two 3-month, repetitive-dose 436 clinical asthma trials (N = 184), the mean daily need for additional beta2-agonist use was 1 to 1½ 437 inhalations/day, but some patients used more. Eight percent (8%) of patients used at least 8 inhalations/day on at least one occasion. Six percent (6%) used 9 to 12 inhalations at least once. There were 15 patients (8%) who averaged over 4 inhalations/day. Four (4) of these used an average of 8 to 11 inhalations/day. In these 15 patients, there was no observed increase in the frequency of cardiovascular adverse events. The safety of concomitant use of more than 8 inhalations/day of short-acting beta2-agonists with Salmeterol Inhalation Aerosol has not been established. In 15 patients who experienced worsening asthma while receiving Salmeterol Inhalation Aerosol, nebulized albuterol (1 dose in most) led to improvement in FEV1 and no increase in the occurrence of cardiovascular adverse events.
• Monoamine Oxidase Inhibitors and Tricyclic Antidepressants: Salmeterol should be administered with extreme caution to patients being treated with monoamine oxidase inhibitors or tricyclic antidepressants, or within 2 weeks of discontinuation of such agents, because the action of Salmeterol on the vascular system may be potentiated by these agents.
• Corticosteroids and Cromoglycate: In clinical trials, inhaled corticosteroids and/or inhaled cromolyn sodium did not alter the safety profile of Salmeterol Inhalation Aerosol when administered concurrently.
• Methylxanthines: The concurrent use of intravenously or orally administered methylxanthines (e.g., aminophylline, theophylline) by patients receiving Salmeterol Inhalation Aerosol has not been completely evaluated in 1 clinical asthma trial, 87 patients received.

Salmeterol Inhalation Aerosol 42 mcg twice daily concurrently with a theophylline product had adverse event rates similar to those in 71 patients receiving Salmeterol Inhalation Aerosol without theophylline. Resting heart rates were slightly higher in the patients on theophylline but were little affected by Salmeterol Inhalation Aerosol therapy. Beta-adrenergic receptor blocking agents not only block the pulmonary effect of beta-agonists, such as Salmeterol Inhalation Aerosol but may also produce severe bronchospasm in patients with asthma. Therefore, patients with asthma should not normally be treated with beta-blockers. However, under certain circumstances, e.g., as prophylaxis after myocardial infarction, there may be no acceptable alternatives to the use of beta-adrenergic blocking agents in patients with asthma. In this setting, cardioselective beta-blockers could be considered, although they should be administered with caution. The ECG changes and/or hypokalaemia that may result from the administration of non-potassium-sparing diuretics (such as loop or thiazide diuretics) can be acutely worsened by beta-agonists, especially when the recommended dose of the beta-agonist is exceeded. Although the clinical significance of these effects is not known, caution is advised in the coadministration of beta-agonists with non-potassium-sparing diuretics.

The common side of Salmeterol includes the following:

• Worsening asthma symptoms or other breathing problems after using Salmeterol
• Severe headache, blurred vision, pounding in your neck or ears
• Chest pain, fast or irregular heartbeats
• Tremors, nervousness
• High blood sugar--increased thirst, increased urination, dry mouth, fruity breath odour; or
• Low potassium level--leg cramps, constipation, irregular heartbeats, fluttering in your chest, increased thirst or urination, numbness or tingling, muscle weakness, or limp feeling.
• Headache
• Flu symptoms
• Joint or muscle pain
• Throat irritation, cough; or
• Stuffy or runny nose.

The use of Salmeterol should be prudent in the following group of special populations:

• Pregnancy Teratogenic Effects Pregnancy Category C

No teratogenic effects occurred in rats at oral doses up to 2 mg/kg (approximately 160 times the maximum recommended daily inhalation dose in adults on an mg/m2 basis). In pregnant Dutch rabbits administered oral doses of 1 mg/kg and above (approximately 50 times the maximum recommended daily inhalation dose in adults based on a comparison of the AUCs), Salmeterol exhibited fetal toxic effects characteristically resulting from beta-adrenoceptor stimulation. These included precocious eyelid openings, cleft palate, sternebral fusion, limb and paw flexures, and delayed ossification of the frontal cranial bones. No significant effects occurred at an oral dose of 0.6 mg/kg (approximately 20 times the maximum recommended daily inhalation dose in adults based on a comparison of the AUCs). New Zealand White rabbits were less sensitive since only delayed ossification of the frontal bones was seen at an oral dose of 10 mg/kg (approximately 1,600 times the maximum recommended daily inhalation dose in adults on an mg/m2 basis). Extensive use of other beta-agonists has provided no evidence that these class effects in animals are relevant to their use in humans. There are no adequate and well-controlled studies on Salmeterol in pregnant women. Salmeterol should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Salmeterol xinafoate crossed the placenta following oral administration of 10 mg/kg to mice and rats (approximately 410 and 810 times, respectively, the maximum recommended daily inhalation dose in adults on an mg/m2 basis).

• Use in Labor and Delivery

There are no well-controlled human studies that have investigated the effects of Salmeterol on preterm labor or labor at term. Because of the potential for beta-agonist interference with uterine contractility, the use of Salmeterol during labor should be restricted to those patients in whom the benefits clearly outweigh the risks.

• Nursing Mothers

Plasma levels of Salmeterol after inhaled therapeutic doses are very low. In rats, salmeterol xinafoate is excreted in the milk. However, since there are no data from controlled trials on the use of Salmeterol by nursing mothers, a decision should be made whether to discontinue nursing or discontinue Salmeterol, taking into account the importance of Salmeterol to the mother. Caution should be exercised when Salmeterol is administered to a nursing woman.

• Pediatric Use

The safety and efficacy of Salmeterol have been evaluated in over 2,500 patients aged 4 to 11 years with asthma, 346 of whom were administered Salmeterol for 1 year. Based on available data, no adjustment of dosage of Salmeterol in paediatric patients is warranted for either asthma or EIB. In 2 randomized, double-blind, controlled clinical trials of 12 weeks' duration, Salmeterol 50 mcg was administered to 211 paediatric patients with asthma who did and who did not receive concurrent inhaled corticosteroids. The efficacy of Salmeterol was demonstrated over the 12-week treatment period with respect to PEF and FEV1. Salmeterol was effective in demographic subgroups (gender and age) of the population. Salmeterol was effective when co-administered with other inhaled asthma medications, such as short-acting bronchodilators and inhaled corticosteroids. Salmeterol was well tolerated in the paediatric population, and there were no safety issues identified specific to the administration of Salmeterol to paediatric patients. In 2 randomized studies in children 4 to 11 years old with asthma and EIB, a single 50-mcg dose of Salmeterol prevented EIB when dosed 30 minutes prior to exercise, with protection lasting up to 11.5 hours in repeat testing following this single dose in many patients.

• Geriatric Use

Of the total number of adolescent and adult patients with asthma who received Salmeterol in chronic dosing clinical trials, 209 were 65 years of age and older. Of the total number of patients with COPD who received Salmeterol in chronic dosing clinical trials, 167 were 65 years of age or older, and 45 were 75 years of age or older. No apparent differences in the safety of Salmeterol were observed when geriatric patients were compared with younger patients in clinical trials. As with other beta2-agonists, however, special caution should be observed when using Salmeterol in geriatric patients who have concomitant cardiovascular disease that could be adversely affected by this class of drug. Data from the trials in patients with COPD suggested a greater effect on FEV1 of Salmeterol.

The physician should be vigilant about the knowledge pertaining to the identification and treatment of overdosage of Salmeterol. The expected signs and symptoms with overdosage are those of excessive beta-adrenergic stimulation and/or occurrence or exaggeration of any of the symptoms listed under Adverse reactions, e.g. seizures, angina, hypertension or hypotension, tachycardia with rates up to 200 beats/min, arrhythmias, nervousness, headache, tremor, muscle cramps, dry mouth, palpitation, nausea, dizziness, fatigue, malaise, and insomnia. Overdosage with Salmeterol Inhalation Aerosol may be expected to result in exaggeration of the pharmacologic adverse effects associated with beta-adrenoceptor agonists, including tachycardia and/or arrhythmia, tremor, headache, and muscle cramps. Overdosage with Salmeterol Inhalation Aerosol can lead to a clinically significant prolongation of the QTc interval, which can produce ventricular arrhythmias. Other signs of overdose may include hypokalaemia and hyperglycaemia. As with all sympathomimetic aerosol medications, cardiac arrest and even death may be associated with abuse of Salmeterol Inhalation Aerosol. Treatment consists of discontinuation of Salmeterol Inhalation Aerosol together with appropriate symptomatic therapy. The judicious use of a cardioselective beta-receptor blocker may be considered, bearing in mind that such medication can produce bronchospasm.

There is insufficient evidence to determine if dialysis is beneficial for the overdosage of Salmeterol Inhalation Aerosol. Cardiac monitoring is recommended in cases of overdosage. No deaths were seen in rats at inhalation doses of 2.9 mg/kg (approximately 240 times the maximum recommended human daily inhalation dose on an mg/m2 basis) and in dogs at 0.7 mg/kg (approximately 190 times the maximum recommended human daily inhalation dose on an mg/m2 basis). By the oral route, no deaths occurred in mice at 150 mg/kg (approximately 6,100 times the maximum recommended human daily inhalation dose on an mg/m2 basis) and in rats at 1,000 mg/kg (approximately 81,000 times the maximum recommended human daily inhalation dose on an mg/m2 basis).

Pharmacodynamics:

Salmeterol is a long-acting beta-2 adrenergic receptor agonist that binds to both the active and exo- sites of the beta-2 adrenergic receptor. Salmeterol has a longer duration of action than other beta-2 agonists like salbutamol. Patients should be counseled regarding the risks of long-acting beta-agonist (LABA) monotherapy, hypokalemia, and hypoglycemia, and not to take this drug with other LABAs.

Pharmacokinetics:

Salmeterol xinafoate, an ionic salt, dissociates in solution so that the salmeterol and 1-hydroxy-2-naphthoic acid (xinafoate) moieties are absorbed, distributed, metabolized, and eliminated independently. Salmeterol acts locally in the lung; therefore, plasma levels do not predict therapeutic effects.

Absorption:

Because of the small therapeutic dose, systemic levels of salmeterol are low or undetectable after inhalation of recommended doses (50 mcg of salmeterol inhalation powder twice daily). Following chronic administration of an inhaled dose of 50 mcg of salmeterol inhalation powder twice daily, salmeterol was detected in plasma within 5 to 45 minutes in 7 patients with asthma; plasma concentrations were very low, with mean peak concentrations of 167 pg/mL at 20 minutes and no accumulation with repeated doses.

Distribution:

The percentage of Salmeterol bound to human plasma proteins averages 96% in vitro over the concentration range of 8 to 7,722 ng of salmeterol base per milliliter, much higher concentrations than those achieved following therapeutic doses of Salmeterol.

Metabolism:

Salmeterol base is extensively metabolized by hydroxylation, with subsequent elimination predominantly in the feces. No significant amount of unchanged salmeterol base has been detected in either urine or feces. An in vitro study using human liver microsomes showed that Salmeterol is extensively metabolized to a-hydroxysalmeterol (aliphatic oxidation) by cytochrome P450 3A4 (CYP3A4). Ketoconazole, a potent inhibitor of CYP3A4, essentially completely inhibited the formation of a-hydroxysalmeterol in vitro.

Elimination:

In 2 healthy subjects who received 1 mg of radiolabeled salmeterol (as salmeterol xinafoate) orally, approximately 25% and 60% of the radiolabeled Salmeterol were eliminated in urine and feces, respectively, over a period of 7 days. The terminal elimination half-life was about 5.5 hours (1 volunteer only). The xinafoate moiety has no apparent pharmacologic activity. The xinafoate moiety is highly protein-bound (>99%) and has a long elimination half-life of 11 days.

1. https://www.accessdata.fda.gov/drugsatfda_docs/label/2004/20236s030,20692s026lbl.pdf

2.https://www.wellrx.com/fluticasonesalmeterol/lifestyleinteractions/#:~:text=Notes for Consumers: Do not drink grapefruit juice or eat,new or unusual side effects.

3. https://www.accessdata.fda.gov/drugsatfda_docs/label/2007/020692s028lbl.pdf

4. https://go.drugbank.com/drugs/DB00938

5. drugs.com/mtm/salmeterol/-inhalation.html#side-effects