Prolongation of pentoxifylline aliphatic side chain positively affects the reversal of P-glycoprotein-mediated multidrug resistance in L1210/VCR line cells.

We reported previously that derivatives of pentoxifylline (PTX) reverse multidrug resistance (MDR) in P-glycoprotein (P-gp) positive L1210/VCR cells. Based on the results of a recent study using 25 N-alkylated methylxanthines with carbohydrate side-chains of various lengths, we formulated the following design criteria for a methylxanthine molecule to effectively reverse P-gp mediated MDR: i) a massive substituent at the N1 position is crucial for MDR reversal potency; ii) elongation of the substituents at the N3 and N7 positions (from methyl to propyl) increases the efficacy of a xanthine to reverse MDR; iii) elongation of the substituent at the C8 position (from H to propyl) decreases the efficacy of a xanthine to reverse MDR. Based on these criteria, we synthesized and tested for potency to reverse MDR a new PTX derivative, 1-(10-undecylenyl)-3-heptyl-7-methyl xanthine (PTX-UHM), with prolonged substituents at the N1 and N3 positions.

Reversal of P-glycoprotein mediated vincristine resistance of L1210/VCR cells by analogues of pentoxifylline. A QSAR study.

In our previous papers we described the ability of methylxanthine pentoxifylline (PTX) to depress the P-glycoprotein (P-gp) mediated multidrug resistance (MDR) of the mouse leukemic cell line L1210/VCR. Other methylxanthines like caffeine and theophylline were found to be ineffective in this respect. In the present paper we have analysed the capability of 25 methylxanthines to depress MDR of L1210/VCR cells.

Carbonyl group of aliphatic side chain of pentoxifylline does not play role for P-glycoprotein antagonizing effect of pentoxifylline.

Previously we have found that pentoxifylline (PTX), but not caffeine, theophylline, or 1-methyl-3-isobutylxanthine, affects sensitivity of L1210/VCR cells, a line with multidrug resistance mediated by P-glycoprotein (P-gp) to vincristine (VCR) and doxorubicine. Comparison of chemical structure of PTX with other above xanthines has revealed only one marked difference. PTX contains extended aliphatic chain containing reactive electrophilic carbonyl group in the position N1.

Midodrine hydrochloride in the treatment of vasovagal syncope.

Therapy of vasovagal syncope is still a subject of debate. Various pharmacotherapies were proposed. However, they are often not tolerated or ineffective.

[The antitussive effect of theophylline].

Theophylline belongs to a group of medicaments used in asthma therapy. It yields an antiinflammatory effect, reduces allergic reactions, and in respiratory airways it improves the mucociliary clearance and eminently dilates smooth muscles. Therefore, the main aim of our interest is its effect on the cough reflex.