Angiotensin II Receptor Antagonists- Candesartan, Eposartan, Irbestan, Losartan metabolite, Olmesartan, Telmistran, Valsartan 

Interacting drugs- summary

+ Losartan-

Cimetidine-                                                                                                                     coadministration led to an increase of about 18% in AUC of losartan but did not effect the pharmacikinetics of its active metabolite 

Phenobarbital-                                                                                                              coadministration led to a reduction of about 20% in the AUC of losartan and that of its active metabolite

Adverse Reactions-
 

LOSARTAN

CNS  -  Dizziness 4% ,Insomnia 1%,  Headache >1%,Fatigue < 1%, 

GI  -       Diarrhea 2%,  Dyspepsia/heartburn 1%  Nausea/vomiting >1%

               Abdominal pain >1%     

MUSCULOSKELETAL -  Arthalgia >1%, Pain  1% to 8% Muscle cramp 1%  Myalgia 1%

RESPIRATORY  -           Upper Res tract infn 8%,  Cough 3% 

                                          Nasal congestion 2%  Sinus disorder < 2%
                                           Sinusitis 1% Pharyngitis >1% Rhinitis > 1% 

                                           Influnz like symptoms >1% bronchitis >1%

MISCELLANEOUS -   Edema >1%  Chest pain  >1% Rash <1%   Tacycardia <1% 

                                       Urinary tract infn <1%
                            

Hypersensitivity to the product

Special precautions:

Lab tests- minor increases in blood urea nitrogen (BUN) or serum creatinine. Occassional elevations in liver enzymes.

Drug/food interactons- a meal slows absorption of losartan and decreases its Cmax but only minor effects on losartan AUC or on the metabolite

Warnings-

Hypotension/volume depleted patients- coorect these conditions prior to administration , or use a lower starting dose.

Monotherapy- in considering the use of losartan, note that in controlled trials losartan had an effect on blood pressure that was notably less in African-American patients than in non-Aftrican American

Gender- no dosage adjustment is necessary.

Renal function impairement- there has been no known use in losartan in patients with unilateral or bilateral renal artery stenosis, but anticipate a similar efect.

Hepatic functin impairment- a lower starting dose is recommended for patients with a history of hepatic impairment.

Elderly- plasma concentrations of losartan and its active metabolite are similar in elderly and in young hypertensives.

Pregnancy- when pregnancy is detected discontinue losartan as soon as possible.

Lactation- because of the potential for adverse effects on the nursing infant, decide whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.

Children- safety and efficacy in children have not been established.

Hypertension

Dosage:

Usual starting dose is 50mg once daily. Losartan may be administered with other antihypertensive agents

Overdosage- Symptoms

Limited data are available in regard to overdosage in humans. The most likely manifestations of overdosage would be hypotension and tachycardia, bradycardia could occur from parasympathetic (vagal ) stimulation If sympatomatic hypotension could occur,institute supportive treatment.

Treatment

1.If sympatomatic hypotension could occur,institute supportive treatment

2. Neither Losartan nor its metabolite can be removed hemodialysis.

 Missed dose-

 1. If you miss a dose of this medicine, take it as soon as possible.

2. However, if it is almost time for next dose, skip the missed dose and go back to your regular dosing schedule.

3. Do not double doses.

1. Tell female patients of childbearing age about the consequences of second and third trimester exposure to drugs that act on renin-angiotensin system, and tell them that these consequences do not appear to have resulted from intrauterine drug exposure that has has been limited to the first trimester.

2. Ask these patients to report pregnancies to their physicians as soon as possible.

3. Allergy- If you had any unusual reaction to losartan or food substances , preservatives , dyestuffs , you must inform your doctor,

4. Diet - If you are on a special diet - low  sodium diet, tell your  certain that your doctor diet.

5. Pregancy- Use of losartan in pregnancy especially during the second and third trimester ( after the first three months) can cause low blood pressure ,severe kidney failure or even death in the newborn.

6. Breast feeding- Not know whether losartan passes into breast milk. However, losartanpasses into breast in pregnant rats.

7. Elderly - Medicine tested in limited number of patients and has not shown to cause different side effects than in younger adults

8. Other medicines- Tell your doctor if you are taking other prescription or non-prescrition OTC medicines

9. Other medical problems- Your doctor should know if you are having other medical problems. - Kidney disease or Liver disease - effects may be increased because of slower removaloflosartan from the body.

10. Dosing- Follow doctors instructions

11. Missed dose- If you miss a dose of this medicine take it as soon as possible. However if it is almost time for your next dose go back to your regular dosing schedule. Do not double doses.

12. Storage- Keep the medicines out of reach of children Store the medicines away heat and direct light Do not store tablets or capsules in the bath room, in damp places near the kitchen sink Heat and dampness will cause the medicines to break down

Pharmacology:

Losartan, the first of a new class of hypertensives, is an angioten II receptor antagonist. Losartan inhibits the pressor effect of angiotensin II (as well as angiotensin I ) infusions

Pharmacokinetics:

Losartan undergoes substantial first-pass metabolism by cytochrome P450 enzymes. The terminal half-life is about 2 hours and about 6 to 9 hours for the metabolite.

While maximum plasma concentrations of losartan and its metabolite are approximately equal, the AUC of the metabolite is about 4 times as great as that of losartan.

A meal slows absorption of losartan and decreases its Cmax but only minor effects on losartan AUC or on the metabolite

Pregnancy:

When pregnancy is detected, discontinue losartan as soon as possible.

Lactation:

Excercise caution and decide whether to discontinue nursing or discontinue the drug.

Children-

Safety and efficacy in children have not been established.