Influence of diethylcarbamazine and mefloquine on PGI2 synthesis by the rat thoracic aorta and myometrial tissues.
1. The influence of the antifilarial drug diethylcarbamazine citrate (D) and DL-erythro mefloquine hydrochloride (Mf) on PGI2 synthesis by the male rat thoracic aorta and day-20 pregnant rat myometrium was investigated in vitro using a rat platelet antiaggregatory bioassay method. 2. Pretreatment of the tissues with D (25.5-204 microM) or Mf (24-192 microM) for 30 min at 37 degrees C significantly inhibited PGI2 synthesis in a concentration-dependent manner. 3. D exhibited its inhibitory effect even in presence of exogenous arachidonic acid (AA) (16.6 microM) whereas Mf lost its inhibitory effect in presence of AA. 4. Pretreatment of urethane-anaesthetized rats with D (32 mumol kg-1) but not Mf (7.5 mumol kg-1) for 30 min significantly antagonized AA (4 nmol kg-1)-induced hypotension. 5. Furthermore, D (0.25-0.5 microM) antagonized AA-induced aggregation in rabbit platelet-rich plasma without affecting that of ADP. 6. D seemed to interfere with the action of the PG endoperoxide synthase (PG cyclooxygenase) whereas Mf seemed to interfere with the action of phospholipase A2 (PLA2) enzyme. 7. D may have exerted its effect via release of toxic O2 radicals whereas Mf effect may have been due to an interaction with PLA2 substrate phospholipids. 8. The demonstrated inherent property of these two drugs to inhibit the synthesis of the potent vasodilator, platelet antiaggregatory, anticonvulsant and antiinflammatory mediator PGI2 may partly contribute towards better understanding of the biochemical mechanisms that underly some of the previously known but poorly understood actions of these drugs.
el Tahir
K E
KE
Department of Pharmacology, College of Pharmacy, King Saud University, Riyadh, Kingdom of Saudi Arabia.
al-Kharji
A M
AM
Ageel
A M
AM
D000244:Adenosine Diphosphate / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects; D016718:Arachidonic Acid / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D004049:Diethylcarbamazine / Q000494:pharmacology*; D015232:Dinoprostone / Q000096:biosynthesis*; D011464:Epoprostenol / Q000096:biosynthesis; D005260:Female; D015767:Mefloquine / Q000494:pharmacology*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D009215:Myometrium / Q000187:drug effects / Q000378:metabolism*; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains
D016718:Arachidonic Acid; D000244:Adenosine Diphosphate; D011464:Epoprostenol; D015232:Dinoprostone; D015767:Mefloquine; D004049:Diethylcarbamazine